-
Supporting Information
Table of Contents
1. General directions S2
2. Synthesis of (±)-indolines 5b-f and 5h-q S3-S9
3. Synthesis of sulfonylating agent -
2-Isopropyl-4-nitrobenzenesulfonyl chloride S10-S11
4. Synthesis of (±)-indoline sulfonamides 6-8a, 6b-f and 6i-q
S12-S17
5. Synthesis and resolution of catalysts 4a and 4b S18-S24
6. Assignment of the absolute configuration of catalyst 4a
enantiomers S25-27
7. KR of (±)-2-methylindoline (5a) – Optimisation using catalyst
(-)-4a S28
8. KR of (±)-indolines 5a-5q – Analytical scale resolutions
S29-S44
9. KR of (±)-2-methylindoline (5a) – Scale up, deprotection and
catalyst recovery S45-S47
10. Conformational analysis on sulfonyloxypyridinium salt
intermediate 9 S48
11. References S49
12. Spectra for all new compounds S50-S124
-
S2
1. General Directions
All reactions were performed under nitrogen using oven-dried
glassware unless stated otherwise. Kinetic
resolutions were performed under an atmosphere of argon. Yields
refer to chromatographically and
spectroscopically (1H-NMR) homogenous materials, unless
otherwise indicated. MeCN, CH2Cl2, THF, Et2O,
DMF, and toluene were dried and deoxygenated with a Grubbs
Pure-Solv 400 solvent purification system. The
moisture content of the solvents was monitored by Karl Fischer
coloumetric titration (Mettler-Toledo DL39). All
other materials including: (±)-2-methylindoline (5a),
(±)-indoline-2-carboxylic acid, 3-methylbut-1-yne, (±)-2-
phenylindoline (5g), 5-chloro-2-methyl-1H-indole,
2,5-dimethyl-1H-indole, 5-methoxy-2-methyl-1H-indole, 2,3-
dimethylindole, 1,2,3,4-tetrahydrocyclopenta[b]indole,
2,3,4,9-tetrahydro-1H-carbazole and 2,3,4,9-Tetrahydro-
1H-pyrido[3,4-b]indole were obtained from commercial suppliers
and used without further purification unless
stated otherwise. Flash chromatography (FC) was performed on
silica gel (Merck Kieselgel 60 F254 230-400
mesh) unless otherwise stated. Thin Layer Chromatography was
performed on Merck aluminium-backed plates
pre-coated with silica (0.2 mm, 60 F254) which were visualized
either by quenching of ultraviolet fluorescence
(λmax= 254 and 366 nm) or by charring with 10% KMnO4 in 1 M
H2SO4. Melting points were determined on a
Stanford Research System OptiMelt. Optical rotations were
measured with a Bellingham Stanley APP440+
Polarimeter. Standard infra-red spectra were recorded on
Perkin-Elmer Two Spectrum ATR-IR spectrometer and
Shimadzu IRAffinity-1S. Only selected absorbances are reported.
1H NMR spectra were recorded at 400 MHz on
a Bruker DRX-400 instrument. Chemical shifts (H) are quoted in
parts per million (ppm), referenced to the CHCl3
residual solvent peak as an internal standard. Coupling
constants (J) are reported to the nearest 0.1 Hz. 13C NMR
spectra were recorded at 100 MHz on Bruker AMX- 400 instrument.
Chemical shifts (C) are quoted in ppm,
referenced to the CHCl3 residual solvent peak as an internal
standard. High-resolution mass spectra (m/z) were
recorded on Micromass Autospec Premier spectrometer with
magnetic sector detector. High Resolution Mass
Spectrometry (HRMS) measurements are valid to ±5ppm. GC analyses
were carried out using an Agilent 7890B
Series GC equipped with a Varian GC capillary column (WCOT fused
silica 30 m × 0.32 mm; film thickness 0.25
μm), a flame ionization detector, a split/splitless injector and
an Agilent Technologies 7683 B Series auto sampler.
Hydrogen gas was employed as the carrier gas with a flow rate of
30 mL/min using a constant flow mode. High-
purity nitrogen gas was used as a make-up gas for the detector
at a flow rate of 25 mL/min. Samples were injected
in split-less mode at an oven temperature of 100 °C. The oven
temperature was programmed as follows: 100 °C
held for 1 min, then ramped at 30 °C/min to 180 °C. Peaks were
quantified with Agilent Technologies ChemStation
software. HPLC analysis was carried out using an Agilent HP
Series 1100 HPLC. ECD spectra were run on a
Jasco J 810 spectropolarimeter using a 1 cm path length quartz
cuvette with 1 nm bandwidth at 298K. Infra Red
and vibrational circular dichroism (VCD) spectra were recorded
on a Bruker PMA 50 accessory coupled to a
Tensor 27 Fourier transform infrared spectrometer. A
photoelastic modulator (Hinds PEM 90) set at l/4 retardation
was used to modulate the handedness of the circular polarized
light. Demodulation was performed by a lock-in
amplifier (SR830 DSP). An optical low-pass filter (< 1800
cm-1) in front of the photoelastic modulator was used
to enhance the signal/noise ratio. Solutions of ca. 2.1 mg of
catalyst 4a in 160 ml CDCl3were prepared and
measured in a cell equipped with CaF2 windows and a 200 mm
spacer. The spectrum of the neat solvent served as
the reference and was subtracted from the spectra of the
enantiomers. For both the sample and reference 24,000
scans at 4 cm-1 resolution were averaged. All quantum mechanical
studies were undertaken using the Gaussian 09
software.[1]
-
S3
2. Synthesis of (±)-indolines 5b-f and 5h-q
(±)-Indolin-2-ylmethanol[2]
(±)-Indoline-2-carboxylic acid (499 mg, 3.05 mmol, 1 eq.) was
dissolved in dry THF (35 mL)
and lithium aluminium hydride (351 mg, 9.25 mmol, 3 eq.) was
added at 0 °C while stirring.
The solution was allowed to warm to rt and was stirred for 1.5
h. The reaction was quenched by adding potassium
sodium tartrate (20 mL, 10 % w/v) at 0 °C and filtered. The
filtrate was treated with sat. NH4Cl (20 mL), extracted
with EtOAc (3 20 mL) dried over MgSO4 and conc. in vacuo. The
crude residue was purified by FC (eluent:
10% MeOH/CH2Cl2) to afford alcohol as a yellow solid (432 mg,
2.9 mmol, 95%). 1H NMR (400 MHz, CDCl3,
ppm): 7.09 (dd, J = 7.3, 1.3 Hz, 1H), 7.03 (d, J = 7.1 Hz, 1H),
6.73 (td, J = 7.4, 1.0 Hz, 1H), 6.65 (d, J = 7.8 Hz,
1H), 4.11 - 4.00 (m, 1H), 3.73 (dd, J = 10.8, 3.9 Hz, 1H), 3.58
(dd, J = 10.9, 6.4 Hz, 1H), 3.12 (dd, J = 15.8, 9.3
Hz, 1H), 2.84 (dd, J = 15.8, 7.9 Hz, 1H), 2.78 (s, 2H).
Spectroscopic data in agreement with literature.[2]
(±)-2-(((Triethylsilyl)oxy)methyl)indoline (5b)
To a well-stirred solution of (±)-indolin-2-ylmethanol (250 mg,
1.68 mmol, 1 eq.), NMI
(15 L, 0.168 mmol, 10 mol%) and DIPEA (0.58 mL, 3.36 mmol, 2
eq.) in CH2Cl2 (17
mL) was added TES-Cl (0.34 mL, 0.201 mmol, 1.2 eq.). The
colourless solution was stirred at rt for 21.5 h and
then conc. in vacuo. The crude residue was purified by FC
(eluent: 10% EtOAc/hexanes) to yield silylated indoline
product as a colourless liquid (193 mg, 0.74 mmol, 44%). IR
(film, cm-1): 3354, 2953, 2911, 2876, 1611, 1485,
1466, 1377, 1342, 1319, 1244, 1016, 974, 912, 800. 1H NMR (400
MHz, CDCl3, ppm): 7.08 (dd, J = 7.2, 1.3
Hz, 1H), 7.02 (td, J = 7.6, 1.3 Hz, 1H), 6.69 (td, J = 7.4, 1.1
Hz, 1H), 6.63 (d, J = 7.8 Hz, 1H), 4.27 (s, 1H), 3.96
(m, 1H), 3.57 (m, 2H), 3.12 (dd, J = 15.8, 9.1 Hz, 1H), 2.65
(dd, J = 15.8, 5.8 Hz, 1H), 0.98 (td, J = 8.0, 1.8 Hz,
9H), 0.63 (qd, J = 8.0, 1.7 Hz, 6H). 13C NMR (101 MHz, CDCl3):
150.7, 128.3, 127.5, 124.9, 118.6, 109.6,
66.4, 60.6, 32.3, 6.9, 4.5. HRMS (ES+): Found: 264.1796 ([M+H]
C15H25NOSi Requires: 264.1784).
(±)-2-(((Triisopropylsilyl)oxy)methyl)indoline (5c)
To a well-stirred solution of (±)-indolin-2-ylmethanol (250 mg,
1.68 mmol, 1 eq.), NMI
(15 L, 0.168 mmol, 10 mol%) and DIPEA (0.58 mL, 3.36 mmol, 2
eq.) in CH2Cl2 (17
mL) was added TIPSCl (0.43 mL, 0.201 mmol, 1.2 eq.). The yellow
solution was stirred
at rt for 22.5 h and then conc. in vacuo. The crude residue was
purified by FC (eluent: 5% Et2O/hexanes) to afford
silylated indoline product as a colourless oil (250 mg, 0.82
mmol, 49%). IR (film, cm-1): 3387, 2941, 2893, 2864,
1611, 1485, 1466, 1246, 1105, 883, 791, 746, 683. 1H NMR (400
MHz, CDCl3, ppm): 7.06 (d, J = 7.3 Hz, 1H),
7.01 (t, J = 7.5 Hz, 1H), 6.68 (t, J = 7.4 Hz, 1H), 6.62 (d, J =
7.7 Hz, 1H), 4.28 (s, 1H), 4.02 - 3.91 (m, 1H), 3.70
- 3.55 (m, 2H), 3.11 (dd, J = 15.8, 9.0 Hz, 1H), 2.64 (dd, J =
15.8, 5.5 Hz, 1H), 1.12 - 1.00 (m, 21H). 13C NMR
(101 MHz, CDCl3, ppm): 150.7, 128.3, 127.5, 125.0, 118.5, 109.6,
67.0, 60.7, 32.2, 18.1, 12.1. HRMS (ES+):
Found: 306.2253 ([M+H] C18H32NOSi Requires: 306.2253).
(±)-2-(((tert-Butyldimethylsilyl)oxy)methyl)indoline (5d)[3]
To a well-stirred solution of (±)-indolin-2-ylmethanol (250 mg,
1.68 mmol, 1 eq.),
NMI (15 L, 0.168 mmol, 10 mol%) and DIPEA (0.58 mL, 3.36 mmol, 2
eq.) in
CH2Cl2 (17 mL) was added TBSCl (300 mg, 0.201 mmol, 1.2 eq.).
The colourless
solution was stirred at rt for 21.5 h and then conc. in vacuo.
The crude residue was purified by FC (eluent: 5%
Et2O/hexanes) to yield indoline product as a colourless liquid
(393 mg, 1.50 mmol, 89%). 1H NMR (400 MHz,
-
S4
CDCl3, ppm): 7.07 (dd, J = 7.3, 1.2 Hz, 1H), 7.01 (t, J = 7.6,
1.0 Hz, 1H), 6.68 (t, J = 7.4, 1.0 Hz, 1H), 6.62 (d,
J = 7.8 Hz, 1H), 4.21 (s, 1H), 3.99 - 3.88 (m, 1H), 3.63 - 3.50
(m, 2H), 3.10 (dd, J = 15.8, 9.0 Hz, 1H), 2.64 (dd,
J = 15.8, 5.8 Hz, 1H), 0.91 (s, 9H), 0.06 (d, J = 0.9 Hz, 6H).
HRMS (ES+): Found: 264.1789 ([M+H] C15H26NOSi
Requires: 264.1784). Spectroscopic data in agreement with
literature.[3]
General Procedure A - Reduction of indoles
To a flask containing tin-powder (4.5 eq.), HCl (aq. 37% v/v,
3.2 mL/mmol indoline) and EtOH (9.7 mL/mmol
indoline) was added indoline (1 eq.) and the mixture stirred at
70 °C for several hours. Then, KOH (aq., 20% v/w,
23.5 mL/mmol indole) was added and the mixture extracted with
Et2O (3 × 35 mL/mmol), filtered through Celite,
dried over MgSO4 and conc. in vacuo. The residue was purified by
FC to afford desired indoline product.
2-(2-Methylbutyne)-aniline[4]
3-Methylbut-1-yne (1.79 mL, 17.5 mmol, 1.75 eq.) was added to a
well-stirred solution of 2-
iodovanilin (2.19 g, 10 mmol, 1 eq.), CuI (8.6 mg, 0.045 mmol,
0.5 mol%.), Pd(PPh3)2Cl2 (37
mg, 0.0525 mmol, 0.5 mol%) in freshly distilled Et3N (63 mL).
The solution was left to stir
under N2 for 72 h. Then, the solution was conc. in vacuo and the
residue dissolved in Et2O (150 mL). The solution
was filtered through Celite, dried and conc. in vacuo. The crude
residue was purified by FC (eluent: 30% - 40%
CH2Cl2/hexanes) to yield product as a yellow oil (1.16, 7.3
mmol, 73%). 1H NMR (400 MHz, CDCl3, ppm):
7.32 - 7.19 (m, 1H), 7.10 (ddd, J = 8.8, 7.4, 1.5 Hz, 1H),
6.74-6.62 (m, 2H), 4.16 (s, 2H), 2.86 (hept, J = 6.9 Hz,
1H), 1.31 (d, J = 6.9 Hz, 6H). HRMS (CI+): Found: 160.1118
([M+H] C11H14N Requires: 160.1121).
Spectroscopic data in agreement with literature.[4]
2-Isopropylindole[5]
2-(2-Methylbutyne)-aniline (1.06 g, 6.7 mmol, 1 eq.) was added
to a well-stirred solution of
CuI (4.2 mg, 0.022 mmol, 0.003 eq.) in DMF (30 mL). The yellow
solution darkened as it was
heated to reflux for 4 h followed cooling to rt and stirring for
a further 16 h. Then it was diluted with Et2O (150
mL), washed with dilute brine (40 mL), dried over MgSO4 and
conc. in vacuo. The crude residue was purified by
FC (eluent: 40% CH2Cl2/hexanes) to yield desired indole product
as a yellow solid (616 mg, 3.9 mmol, 58%). 1H
NMR (400 MHz, CDCl3, ppm): 7.92 (s, 1H), 7.57 (d, J = 7.8 Hz,
1H), 7.34 (d, J = 8.4 Hz, 1H), 7.21 - 7.02 (m,
2H), 6.30 (s, 1H), 3.11 (hept, J = 6.8 Hz, 1H), 1.39 (d, J = 6.8
Hz, 6H). HRMS (ES+): Found: 160.1131 ([M+H]
C11H14N Requires: 160.1126). Spectroscopic data in agreement
with literature.[5]
(±)-2-Isopropylindoline (5e)[4]
Following the General Procedure A, 2-isopropylindole (271 mg,
1.7 mmol) and Sn (914 mg,
7.7 mmol) were reacted for 14.5 h during which the solution went
from a grey suspension to a
clear solution. After work-up, the crude residue was purified by
FC (eluent: 40% CH2Cl2/hexanes) to yield indoline
product as an oily yellow solid (161 mg, 1.0 mmol, 59%). 1H NMR
(400 MHz, CDCl3, ppm): 7.07 (d, J = 8.5
Hz, 1H), 7.00 (td, J = 7.7, 1.0 Hz, 1H), 6.67 (td, J = 7.5, 1.0
Hz, 1H), 6.60 (d, J = 7.7 Hz, 1H), 3.92 (s, 1H), 3.57
(ddd, J = 9.8, 8.7, 7.5 Hz, 1H), 3.07 (dd, J = 15.6, 8.7 Hz,
1H), 2.74 (dd, J = 15.5, 9.9 Hz, 1H), 1.87 - 1.71 (dh, J
-
S5
= 13.6, 6.8 Hz , 1H), 1.00 (d, J = 6.8 Hz, 3H), 0.95 (d, J = 6.8
Hz, 3H). Spectroscopic data in agreement with
literature.[4]
2-n-Butyl-1H-indole[6]
An oven-dried Schlenk-flask was charged with indole (117 mg, 1
mmol, 1 eq.), BuBr (0.24
mL, 2.23 mmol, 2.23 eq.), PdCl2(MeCN)2 (26 mg, 0.1 mmol, 10
mol%), K2CO3 (276 mg, 2
mmol, 2 eq.) and DMA (5 mL). The flask was purged with argon and
degassed through 3 freeze-pump-thaw cycles.
The reaction reaction was then heated to 70 °C under argon for
20.5 h. The mixture was conc. in vacuo and the
crude residue was purified by FC (eluent: 5% Et2O/hexanes) to
afford product as a yellow oil (93 mg, 0.54 mmol,
54%). 1H NMR (400 MHz, CDCl3): 7.78 (s, 1H), 7.62 - 7.54 (m,
1H), 7.35 - 7.27 (m, 1H), 7.21 - 7.09 (m, 2H),
6.33 - 6.25 (m, 1H), 2.77 (t, J = 7.7 Hz, 2H), 1.79 - 1.67 (m,
2H), 1.47 (h, J = 7.4 Hz, 2H), 1.01 (t, J = 7.3 Hz, 3H).
HRMS (ES+): Found: 174.1277 ([M+H] C12H16N Requires: 174.1283).
Spectroscopic data in agreement with
literature.[6]
(±)-2-n-Butylindoline (5f)[7]
Following General Procedure A, 2-n-butylindole (54 mg, 0.31
mmol) and Sn (167 mg) were
reacted for 5.5 h at 90 °C during which the solution went from a
grey suspension to a clear
solution. After work-up, the crude residue was purified by FC
(eluent: 40% CH2Cl2/hexanes) to afford indoline
product as a yellow oil (42 mg, 0.24 mmol, 77%). 1H NMR (400
MHz, CDCl3, ppm): 7.07 (dd, J = 7.2, 1.4 Hz,
1H), 7.00 (td, J = 7.6, 1.1 Hz, 1H), 6.68 (td, J = 7.5, 1.0 Hz,
1H), 6.60 (d, J = 7.7 Hz, 1H), 4.09 - 3.44 (m, 2H),
3.12 (dd, J = 15.5, 8.6 Hz, 1H), 2.68 (dd, J = 15.5, 8.5 Hz,
1H), 1.60 (ttd, J = 9.0, 6.8, 6.2, 3.9 Hz, 2H), 1.46 - 1.26
(m, 4H), 0.99 - 0.84 (m, 3H). Spectroscopic data in agreement
with literature.[7]
(±)-Methyl indoline-2-carboxylate (5h)[8]
Acetyl chloride (3.0 mL, 42 mmol, 14 eq.) and MeOH (30 mL) were
stirred for 5 min before
adding (±)-indoline-2-carboxylic acid (490 mg, 3 mmol, 1 eq.).
The mixture was refluxed
for 24 h after which the solvent had evaporated. The residue was
purified by FC (eluent: 80% - 100%
CH2Cl2/hexanes) to afford esterified product as a yellow oil
(508 mg, 2.9 mmol, 97%). 1H NMR (400 MHz,
CDCl3): 7.12 - 7.00 (m, 2H), 6.79 - 6.68 (m, 2H), 4.39 (dd, J =
10.2, 5.5 Hz, 1H), 3.40 (dd, J = 16.1, 10.1 Hz,
1H), 3.32 (dd, J = 16.1, 5.5 Hz, 1H). Spectroscopic data in
agreement with literature.[8]
(±)-5-Chloro-2-methylindoline (5i)[9]
Following General Procedure A, 5-chloro-2-methyl-1H-indole (250
mg, 1.5 mmol) and
Sn (797 mg, 6.7 mmol) were reacted for 5 h at 90 °C during which
the solution went from
a grey suspension to a clear solution. After work-up, the crude
residue was purified by FC
(eluent: 50% CH2Cl2/hexanes) to yield indoline product as a
colourless oil (189 mg, 1.13 mmol, 75%). 1H NMR
(400 MHz, CDCl3, ppm): 7.02 (dt, J = 2.2, 1.2 Hz, 1H), 6.95
(ddt, J = 8.2, 1.9, 1.0 Hz, 1H), 6.49 (d, J = 8.2 Hz,
1H), 4.00 (ddq, J = 8.6, 7.7, 6.2 Hz, 1H), 3.75 (s, 1H), 3.12
(dd, J = 15.7, 8.5 Hz, 1H), 2.61 (ddt, J = 15.7, 7.5, 1.0
Hz, 1H), 1.28 (d, J = 6.2 Hz, 3H). Spectroscopic data in
agreement with literature.[9]
(±)-2,5-Dimethylindoline (5j)[10]
Following General Procedure A, 2,5-dimethyl-1H-indole (250 mg,
1.7 mmol) and Sn (914
mg, 7.7 mmol) were reacted for 4 h at 90 °C during which the
solution went from a grey
-
S6
suspension to a clear solution. After work-up, the crude residue
was purified by FC (eluent: 100% CH2Cl2) to yield
indoline product as a white solid (164 mg, 1.12 mmol, 66%). 1H
NMR (400 MHz, CDCl3, ppm): 6.91 (s, 1H),
6.82 (d, J = 7.7 Hz, 1H), 6.53 (d, J = 7.8 Hz, 1H), 3.97 (tq, J
= 8.2, 6.3 Hz, 1H), 3.61 (s, 1H), 3.11 (dd, J = 15.4,
8.4 Hz, 1H), 2.61 (dd, J = 15.4, 7.8 Hz, 1H), 2.25 (s, 3H), 1.29
(d, J = 6.3 Hz, 3H). Spectroscopic data in agreement
with literature.[10]
(±)-5-Methoxy-2-methylindoline (5k)[11]
Following General Procedure A, 5-methoxy-2-methyl-1H-indole (30
mg, 0.2 mmol) and
Sn (109 mg, 0.92 mmol) were reacted for 3 h at 90 °C during
which the solution went
from a grey suspension to a clear solution. After work-up, the
crude residue was purified
by FC (eluent: 10% MeOH/CH2Cl2) to afford indoline product as a
orange solid (27 mg, 0.16 mmol, 83%).1H
NMR (400 MHz, CDCl3, ppm): 6.72 (dd, J = 2.4, 1.2 Hz, 1H), 6.59
(ddt, J = 8.5, 2.6, 0.9 Hz, 1H), 6.54 (d, J =
8.4 Hz, 1H), 3.97 (tq, J = 8.1, 6.2 Hz, 1H), 3.74 (s, 3H), 3.38
(s, 1H), 3.11 (m, 1H), 2.62 (ddt, J = 15.5, 7.9, 1.0
Hz, 1H), 1.29 (d, J = 6.2 Hz, 3H). Spectroscopic data in
agreement with literature.[11]
(±)-2-Methyl-6-nitroindoline[12]
(±)-2-Methylindoline (1.0 g, 3.8 mmol, 1 eq.) was added dropwise
to conc. H2SO4 (8 mL)
at 5°C. Then the temperature was lowered to 0°C and conc. HNO3
(0.37 mL) was added
dropwise after which the solution turned purple. After 100 min,
the solution was quenched
with NaOH (10% w/w, 100 mL) and extracted with CH2Cl2 (3 70 mL).
The combined organic phase was dried
over MgSO4 and concentrated in vacuo. The crude product was
purified by FC (eluent: 10% Et2O/hexanes) to
afford nitrated indoline product as a red solid (582 mg, 3.3
mmol, 43%). 1H NMR (400 MHz, CDCl3, ppm):
7.56 (dd, J = 8.0, 2.1 Hz, 1H), 7.32 (d, J = 2.1 Hz, 1H), 7.12
(dt, J = 8.1, 1.1 Hz, 1H), 4.12 (ddq, J = 8.7, 7.4, 6.2
Hz, 1H), 4.72 (s, 1H), 3.21 (ddd, J = 16.6, 8.8, 1.1 Hz, 1H),
2.69 (ddd, J = 16.6, 7.4, 1.2 Hz, 1H), 1.31 (d, J = 6.2
Hz, 3H). HRMS (ES+): Found: 179.0819 ([M+H] C9H11N2O2 Requires:
179.0821). Spectroscopic data in
agreement with literature.[12]
(±)-2-Methylindolin-6-amine
(±)-2-Methyl-6-nitroindoline (570 mg, 3.2 mmol, 1 eq.) in
EtOAc/EtOH (1:1, 26 mL) was
added to Pd/C (10% w/w, 175 mg) and the flask was evacuated and
filled with H2 (× 3)
and the resulting black suspension was stirred at rt for 5.5 h
under H2 (1 atm.). Then, the
mixture was added to EtOAc (100 mL) and the phases were
separated. The organic phase was filtered over Celite,
dried over MgSO4 and conc. in vacuo. The crude residue was
purified by FC (Eluent: 2.5 % MeOH/hexanes) to
yield aniline productas a dark red oil (416 mg, 2.8 mmol, 88%).
IR (film, cm-1): 3334, 3213, 2959, 1621, 1504,
1464, 1377, 1270, 1178, 963, 838, 804, 622. 1H NMR (400 MHz,
CDCl3, ppm): 6.84 (dd, J = 7.6, 1.2 Hz, 1H),
6.10 - 6.02 (m, 1H), 6.01 (d, J = 2.0 Hz, 1H), 4.03 - 3.88 (m,
1H), 3.51 (s, 3H), 3.04 (dd, J = 14.9, 8.4 Hz, 1H),
2.53 (dd, J = 14.9, 7.6 Hz, 1H), 1.27 (d, J = 6.2 Hz, 3H). 13C
NMR (101 MHz, CDCl3, ppm): 152.09, 146.15,
125.06, 120.13, 105.43, 97.16, 55.64, 37.03, 22.34. HRMS (ES+):
Found: 149.1073 ([M+H] C9H13N2 Requires:
149.1079).
-
S7
(±)-tert-Butyl 6-amino-2-methylindoline-1-carboxylate
(±)-2-Methylindolin-6-amine (100 mg, 0.67 mmol, 1 eq.) and Boc2O
(0.16 mL, 0.67 mmol,
1 eq.) were dissolved in CH2Cl2 (1 mL) and stirred for 20 h at
rt. The solution was then
diluted with CH2Cl2 (5 mL), washed with NaHCO3 (2 mL), brine (2
mL), dried over MgSO4
and conc. in vacuo. The resulting crude mixture was purified by
FC (eluent: 0.9% MeOH/CH2Cl2) to afford N-
Boc protected indoline as a brown oil (41 mg, 0.16 mmol, 24%).
IR (film, cm-1): 3365, 2973, 2929, 2863, 1691
(C=O), 1616, 1530, 1501, 1460, 1394, 1291, 1164, 1042. 1H NMR
(400 MHz, CDCl3, ppm): 7.24 (s, 1H), 6.89
(dt, J = 7.7, 1.1 Hz, 1H), 6.28 (dd, J = 7.8, 2.2 Hz, 1H), 4.45
(s, 1H), 3.57 (s, 2H), 3.22 (ddd, J = 15.2, 9.5, 1.3 Hz,
1H), 2.48 (dd, J = 15.2, 2.3 Hz, 1H), 1.55 (s, 9H), 1.26 (d, J =
6.3 Hz, 3H). 13C NMR (101 MHz, CDCl3, ppm):
152.4, 146.2, 142.8, 125.4, 120.0, 109.1, 103.1, 80.5, 56.1,
35.2, 28.6, 21.3. HRMS (ES+): Found: 249.1601
([M+H] C14H21N2O2 Requires: 249.1598).
(±)-tert-Butyl
6-(dimethylamino)-2-methylindoline-1-carboxylate
To a well-stirred solution of (±)-tert-butyl
6-amino-2-methylindoline-1-carboxylate (25
mg, 0.1 mmol, 1 eq.), TBAI (2.5 mg, 0.007 mmol, 7 mol%) and KOH
(14 mg, 0.25 mmol,
2.5 eq.) in benzene:H2O (7:1, 0.8 mL) was added MeI (15 L, 0.25
mmol, 2.5 eq.) dropwise
at rt. The solution was heated at 90°C for 25 h after which the
mixture was cooled to rt and extracted with Et2O (3
2 mL). The combined organic phase was washed with brine (2 mL),
dried over MgSO4 and conc. in vacuo. The
resulting crude oil was purified by FC (eluent: 0.5%
MeOH/CH2Cl2) to afford product as a yellow oil (15 mg,
0.052 mmol, 52%). IR (film, cm-1): 2974, 2932, 2863, 1695, 1617,
1509, 1617, 1509, 1454, 1388, 1288, 1167,
1043, 952, 868, 844, 762. 1H NMR (400 MHz, CDCl3, ppm): 7.53 -
7.20 (m, 1H), 6.98 (dt, J = 8.2, 1.0 Hz, 1H),
6.36 (dd, J = 8.2, 2.4 Hz, 1H), 4.49 (s, 1H), 3.29 - 3.18 (m,
1H), 2.93 (s, 6H), 2.49 (dd, J = 15.3, 2.4 Hz, 1H), 1.47
(s, 9H), 1.32 - 1.22 (m, 3H). 13C NMR (101 MHz, CDCl3, ppm):
152.3, 150.8, 143.0, 125.0, 107.2, 101.1, 100.4,
80.4, 56.0, 41.2, 34.8, 28.5, 21.1. HRMS (ES+): Found: 277.1922
([M+H] C16H25N2O2 Requires: 277.1916).
(±)-N,N-2-Trimethylindolin-6-amine (5l)
To a well-stirred solution of (±)-tert-butyl
6-(dimethylamino)-2-methylindoline-1-
carboxylate (40.3 mg, 0.15 mmol, 1 eq.) in CH2Cl2 (2 mL),
trifluoroacetic acid (0.8 mL)
was added dropwise at rt. The dark solution was stirred for 3 h
and was then conc. in vacuo.
The residue was taken up in CH2Cl2 washed with sat. NaHCO3 (5
mL), dried of MgSO4 and conc. in vacuo. The
crude residue was purified by FC (eluent: 1% MeOH/0.1%
Et3N/CH2Cl2) to afford deprotected indoline product
as a colourless oil (26 mg, 0.15 mmol, 99%). IR (film, cm-1):
3360, 2957, 2841, 1620, 1582, 1510, 1448, 1354,
1239, 1099, 974, 815. 1H NMR (400 MHz, CDCl3, ppm): 6.94 (d, J =
8.0 Hz, 1H), 6.17 - 6.09 (m, 2H), 4.02 -
3.91 (m, 1H), 3.60 (s, 1H), 3.06 (dd, J = 14.9, 8.3 Hz, 1H),
2.88 (s, 6H), 2.55 (ddd, J = 14.9, 7.5, 1.1 Hz, 1H), 1.27
(dd, J = 6.2, 2.4 Hz, 3H). 13C NMR (101 MHz, CDCl3, ppm): 152.0,
151.2, 124.8, 117.8, 103.7, 95.3, 55.6, 41.3,
37.0, 22.4. HRMS (ES+): Found: 177.1383 ([M+H] C11H17N2
Requires: 177.1392).
(±)-cis and (±)-trans-2,3-Dimethylindolines (5m and 5n)
Sodium cyanoborohydride (3.0 g, 3 eq.) was dissolved in glacial
acetic acid (20
mL) and the resulting solution carefully transferred by canula
to a solution of
2,3-dimethylindole (2.28 g, 15.7 mmol) in glacial acetic acid
(130 mL). The
resulting solution was stirred in an open flask for 12 h at room
temperature. Sat. K2CO3 (aq.) was added until the
-
S8
reaction mixture had become basic. Extraction with Et2O (3 × 100
mL) followed by drying of the combined organic
phases over MgSO4 and rotary evaporation afforded crude product
which was purified by FC (eluent: 3%
EtOAc/hexanes) to afford:
(±)-cis-2,3-dimethylindoline (5m)[3] (211 mg, 1.43 mmol, 9%). 1H
NMR (400 MHz, CDCl3, ppm): δ 7.11-7.03
(m, 2H), 6.78-6,74 (m, 1H), 6.64 (d, J = 7.7 Hz, 1H), 4.01-3.94
(m, 1H), 3.57 (br s, 1H), 3.33-3.26 (m, 1H), 1.21
(d, J = 7.2 Hz, 3H), 1.17 (d, J = 6.5 Hz, 3H). LRMS (m/z +ES):
Found: 148.6 (M+H C10H14N Requires: 148.1).
Spectroscopic data in agreement with literature.[3]
(±)-trans-2,3-dimethylindoline (5n)[3] (502 mg, 3.41 mmol, 22%).
1H NMR (400 MHz, CDCl3, ppm): δ 7.08-
7.01 (m, 2H), 6.78-6.74 (m, 1H), 6.65-6.63 (m, 1H), 3.88 (br s,
1H), 3.53-3.46 (m 1H), 2.89-2.81 (m, 1H), 1.36-
1.33 (m, 6H). LRMS (m/z +ES): Found: 148.3 (M+H C10H14N
Requires: 148.1). Spectroscopic data in agreement
with literature.[3]
(±)-cis-1,2,3,3a,4,8b-Hexahydrocyclopenta[b]indole (5o)[13]
Following General Procedure A,
1,2,3,4-tetrahydrocyclopenta[b]indole (236 mg, 1.5 mmol) and
Sn (797 mg, 6.7 mmol) were reacted for 4 h during which the
solution went from a red suspension
to a clear yellow solution. After work-up, the crude residue was
purified by FC (eluent: 25 - 50%
CH2Cl2/hexanes) to yield indoline product as a yellow oil (81
mg, 0.51 mmol, 34%). 1H NMR (400 MHz, CDCl3,
ppm): 7.10 - 6.95 (m, 2H), 6.68 (t, J = 7.3 Hz, 1H), 6.53 (d, J
= 7.8 Hz, 1H), 4.37 (ddd, J = 8.6, 6.0, 2.3 Hz, 1H),
4.12 - 3.15 (m, 2H), 1.96 (dddd, J = 12.5, 10.6, 8.8, 6.5 Hz,
1H), 1.85 - 1.49 (m, 5H). Spectroscopic data in
agreement with literature.[13]
(±)-cis-2,3,4,4a,9,9a-Hexahydro-1H-carbazole (5p)[3]
Following General Procedure A, 2,3,4,9-tetrahydro-1H-carbazole
(499 mg, 2.91 mmol) and Sn
(1.59 g, 13.4 mmol) were reacted for 4 h during which the
solution went from a red suspension to
a clear yellow solution. After work up, the crude residue was
purified by FC (eluent: 5%
EtOAc/hexanes) to afford product as a beige solid (375 mg, 2.18
mmol, 75%). 1H NMR (400 MHz, CDCl3, ppm):
7.09 (d, J = 7.4 Hz, 1H), 7.03 (t, J = 7.4 Hz, 1H), 6.75 (td, J
= 7.4, 1.0 Hz, 1H), 6.68 (d, J = 7.4 Hz, 1H), 3.73
(td, J = 6.7, 5.1 Hz, 1H), 3.10 (q, J = 6.7 Hz, 1H), 1.82 – 1.72
(m, 2H), 1.72 – 1.62 (m, 1H), 1.61 – 1.49 (m, 2H),
1.48 – 1.25 (m, 3H). HRMS (m/z +ES): Found: 174.1282 (M+H
C12H16N Requires: 174.1283). Spectrscopic data
in agreement with literature.[3]
tert-Butyl
3,4-dihydro-1H-pyrido[3,4-b]indole-2(9H)-carboxylate[14]
2,3,4,9-Tetrahydro-1H-pyrido[3,4-b]indole (0.50 g, 2.9 mmol, 1
eq.), Boc2O (0.75 mL, 3.25
mmol, 1.13 eq.) and K2CO3 (454 mg, 3.25 mmol, 1.13 eq.) was
suspended in i-PrOH (5 mL)
and H2O (6 mL) and stirred at rt for 21 h. The mixture was
diluted with EtOAc (50 mL), washed
with brine (20 mL), dried of MgSO4 and conc. in vacuo. The crude
mixture was purified by FC (eluent: 25%
EtOAc/hexanes) to afford protected carboline product as a white
oily solid (610 mg, 2.24 mmol, 77%). 1H NMR
(400 MHz, CDCl3, ppm): 8.10 – 7.80 (m, 1H), 7.48 (d, J = 7.7 Hz,
1H), 7.32 (d, J = 8.0 Hz, 1H), 7.22 - 7.01 (m,
2H), 4.65 (s, 2H), 3.77 (s, 2H), 2.80 (t, J = 5.6 Hz, 2H), 1.51
(s). HRMS (CI+): Found: 273.1589 ([M+H]
C16H21N2O2 Requires: 273.1598). Spectroscopic data in agreement
with literature.[14]
-
S9
(±)-cis-tert-Butyl
4,4a,9,9a-tetrahydro-1H-pyrido[3,4-b]indole-2(3H)-carboxylate
(5q)
To a well stirred solution of tert-butyl
3,4-dihydro-1H-pyrido[3,4-b]indole-2(9H)-carboxylate
(25 mg, 0.092 mmol, 1 eq.) in glacial AcOH (1.5 mL) was added
NaBH3CN (23 mg, 0.37 mmol,
3 eq.). The solution was stirred at rt for 16 h. Then NaOH (10%
w/v, 8 mL) was added and the
solution was extracted with CH2Cl2 (3 × 5 mL), dried over MgSO4
and conc. in vacuo. The crude residue was
purified by FC (eluent: 25% - 50% CH2Cl2/hexanes) to afford
product as a colourless oil (17 mg, 0.063 mmol,
68%). IR (film, cm-1): 3332, 2975, 2928, 1686 (C=O), 1610, 1478,
1415, 1365, 1246, 1168, 1019, 868, 743. 1H
NMR (400 MHz, DMSO-d6, ppm): 6.99 (d, J = 7.2 Hz, 1H), 6.89 (td,
J = 7.6, 1.3 Hz, 1H), 6.53 (t, J = 7.3 Hz,
1H), 6.46 (d, J = 7.7 Hz, 1H), 5.59 (s, 1H), 3.74 (s, 1H), 3.41
(dd, J = 13.6, 4.2 Hz, 1H), 3.27 - 3.08 (m, 3H), 2.49
(p, J = 1.7 Hz, 1H), 1.97 - 1.79 (m, 1H), 1.67 (m , 1H), 1.37
(s, 9H). 13C NMR (101 MHz, DMSO-d6, ppm):
154.5, 151.4, 131.1, 127.3, 123.4, 117.1, 108.5, 78.4, 56.8,
44.4, 40.3, 38.5, 28.11, 25.9. HRMS (ES+): Found:
275.1764 ([M+H] C16H23N2O2 Requires: 275.1760).
-
S10
3. Synthesis of sulfonylating agent -
2-Isopropyl-4-nitrobenzenesulfonyl chloride
2-Isopropyl-4-nitrophenol[15]
2-isoPropylphenol (6.1 mL, 45 mmol, 1 eq.) was dissolved in
EtOAc (200 mL) and the solution
was cooled to 0 °C before conc. HNO3 (68% w/v, 2.95 mL, 45 mmol)
was added. The cold
solution was then transferred to an ultrasonication bath and
sonication was started. ZnCl2 (6.1 g, 45 mmol) was
added and the dark red solution was sonicated for 1 h. Then the
solution was washed with H2O (2 100 mL), brine
(100 mL) and dried over MgSO4. The solution was conc. in vacuo
to yield a dark red oil that was purified by FC
(eluent: 20% EtOAc/hexanes) to afford nitrated product as a red,
oily solid (3.1 g, 17.1 mmol, 38%). 1H NMR
(400 MHz, CDCl3, ppm): 8.13 (d, J = 2.7 Hz, 1H), 8.01 (dd, J =
8.8, 2.7 Hz, 1H), 6.81 (d, J = 8.8 Hz, 1H), 5.47
(s, 1H), 3.29 (hept, J = 6.9 Hz, 1H), 1.34 - 1.25 (m, 6H). HRMS
(ES+): Found: 182.0811 ([M+H] C9H12O3N
Requires: 182.0812). Spectroscopic data in agreement with
literature.[15]
O-(2-Isopropyl-4-nitrophenyl) dimethylcarbamothioate
To a well stirred solution of 2-isopropyl-4-nitrophenol (3.0 g,
16.6 mmol, 1 eq.) in dry DMF
(100 mL) was added DABCO (3.71 g, 33.1 mmol, 2 eq.) and
dimethylthiocarbomyl chloride
(3.07 g, 24.8 mmol, 1.5 eq.) at rt. The solution was heated to
50 °C left to stir for 5 days. The
reaction mixture was cooled down to room temperature and diluted
with water (50 mL). The solution was extracted
with CH2Cl2 (3 75 mL) and the combined organic phase was washed
with HCl (5% w/v, 50 mL), NaOH (1 M,
50 mL) and brine (50 mL). The organic phase was dried over MgSO4
and the solvent was removed in vacuo. The
crude was purified by FC (eluent: 40% CH2Cl2/hexanes) to afford
product as a yellow crystalline solid (2.72 g,
10.1 mmol, 62%). M.p 90-92 °C. IR (film, cm-1): 2965, 2871,
1523, 1481, 1395, 1346, 1287, 1226, 1184, 1121,
1073, 904, 733. 1H NMR (400 MHz, CDCl3, ppm): 8.22 (d, J = 2.7
Hz, 1H), 8.08 (dd, J = 8.8, 2.8 Hz, 1H), 7.15
(d, J = 8.8 Hz, 1H), 3.47 (s, 3H), 3.39 (s, 3H), 3.09 (hept, J =
7.0 Hz, 1H), 1.27 (d, J = 6.9 Hz, 6H). 13C NMR (101
MHz, CDCl3, ppm): 186.5, 156.0, 146.0, 142.9, 124.8, 122.6,
122.0, 43.6, 39.0, 27.7, 22.9. HRMS (CI+): Found:
269.0949 ([M+H] C12H17N3O232S2 Requires: 269.0954).
(S)-(2-Isopropyl-4-nitrophenyl) dimethylcarbamothioate
O-(2-isopropyl-4-nitrophenyl) dimethylcarbamothioate (834 mg,
3.1 mmol, 1 eq.) was
dissolved in DMA (10 mL) and heated to 180 °C in a microwave for
100 min. The solution
was conc. over a stream of N2 and the resulting residue was
purified by FC (eluent: 10 %
EtOAc/hexanes) to afford product as an off-white solid (712 mg,
2.7 mmol, 85%). M.p 132-133 °C. IR (film, cm-
1): 3078, 2965, 2870, 1661, 1516, 1341, 1261, 1101, 1043, 905,
783, 748, 692, 656. 1H NMR (400 MHz, CDCl3,
ppm): 8.20 (d, J = 2.6 Hz, 1H), 8.02 (dd, J = 8.5, 2.5 Hz, 1H),
7.67 (d, J = 8.5 Hz, 1H), 3.53 (hept, J = 6.9 Hz,
1H), 3.15 (s, 3H), 3.04 (s, 3H), 1.27 (d, J = 6.9 Hz, 6H). 13C
NMR (101 MHz, CDCl3, ppm): 165.0, 154.3, 149.0,
138.4, 135.7, 121.0, 120.8, 37.3, 31.6, 23.5. HRMS (ES+): Found:
269.0972 ([M+H] C12H17N2O332S Requires:
269.0960).
2-Isopropyl-4-nitrobenzenesulfonyl chloride
A solution of NCS (3.65 g, 27.3 mmol, 4 eq.) in MeCN (55 mL) was
added dropwise to a well-
stirred suspension of S-(2-isopropyl-4-nitrophenyl)
dimethylcarbamothioate (1.8 g, 6.8 mmol,
1 eq.) in MeCN (45 mL) and HCl (2 M, 9 mL) at 0 °C. The solution
was stirred at 0 °C for 6 h
-
S11
before being diluted with iPr2O (45 mL), washed with H2O (45 mL)
and brine (45 mL), dried over MgSO4 and
conc. in vacuo. The crude residue was purified by FC (eluent:
30% CH2Cl2/hexanes) to afford sulfonyl chloride 5
as a white solid (1.35 g, 5.1 mmol, 75% yield). M.p = 110-111
°C. IR (film, cm-1): 3100, 2972, 1541, 1531, 1373,
1352, 1179, 928, 787, 698, 615. 1H NMR (400 MHz, CDCl3): 8.43
(d, J = 2.3 Hz, 1H), 8.27 (d, J = 8.9 Hz, 1H),
8.20 (dd, J = 8.9, 2.3 Hz, 1H), 4.13 (hept, J = 6.8 Hz, 1H),
1.42 (d, J = 6.7 Hz, 6H). 13C NMR (101 MHz, CDCl3):
152.0, 151.8, 146.5, 130.2, 124.3, 121.5, 29.9, 23.8. HRMS
(CI-): Found: 244.0287 ([M+Cl+O] C9H10NO532S
Requires: 244.0274).
-
S12
4. Synthesis of (±)-indoline sulfonamides 6-8a, 6b-f and
6i-q
General Procedure B – Indoline sulfonylation
To a well-stirred solution of (±)-indoline (1.0 eq.),
arylsulfonyl chloride (1.0 eq.) and 4-DMAP-N-oxide (10-20
mol%) or N-methylimidazole (5-20 mol%) in CH2Cl2 under argon was
added DIPEA (2 eq.). The solution was
stirred for several hours at room temperature. The solution was
conc. in vacuo and the crude residue was purified
by FC to afford sulfonylated indolines.
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2-methylindoline
(6a)
Following General Procedure B, (±)-2-methylindoline (5a, 130.2
mg, 1.0 mmol), 2-
isopropyl-4-nitrobenzenesulfonyl chloride (264 mg, 1.0 mmol),
4-DMAP-N-oxide (14 mg,
0.1 mmol) and DIPEA (0.34 mL, 2 mmol) were reacted for 21 h. The
resulting yellow
solution was conc. in vacuo and the crude residue purified by FC
(eluent: 30% CH2Cl2/hexanes) to afford
sulfonamide product as a white solid (298 mg, 0.83 mmol, 83%).
M.p 140-141 °C. IR (film, cm-1): 2964, 1530,
1478, 1348, 1165, 1107, 908, 785, 734, 649. 1H NMR (400 MHz,
CDCl3, ppm): 8.27 (d, J = 2.2 Hz, 1H), 8.08 -
7.96 (m, 2H), 7.40 (dd, J = 7.7, 1.6 Hz, 1H), 7.22 - 7.13 (m,
2H), 7.06 (td, J = 7.3, 6.8, 1.0 Hz, 1H), 4.48 (dqd, J
= 8.6, 6.4, 2.1 Hz, 1H), 3.87 (hept, J = 6.8 Hz, 1H), 3.26 -
3.13 (m, 1H), 2.61 (dd, J = 16.0, 2.1 Hz, 1H), 1.43 (d,
J = 6.4 Hz, 3H), 1.24 (d, J = 6.8 Hz, 3H), 1.04 (d, J = 6.8 Hz,
3H). 13C NMR (101 MHz, CDCl3, ppm): 151.8,
150.3, 143.0, 140.3, 130.6, 130.1, 128.0, 125.8, 124.6, 123.4,
120.7, 116.0, 59.0, 36.3, 30.2, 24.1, 23.5, 22.8.
HRMS (CI+): Found: 361.1219 ([M+H] C18H21N2O432S Requires:
361.1217).
(±)-2-Methyl-1-((4-nitrophenyl)sulfonyl)indoline (7a)[16–18]
Following General Procedure B, (±)-2-methylindoline (5a, 52 mg,
0.39 mmol), 4-
nitrobenzenesulfonyl chloride (103 mg, 0.47 mmol),
4-DMAP-N-oxide (5 mg, 0.039
mmol) and DIPEA (0.14 mL, 0.78 mmol) were reacted for 21 h. The
resulting yellow
solution was conc. in vacuo and the crude residue purified by FC
(eluent: 10% EtOAc2/hexanes) to afford
sulfonamide product as an off white solid (114 mg, 0.36 mmol,
92%). 1H NMR (400 MHz, CDCl3, ppm): 8.25
(d, J = 8.8 Hz, 2H), 7.89 (d, J = 8.8 Hz, 2H), 7.68 (d, J = 8.3
Hz, 1H), 7.25 (d, J = 6.9 Hz, 1H) 7.07-7.13 (m 2H),
4.42 (ddq, J = 9.6, 6.7, 2.8 Hz, 1H), 2.95 (dd, J = 16.7, 9.6
Hz, 1H), 2.51 (dd, J = 16.7, 2.8 Hz, 1H), 1.47 (d, J =
6.7 Hz, 3H). 13C NMR (101 MHz, CDCl3, ppm): 150.7, 144.3, 140.2,
131.8, 128.5, 128.3, 125.8, 125.6, 124.4,
117.3, 59.3, 36.0, 23.8. LRMS (m/z +ES): Found: 319.3 (M+H
C15H15N2O432S Requires: 319.1). Spectroscopic
data in agreement with literature.[16–18]
(±)-2-Methyl-1-((2-nitrophenyl)sulfonyl)indoline (8a)[16,17]
Following General Procedure B, (±)-2-methylindoline (5a, 130.2
mg, 1 mmol), 2-
nitrobenzenesulfonyl chloride (220 mg, 1.0 mmol), 4-DMAP-N-oxide
(14 mg, 0.1 mmol) and
DIPEA (0.34 mL, 2 mmol) were reacted for 21 h. The resulting
yellow solution was conc. in
vacuo and the crude residue purified by FC (eluent: 25%
CH2Cl2/hexanes) to afford sulfonamide
product as a dark red oil (238 mg, 0.75 mmol, 75%). IR (film,
cm-1): 3023, 2983, 1542, 1513, 1210, 1109, 987. 1H
-
S13
NMR (400 MHz, CDCl3, ppm): 7.87 (dd, J = 7.9, 1.2 Hz, 1H), 7.67
(td, J = 7.9, 1.2 Hz, 1H), 7.65-7.61 (m, 3H),
7.25-7.18 (m, 2H), 7.08 (t, J = 7.9 Hz, 1H), 4.82-4.63 (m, 1H),
3.32 (dd, J = 15.9, 9.1 Hz, 1H), 2.61 (dd, 15.9, 2.0
Hz, 1H), 1.44 (d, J = 6.5 Hz, 3H). 13C NMR (101 MHz, Toluene-d7,
ppm): 148.6, 140.4, 133.2, 132.2, 131.6,
130.6, 130.5, 125.9, 124.5, 123.7, 116.0, 59.5, 36.0, 22.9. HRMS
(m/z +ES): Found: 319.0762 (M+H
C15H15N2O432S Requires: 319.0753). Spectroscopic data in
agreement with literature.[16,17]
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2-(((triethylsilyl)oxy)
methyl)indoline (6b)
Following General Procedure B,
(±)-2-(((triethylsilyl)oxy)methyl) indoline (5b, 26.3 mg,
0.1 mmol), 2-isopropyl-4-nitrobenzene-sulfonyl chloride (26.4
mg, 0.1 mmol), NMI (0.4
L, 0.005 mmol, 5 mol%) and DIPEA (20 L, 0.2 mmol) were stirred
for 27 h. The resulting
yellow solution was conc. in vacuo and the crude residue was
purified by FC (eluent: 5% EtOAc/hexanes) to afford
the sulfonamide product as a yellow oil (27 mg, 0.055 mmol,
55%). IR (film, cm-1): 2957, 2875, 1531, 1478, 1461,
1407, 1348, 1240, 1165, 1108, 784, 749, 731. 1H NMR (400 MHz,
CDCl3, ppm): 8.29 (dd, J = 2.0, 0.8 Hz, 1H),
8.10 – 8.00 (m, 2H), 7.40 (dd, J = 8.4, 1.1 Hz, 1H), 7.23 – 7.14
(m, 2H), 7.06 (td, J = 7.4, 1.1 Hz, 1H), 4.38 (dtd,
J = 7.7, 5.6, 4.1 Hz, 1H), 3.95 – 3.80 (m, 2H), 3.66 (dd, J =
10.1, 7.8 Hz, 1H), 3.07 (d, J = 5.6 Hz, 2H), 1.27 (d, J
= 6.8 Hz, 3H), 1.04 (d, J = 6.8 Hz, 3H), 0.91 (t, J = 7.9 Hz,
9H), 0.65 – 0.49 (m, 6H. 13C NMR (101 MHz, CDCl3,
ppm): 151.9, 150.4, 142.9, 141.3, 131.3, 130.2, 127.8, 125.7,
124.9, 123.6, 120.8, 116.0, 64.7, 63.4, 31.3, 30.5,
24.3, 23.6, 6.8, 4.4. HRMS (ES+): Found: 491.2045 ([M+H]
C15H25NOSi Requires: 491.2036).
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2-(((triisopropylsilyl)
oxy)methyl)indoline (6c)
Following General Procedure B,
(±)-2-(((triisopropylsilyl)oxy)methyl)indoline (5c, 30
mg, 0.1 mmol), 2-isopropyl-4-nitrobenzenesulfonyl chloride (26.4
mg, 0.1 mmol), NMI (2
L, 0.02 mmol) and DIPEA (34 L, 0.2 mmol) were reacted for 20 h.
The resulting yellow
solution was conc. in vacuo and the crude residue was purified
by FC (eluent: 5% Et2O/hexanes) to afford the
sulfonamide product as a colourless oil (49 mg, 0.92 mmol, 92%).
IR (film, cm-1): 2943, 2866, 1531, 1479, 1462,
1348, 1165, 1109, 988, 881, 785, 623, 575; 1H NMR (400 MHz,
CDCl3, ppm): 8.26 (d, J = 2.3 Hz, 1H), 8.06 -
7.94 (m, 2H), 7.41 (d, J = 8.0 Hz, 1H), 7.15 (t, J = 7.7 Hz,
2H), 7.04 (t, J = 7.4 Hz, 1H), 4.35 (tt, J = 7.1, 3.2 Hz,
1H), 3.97 (dd, J = 9.9, 4.0 Hz, 1H), 3.86 (p, J = 6.8 Hz, 1H),
3.77 (dd, J = 9.9, 7.5 Hz, 1H), 3.17 - 2.96 (m, 2H),
1.31 - 1.21 (m, 6H), 1.11 - 0.93 (m, 21H). 13C NMR (101 MHz,
CDCl3, ppm): 151.8, 150.2, 142.7, 141.3, 131.3,
130.0, 127.7, 125.5, 124.8, 123.5, 120.7, 115.9, 65.4, 63.3,
31.1, 30.3, 24.2, 23.5, 17.9, 11.89. HRMS (ES-): Found:
531.2356 ([M-H] C27H39N2O5Si32S Requires: 531.2349).
(±)-2-(((tert-Butyldimethylsilyl)oxy)methyl)-1-((2-ethyl-4-nitrophenyl)sulfonyl)indoline
(6d)
Following General Procedure B,
(±)-2-(((tert-butyldimethylsilyl)oxy)methyl)indoline
(5d, 26 mg, 0.1 mmol), 2-isopropyl-4-nitrobenzenesulfonyl
chloride (26.4 mg, 0.1 mmol),
NMI (2 L, 0.02 mmol) and DIPEA (34 L, 0.2 mmol) were reacted for
20 h. The resulting
yellow solution was conc. in vacuo and the crude residue was
purified by FC (eluent: 5% Et2O/hexanes) to afford
the sulfonamide product as a colourless oil (37 mg, 0.76 mmol,
76%). IR (film, cm-1): 2955, 2930, 2857, 1531,
1256, 1348, 1165, 1107, 837, 783, 644, 623, 573; 1H NMR (400
MHz, CDCl3, ppm): 8.27 (d, J = 2.1 Hz, 1H),
8.06 - 7.96 (m, 2H), 7.36 (d, J = 7.9 Hz, 1H), 7.21 - 7.10 (m ,
2H), 7.03 (t, J = 7.4 Hz, 1H), 4.37 (hept, J = 6.8 Hz,
1H), 3.93 - 3.81 (m, 2H), 3.69 (dd, J = 10.3, 6.9 Hz, 1H), 3.15
- 2.97 (m, 2H), 1.26 (d, J = 6.8 Hz, 3H), 1.03 (d, J
= 6.7 Hz, 3H), 0.78 (s, 9H), 0.01 (d, J = 17.2 Hz, 6H); 13C NMR
(101 MHz, CDCl3, ppm): 151.7, 150.2, 142.9,
-
S14
141.3, 131.3, 129.9, 127.7, 125.5, 124.7, 123.5, 120.7, 115.7,
65.1, 63.3, 31.2, 30.3, 25.7, 24.2, 23.5, 18.1, -5.5.
HRMS (CI+): Found: 491.2025 ([M+H] C24H35N2O532SSi Requires:
491.2030).
(±)-2-Isopropyl-1-((2-isopropyl-4-nitrophenyl)sulfonyl)indoline
(6e)
Following General Procedure B, (±)-2-isopropylindoline (5e, 14.5
mg, 0.09 mmol), 2-
isopropyl-4-nitrobenzenesulfonyl chloride (23.6 mg, 0.09 mmol),
4-DMAP-N-oxide (2.5
mg, 0.02 mmol 20 mol%) and DIPEA (34 L, 0.2 mmol) were reacted
for 16.5h. The
resulting yellow solution was conc. in vacuo and the crude
residue purified by FC (eluent:
20% EtOAc/hexanes) to afford sulfonamide product as a yellow oil
(24 mg, 0.061 mmol, 68%). IR (film, cm-1):
3101, 3046, 2965, 2936, 2874, 1530, 1479, 1462, 1348, 1167,
1096, 785, 698. 1H NMR (400 MHz, CDCl3, ppm):
8.23 (d, J = 1.8 Hz, 1H), 8.06 - 7.99 (m, 2H), 7.46 (d, J = 8.1
Hz, 1H), 7.17 (t, J = 7.7 Hz, 1H), 7.11 (d, J = 7.6
Hz, 1H), 7.04 (td, J = 7.4, 1.0 Hz, 1H), 4.15 (ddd, J = 9.1,
5.1, 2.4 Hz, 1H), 3.82 (hept, J = 6.8 Hz, 1H), 2.83 (m,
1H), 2.73 (dd, J = 16.6, 2.5 Hz, 1H), 2.15 (hept, J = 6.8, 1H),
1.21 (d, J = 6.8 Hz, 3H), 0.95 (m, 6H), 0.83 (d, J =
6.8 Hz, 3H). 13C NMR (101 MHz, CDCl3, ppm): 152.0, 150.4, 142.4,
141.6, 132.6, 130.9, 127.9, 125.3, 125.1,
123.5, 120.7, 117.0, 68.1, 33.3, 30.4, 30.2, 24.4, 23.5, 18.7,
16.4. HRMS (CI+): Found: 389.1530 ([M+H]
C20H25N2O432S Requires: 389.1530).
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2-n-butylindoline
(6f)
Following General Procedure B, (±)-2-n-butylindoline (5f, 15.7
mg, 0.09 mmol), 2-
isopropyl-4-nitrobenzenesulfonyl chloride (23.6 mg, 0.09 mmol),
4-DMAP-N-oxide (2.5
mg, 0.018 mmol, 20 mol%) and DIPEA (31 L, 0.18 mmol) were
reacted for 24 h. The
resulting yellow solution was conc. in vacuo and the crude
residue purified by FC (eluent: 30% CH2Cl2/hexanes)
to afford sulfonamide product as a yellow oil (28 mg, 0.07 mmol,
76%). IR (film, cm-1): 2959, 2932, 2872, 1530,
1462, 1348, 1165, 785, 696, 623, 577. 1H NMR (400 MHz, CDCl3,
ppm): 8.24 (d, J = 2.1 Hz, 1H), 8.08 - 7.96
(m, 2H), 7.43 (d, J = 8.0 Hz, 1H), 7.23 - 7.10 (m, 2H), 7.05
(td, J = 7.4, 1.0 Hz, 1H), 4.31 (tdd, J = 8.8, 5.1, 1.9
Hz, 1H), 3.83 (hept, J = 6.9 Hz, 1H), 3.00 (ddt, J = 16.0, 9.1,
1.2 Hz, 1H), 2.67 (dd, J = 16.0, 1.7 Hz, 1H), 1.81
(dtd, J = 13.1, 7.8, 7.2, 5.1 Hz, 1H), 1.72 - 1.58 (m, 1H), 1.43
- 1.27 (m, 4H), 1.23 (d, J = 6.7 Hz, 3H), 0.98 (d, J
= 6.8 Hz, 3H), 0.89 (t, J = 7.0 Hz, 3H). 13C NMR (101 MHz,
CDCl3, ppm): 151.9, 150.4, 142.9, 140.8, 131.8,
130.6, 128.0, 125.7, 125.1, 123.5, 120.8, 116.9, 63.4, 36.0,
34.1, 30.4, 27.2, 24.4, 23.6, 22.6, 14.1. HRMS (ES-):
Found: 401.1542 ([M-H] C21H25N2O432S Requires: 401.1535).
(±)-5-Chloro-1-((2-isopropyl-4-nitrophenyl)sulfonyl)-2-methylindoline
(6i)
Following General Procedure B, (±)-5-chloro-2-methylindoline
(5i, 20 mg, 0.12
mmol), 2-isopropyl-4-nitrobenzenesulfonyl chloride (31 mg, 0.12
mmol) and NMI (1.5
L, 0.012 mmol, 10 mol%) and DIPEA (44 L, 0.24 mmol) were reacted
for 16 h. The
resulting yellow solution was conc. in vacuo and the crude
residue was purified by FC (eluent: 30%
EtOAc/hexanes) to afford the sulfonamide product as a white oily
solid (24 mg, 0.063 mmol, 32%). IR (film, cm-
1): 2965, 2932, 2870, 1531, 1474, 1348, 1165, 785, 733, 698,
631, 583; 1H NMR (400 MHz, CDCl3, ppm): 8.28
(d, J = 2.3 Hz, 1H), 8.06 (dd, J = 8.8, 2.3 Hz, 1H), 7.98 (d, J
= 8.8 Hz, 1H), 7.33 (d, J = 9.1 Hz, 1H), 7.19 - 7.10
(m, 2H), 4.48 (dqd, J = 8.8, 6.4, 2.2 Hz, 1H), 3.83 (hept, J =
6.8 Hz, 1H), 3.19 (dd, J = 16.3, 9.2 Hz, 1H), 2.60 (dd,
J = 16.4, 2.2 Hz, 1H), 1.42 (d, J = 6.5 Hz, 3H), 1.25 (d, J =
6.8 Hz, 1H), 1.08 (d, J = 6.7 Hz, 1H). 13C NMR (101
-
S15
MHz, CDCl3, ppm): 151.9, 150.5, 142.8, 139.2, 132.7, 130.2,
130.0, 128.2, 126.1, 123.7, 120.9, 117.0, 59.5,
36.2, 30.3, 24.2, 23.7, 22.9. HRMS (ES+): Found: 395.0759 ([M+H]
C18H2035ClO4N232S Requires: 395.0754.
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2,5-methylindoline
(6j)
Following General Procedure B: (±)-2,5-dimethylindoline (5j, 25
mg, 0.17 mmol), 2-
isopropyl-4-nitrobenzenesulfonyl chloride (45 mg, 0.17 mmol) and
NMI (1.5 L, 0.012
mmol, 7 mol%) and DIPEA (59 L, 0.34 mmol) were stirred for 21.5
h. The resulting
yellow solution was conc. in vacuo and the crude residue was
purified by FC (eluent: 50% CH2Cl2/hexanes) to
afford the sulfonamide product as a white solid (53 mg, 0.15
mmol, 87%). M.p 154-155 °C. IR (film, cm-1): 3100,
2967, 2930, 2870, 1530, 1487, 1346, 1163, 785, 733, 637, 584. 1H
NMR (400 MHz, CDCl3, ppm): 8.26 (d, J =
2.3 Hz, 1H), 8.03 (dd, J = 8.7, 2.3 Hz, 1H), 7.98 (d, J = 8.7
Hz, 1H), 7.28 (d, J = 8.6 Hz, 1H), 7.02-6.94 (m, 2H),
4.46 (dqd, J = 8.8, 6.5, 2.1 Hz, 1H), 3.88 (hept, J = 6.8 Hz,
1H), 3.14 (dd, J = 16.1, 9.1 Hz, 1H), 2.55 (dd, J = 15.9,
2.0 Hz, 1H), 2.29 (s, 3H), 1.41 (d, J = 6.5 Hz, 3H), 1.24 (d, J
= 6.7 Hz, 3H), 1.04 (d, J = 6.7 Hz, 3H); 13C NMR
(101 MHz, CDCl3, ppm): 151.9, 150.4, 143.2, 138.0, 134.7, 131.0,
130.2, 128.6, 126.5, 123.5, 120.8, 116.1,
59.2, 36.4, 30.3, 24.3, 23.6, 22.9, 21.1. HRMS (CI+): Found:
375.1383 ([M+H] C19H23O4N232S Requires:
375.1373.
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-5-methoxy-2-methylindoline
(6k)
Following General Procedure B, (±)-5-methoxy-2-methylindoline
(5k, 16 mg, 0.1
mmol), 2-isopropyl-4-nitrobenzenesulfonyl chloride (26.4 mg, 0.1
mmol), NMI (2 L,
0.02 mmol) and DIPEA (34 L, 0.2 mmol) were reacted for 14 h. The
resulting yellow
solution was conc. in vacuo and the crude residue was purified
by FC (eluent: 50% - 100% CH2Cl2/hexanes) to
afford the sulfonamide product as a yellow oil (31 mg, 0.079
mmol, 79%). IR (film, cm-1): 2966, 1596, 1529,
1486, 1347, 1262, 1164, 1033, 904, 811, 784, 636. 1H NMR (400
MHz, CDCl3, ppm): 8.25 (d, J = 2.2 Hz, 1H),
8.09 - 7.90 (m, 2H), 7.35 (d, J = 8.5 Hz, 1H), 6.73 (d, J = 8.9
Hz, 2H), 4.42 (dtt, J = 8.6, 6.6, 3.3 Hz, 1H), 3.86
(hept, J = 6.9 Hz, 1H), 3.77 (s, 3H), 3.08 (dd, J = 16.1, 9.0
Hz, 1H), 2.51 (dd, J = 16.1, 2.0 Hz, 1H), 1.39 (d, J =
6.5 Hz, 3H), 1.24 (d, J = 6.8 Hz, 3H), 1.01 (d, J = 6.8 Hz, 3H);
13C NMR (101 MHz, CDCl3): 157.5, 151.8,
150.2, 142.8, 133.5, 132.8, 130.3, 123.4, 120.7, 117.6, 113.0,
111.6, 59.2, 55.7, 36.4, 30.3, 24.3, 23.4, 22.7. HRMS
(ES+): Found: 391.1250 ([M+H] C19H23O5N232S Requires:
391.1249.
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-N,N,2-trimethylindolin-6-amine
(6l)
Following General Procedure B,
(±)-N,N-2-trimethylindolin-6-amine (5l, 15 mg,
0.085 mmol), 2-isopropyl-4-nitrobenzenesulfonyl chloride (34 mg,
0.128 mmol, 1.5
eq.) and 4-DMAP-N-oxide (2.4 mg, 0.2 mmol) and DIPEA (30 L, 0.17
mmol) were
reacted for 4.5 h. The resulting yellow solution was conc. in
vacuo and the crude residue purified by FC (eluent:
50% CH2Cl2/0.1% Et3N/hexanes) to afford sulfonamide product as
an orange solid (24 mg, 0.058 mmol, 69%).
M.p 136-137 °C. IR (film, cm-1): 2964, 1619, 1530, 1461, 1347,
1164, 1109, 784, 630. 1H NMR (400 MHz, CDCl3,
ppm): 8.26 (d, J = 2.3 Hz, 1H), 8.03 (dd, J = 8.7, 2.2 Hz, 1H),
7.98 (d, J = 8.8 Hz, 1H), 7.00 (d, J = 8.3 Hz, 1H),
6.83 (d, J = 2.4 Hz, 1H), 6.42 (dd, J = 8.3, 2.4 Hz, 1H), 4.47
(dqd, J = 8.6, 6.5, 2.0 Hz, 1H), 3.93 (h, J = 6.8 Hz,
1H), 3.09 (ddd, J = 15.4, 9.1, 1.3 Hz, 1H), 2.91 (s, 6H), 2.49
(dd, J = 15.4, 2.0 Hz, 1H), 1.43 (d, J = 6.4 Hz, 3H),
1.24 (d, J = 6.8 Hz, 3H), 1.07 (d, J = 6.8 Hz, 3H). 13C NMR (101
MHz, CDCl3, ppm): 151.8, 151.0, 150.2, 143.4,
-
S16
141.3, 130.0, 125.8, 123.3, 120.6, 118.0, 109.1, 100.8, 59.9,
40.9, 35.3, 30.1, 24.1, 23.5, 23.0. HRMS (ES+):
Found: 404.1655 ([M+H] C20H26N3O432S Requires: 404.1644).
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-cis-2,3-dimethylindoline
(6m)
Following General Procedure B, (±)-cis-2,3-dimethylindoline (5m,
15 mg, 0.1 mmol), 2-
isopropyl-4-nitrobenzenesulfonyl chloride (40 mg, 0.15 mmol, 1.5
eq.), 4-DMAP-N-oxide
(1.5 mg, 0.1 mmol, 10 mol%) and NEt3 (28 L, 0.20 mmol) were
reacted for 4.5 h. The
resulting yellow solution was conc. in vacuo and the crude
residue was purified by FC
(eluent: 25% CH2Cl2/hexanes) to afford sulfonamide product as a
yellow oil (29 mg, 0.078 mmol, 76%). IR (film,
cm-1): 3107, 3095, 2922, 1660, 1609, 912, 892. 1H NMR (400 MHz,
CDCl3, ppm): δ 8.28 (d, J = 2.2 Hz, 1H),
8.15-8.07 (m, 2H), 7.42 (d, J = 8.0 Hz, 1H), 7.25-7.20 (m, 1H),
7.13-7.09 (m, 2H), 4.49 (dq, J = 8.6, 6.7 Hz, 1H),
3.86 (p, J = 6.7 Hz, 1H), 3.28 (qd, J = 7.8, 6.4 Hz, 1H), 1.30
(d, J = 6.7 Hz, 3H), 1.26 (dd, J = 7.0, 3.1 Hz, 6H),
1.00 (d, J = 6.7 Hz, 3H). 13C NMR (100 MHz, CDCl3, ppm): δ
151.7, 150.3, 143.2, 139.8, 136.1, 130.4, 128.0,
124.9, 124.0, 123.4, 120.7, 116.3, 63.7, 38.5, 30.3, 24.6, 23.4,
15.9, 12.0. HRMS (m/z +ES): Found: 375.1369
(M+H C19H23N2O432S Requires: 375.1379).
(±)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-trans-2,3-dimethylindoline
(6n)
Following General Procedure A, (±)-trans-2,3-dimethylindoline
(5n, 15 mg, 0.1 mmol),
2-isopropyl-4-nitrobenzenesulfonyl chloride (40 mg, 0.15 mmol,
1.5 eq.), 4-DMAP-N-
oxide (1.5 mg, 0.1 mmol, 10 mol%) and NEt3 (28 L, 0.20 mmol)
were reacted for 4.5 h.
The resulting yellow solution was conc. in vacuo and the crude
residue was purified by FC
(eluent: 25% CH2Cl2/hexanes) to afford sulfonamide product as a
yellow oil (21 mg, 0.056 mmol, 55%). IR (film,
cm-1): 3013, 3007, 2893, 1609, 1577, 1483, 928, 837, 716. 1H NMR
(400 MHz, CDCl3, ppm): δ 8.30 (d, J = 2.0
Hz, 1H), 8.13-8.07 (m, 2H), 7.50 (d, J = 8.2 Hz, 1H), 7.27-7.22
(m, 1H), 7.1 (d, J = 7.4 Hz, 1H), 7.10 (td, J = 7.4,
1.0 Hz, 1H), 4.01-3.89 (m, 2H), 2.84 (qd, J = 7.1, 2.4 Hz, 1H),
1.44 (d, J = 6.5 Hz, 3H), 1.30 (d, J = 6.5 Hz, 3H),
0.98 (d, J = 6.8 Hz, 3H), 0.87 (d, J = 7.1 Hz, 3H).13C NMR (100
MHz, CDCl3, ppm): δ 151.8, 150.2, 142.5, 139.6,
136.1, 130.7, 128.1, 125.0, 124.7, 124.3, 123.4, 120.6, 116.1,
66.5, 43.7, 30.2, 24.3, 23.4, 22.2, 21.6. HRMS (m/z
+ES): Found: 375.1372 (M+H C19H23N2O432SRequires: 375.1379).
(±)-cis-4-((2-Isopropyl-4-nitrophenyl)sulfonyl)-1,2,3,3a,4,8b-hexahydr-ocyclopenta[b]indole
(6o)
Following General Procedure B,
(±)-cis-1,2,3,3a,4,8b-hexahydrocyclopenta[b]indole (5o,
15.9 mg, 0.1 mmol), 2-isopropyl-4-nitrobenzenesulfonyl chloride
(26.0 mg, 0.1 mmol) and
4-DMAP-N-oxide (1.4 mg, 0.01 mmol) and DIPEA (34 L, 0.2 mmol)
were reacted for 26
h. The resulting yellow solution was conc. in vacuo and the
crude residue purified by FC
(eluent: 30% CH2Cl2/hexanes) to afford sulfonamide product as a
yellow solid (28 mg, 0.072 mmol, 72%). IR
(film, cm-1): 3107, 2961, 2870, 1530, 1477, 1460, 1348, 1163,
839, 785, 746, 623. 1H NMR (400 MHz, CDCl3,
ppm): 8.29 (d, J = 2.3 Hz, 1H), 8.02 (dd, J = 8.8, 2.4 Hz, 1H),
7.86 (d, J = 8.8 Hz, 1H), 7.33 (d, J = 8.3 Hz, 1H),
7.17 – 7.11 (m, 2H), 7.04 (td, J = 7.4, 1.1 Hz, 1H), 4.66 (ddd,
J = 9.6, 7.2, 2.9 Hz, 1H), 3.94 (h, J = 6.8 Hz, 1H),
3.84 (td, J = 8.4, 2.4 Hz, 1H), 2.20 - 2.09 (m, 1H), 2.06 - 1.92
(m, 2H), 1.91 - 1.82 (m, 1H), 1.66 (dtt, J = 12.6,
6.3, 3.8 Hz, 1H), 1.46 (dtt, J = 12.7, 10.2, 6.4 Hz, 1H), 1.27
(d, J = 6.8 Hz, 3H), 1.13 (d, J = 6.7 Hz, 3H). 13C NMR
(101 MHz, CDCl3, ppm): 152.0, 150.3, 143.1, 142.0, 134.8, 129.5,
128.1, 125.2, 124.6, 123.7, 120.8, 114.3,
-
S17
68.0, 45.7, 36.2, 34.3, 30.2, 24.1, 24.0, 23.9. HRMS (CI+):
Found: 387.1373 ([M+H] C20H23O4N232S Requires:
387.1373).
(±)-cis-9-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2,3,4,4a,9,9a-hexahydro-1H-carbazole
(6p)
Following General Procedure B,
(±)-cis-2,3,4,4a,9,9a-hexahydro-1H-carbazole (5p, 13
mg, 0.075 mmol), 2-isopropyl-4-nitrobenzenesulfonyl chloride (28
mg, 0.11 mmol, 1.5 eq.),
4-4-DMAP-N-oxide (1.0 mg, 0.1 mmol, 15 mol%) and DIPEA (30 L,
0.17 mmol) were
reacted for 4.5 h. The resulting yellow solution was conc. in
vacuo and the crude residue
was purified by FC (20% CH2Cl2:hexanes) to afford product as an
oily solid (20 mg, 0.05 mmol, 68%). IR (film,
cm-1): 3013, 3007, 2988, 1657, 1438, 1232, 932, 889. 1H NMR (400
MHz, CDCl3): 8.25 (d, J = 2.3 Hz, 1H),
8.17 (d, J = 8.7 Hz, 1H), 8.07 (dd, J = 8.7, 2.3 Hz, 1H), 7.38
(d, J = 7.9 Hz, 1H), 7.23 – 7.16 (m, 1H), 7.15 – 7.04
(m, 2H), 4.32 (ddd, J = 10.6, 7.4, 6.1 Hz, 1H), 3.86 (hept, J =
6.8 Hz, 1H), 3.25 – 3.12 (m, 1H), 2.25 – 2.16 (m,
1H), 2.15 – 2.06 (m, 1H), 1.79 – 1.57 (m, 2H), 1.56 – 1.39 (m,
2H), 1.31 – 1.07 (m, 2H), 1.23 (d, J = 6.8 Hz, 3H),
0.99 (d, J = 6.8 Hz, 3H). 13C NMR (101 MHz, CDCl3): 151.83,
150.46, 143.56, 140.91, 134.96, 130.68, 127.90,
124.95, 123.57, 123.51, 120.87, 116.90, 64.56, 40.36, 30.30,
29.11, 24.43, 24.31, 23.55, 22.75, 20.71. HRMS
(ES+): Found: 401.1461 ([M+H] C21H25N2O432S Requires:
401.1457).
(±)-cis-tert-Butyl-9-((2-isopropyl-4-nitrophenyl)sulfonyl)-4,4a,9,9a-tetrahydro-1H-pyrido[3,4-b]indole-
2(3H)-carboxylate (6q)
Following General Procedure B, (±)-cis-tert-butyl
4,4a,9,9a-tetrahydro-1H-pyrido[3,4-
b]indole-2(3H)-carboxylate (5q, 20 mg, 0.072 mmol),
2-isopropyl-4-nitrobenzenesulfonyl
chloride (28 mg, 0.11 mmol, 1.5 eq.), 4-DMAP-N-oxide (1.0 mg,
0.1 mmol, 15 mol%) and
DIPEA (30 L, 0.17 mmol) were reacted for 4.5 h. The resulting
yellow solution was conc.
in vacuo and the crude residue was purified by FC (eluent: 0 -
20% EtOAc/hexanes) to afford sulfonamide product
as a yellow oil (31 mg, 0.062 mmol, 87%). IR (film, cm-1): 2972,
1691, 1602, 1530, 1476, 1460, 1408, 1279, 1165,
1113, 1055, 982, 784. 1H NMR (400 MHz, CDCl3): 8.27 (d, J = 2.3
Hz, 1H), 8.08 - 7.96 (m, 2H), 7.36 (d, J =
8.1 Hz, 1H), 7.20 (t, J = 7.6 Hz, 1H), 7.16 - 7.05 (m, 2H), 4.45
(s, 1H), 4.04 - 3.79 (m, 2H), 3.63 - 3.19 (m, 3H),
2.96 (ddd, J = 12.9, 10.6, 4.6 Hz, 1H), 2.19 – 2.03 (m, 2H),
1.38 (s, 9H), 1.26 (d, J = 6.7 Hz, 3H), 1.04 (d, J = 6.7
Hz, 3H). 13C NMR (101 MHz, CDCl3): 155.0, 151.9, 150.5, 142.9,
141.4, 132.8, 130.1, 128.6, 125.2, 124.3,
123.6, 121.0, 116.0, 80.2, 61.4, 60.5, 39.5, 38.4, 30.3, 28.5,
24.2, 23.9, 23.7. HRMS (ES+): Found: 502.2037
([M+H] C25H32N3O632S Requires: 502.2012).
-
S18
5. Synthesis and resolution of catalysts 4a and 4b
CATALYST 4a
2-(2,4-Bis(trifluoromethyl)phenyl)-4-chloropyridine
2,4-Bis(trifluoromethyl)benzeneboronic acid (2.54 g, 10.14 mmol,
1.5 eq.), potassium
phosphate (2.86 g, 13.52 mmol, 2 eq.) and
tetrakis(triphenylphosphine)palladium(0) (0.20 g,
0.20 mmol, 3 mol%) were dissolved in a degassed 1:3 H2O:THF
solvent system. After the
addition of 2,4-dichloropyridine (1.00 g, 6.76 mmol) the orange
solution was heated under
reflux (90 °C) for 16 h. The reaction mixture was then allowed
to cool to room temperature and EtOAc (10 mL)
was added. The resulting organic layer was washed with brine
solution (2 × 20 mL), separated, dried over MgSO4
and conc. in vacuo. The resulting residue was purified by FC
(0-20% EtOAc:hexanes) to afford product as an off-
white powder (1.78 g, 5.48 mmol, 81%). 1H NMR (400 MHz, CDCl3,
ppm): δ 8.67 (d, J = 5.5 Hz, 1H), 8.07 (s,
1H), 7.92 (d, J = 7.9 Hz, 1H), 7.68 (d, J = 8.0 Hz, 1H), 7.49
(d, J = 1.7 Hz, 1H), 7.43 (dd, J = 5.6, 2.0 Hz, 1H).
Spectroscopic data in agreement with literature.[19]
2-(2-Bromo-4,6-bis(trifluoromethyl)phenyl)-4-chloropyridine
2-(2,4-Bis(trifluoromethyl)phenyl)-4-chloropyridine (0.76 g,
2.49 mmol), N-bromosuccinimide
(0.89 g, 4.98 mmol, 2 eq.) and
tetrakis(triphenylphosphine)palladium(0) (0.15 g, 0.13 mmol, 5
mol%) were added to a microwave vial. After acetonitrile (14 mL)
was added, the reaction
mixture was heated to 180 °C for 20 min in a microwave. The
resulting brown solution was
purified by FC (0-15% EtOAc:hexanes) to provide
2-(2-bromo-4,6-bis(trifluoromethyl)phenyl)-4-chloropyridine
as a white crystalline solid (0.75 g, 1.87 mmol, 38%). M.p. =
137-139 oC. IR (film, cm-1): 3097, 3033, 2932, 2837,
1517, 1433, 984, 837. 1H NMR (400 MHz, CDCl3, ppm): δ 8.67 (d, J
= 5.4 Hz, 1H), 8.18-8.17 (m, 1H), 8.03 (d, J
= 1.2 Hz, 1H), 7.45 (dd, J = 5.4, 2.0 Hz, 1H), 7.36 (d, J = 1.9
Hz, 1H). 13C (100 MHz, CDCl3): δ 122.5, 124.1,
124.9, 126.2, 126.4, 133.3, 139.8, 144.4, 150.4, 156.4. 19F (377
MHz, CDCl3): δ -58.3, 63.1. HRMS (ES+): Found:
403.9201 ([M+H] C13H679Br35ClF6N Requires: 403.9198).
2-(2-Bromo-4,6-bis(trifluoromethyl)phenyl)-4-chloropyridine-N-oxide
2-(2-bromo-4,6-bis(trifluoromethyl)phenyl)-4-chloropyridine
(0.250 g, 0.649 mmol) was
dissolved in a solution of dichloromethane (5 mL) and distilled
water (2 mL) and cooled to 0
°C. Sodium bicarbonate (0.109 g, 1.30 mmol, 2 eq.) was added and
a large fraction of m-CPBA
(0.224 g, 1.30 mmol, 2 eq.). Once the reaction mixture was
warmed to room temperature, the
rest of the m-CPBA was added and the solution was heated to
reflux for 16 h. The reaction was then quenched
with 10 mL of Na2SO4 solution and the organic phase was washed
with NaHCO3 (10 mL) and brine solution (20
mL) adding CH2Cl2 (3 × 15 mL) before each wash. The resulting
solution was dried over magnesium sulfate,
concentrated by rotary evaporation and purified by FC (65%
EtOAc:hexanes) to afford product as an off-white
oil, which solidified upon drying in vacuo (0.210 g, 0.501 mmol,
77%). M.p. = 81-83 oC. IR (film, cm-1): 2932,
1450, 1404, 1335, 1265. 1H NMR (400 MHz, CDCl3, ppm): δ 8.29 (d,
J = 7.0 Hz, 1H), 8.19 (s, 1H), 8.04 (s, 1H),
7.42 (dd, J = 7.0, 3.0 Hz, 1H), 7.29 (s, 1H). 13C (100 MHz,
CDCl3, ppm): δ 146.2, 140.6, 135.2, 133.8, 133.4,
133.3, 131.0, 129.6, 127.5, 127.1, 122.8. 19F (377 MHz, CDCl3,
ppm): δ -60.6, -63.1. HRMS (ES+): Found:
419.9151 ([M+H] C13H6779Br35ClF6NO Requires: 419.9147).
-
S19
2-(2-Bromo-4,6-bis(trifluoromethyl)phenyl)-4-(dimethylamino)pyridine-N-oxide
2-(2-Bromo-4,6-bis(trifluoromethyl)phenyl)-4-chloropyridine-N-oxide
(0.111 g, 0.264 mmol)
was dissolved in MeCN (1 mL) in a microwave vial. Dimethylamine
(60% w.t. in water, 1.2
mL) was added before the reaction mixture was heated to 100 °C
for 30 min in a microwave.
The resulting pale yellow solution was concentrated by rotary
evaporation and purified by FC
(50% i-PrOH /EtOAc) to provide a yellow solid (0.104 g, 0.24
mmol, 92%). M.p = 67-68 oC. IR (film, cm-1): 2932,
1450, 1404, 1335, 1265. 1H NMR (400 MHz, CDCl3, ppm): δ 8.17 (m,
2H), 8.02 (s, 1H), 6.64 (dd, J = 7.5, 3.6
Hz, 1H), 6.43 (d, J = 3.6 Hz, 1H), 3.08 (s, 6H). 13C (100 MHz,
CDCl3) 147.9, 144.7, 139.8, 137.0, 133.2, 132.8
(q, 2JC-F = 34.6 Hz), 132.0 (q, 2JC-F = 32.4 Hz), 127.3, 123.6,
122.5, 120.9, 108.7, 39.9. 19F (376.7 MHz, CDCl3) -
60.1 (s), -63.2 (s). HRMS (ES+): Found: 428.9961 ([M+H]
C15H1179BrF6NO Requires: 428.9959).
(±)-4-(Dimethylamino)-2-(5’-phenyl-3,5-bis(trifluoromethyl)-[1,1':3',1''-terphenyl]-2-yl)pyridine-N-oxide
(4a)
2-(2-Bromo-4,6-bis(trifluoromethyl)phenyl)-4-(dimethylamino)pyridine-N-oxide
(0.500 g,
1.17 mmol) was dissolved in n-butanol (5 mL) and degassed
overnight. It was then added to a
vacuum dried mixture of tris(dibenzylideneacetone)dipalladium
(0.080 g, 0.087 mmol, 7.5
mol%), SPhos (0.072 g, 0.75 mmol, 0.15 eq.), anhydrous
tripotassium phosphate (0.742 g,
3.50 mmol, 3 eq.) and 5’-m-terphenylboronic acid (0.639 g, 2.33
mmol, 2 eq.) under a nitrogen atmosphere. The
reaction mixture was heated to 90 °C for 72 h, then quenched by
the addition of H2O (10 mL) and extracted from
H2O (10 mL) with CH2Cl2 (3 × 15 mL). The organic layer was dried
over MgSO4, concentrated by rotary
evaporation and purified by flash FC (0-20% i-PrOH:EtOAc) to
obtain product as a yellow solid (339 mg, 0.59
mmol, 50%). M.p = 87-95 oC. 1H NMR (400 MHz, CDCl3, ppm): δ 8.10
(s, 1H), 8.04-8.02 (m, 2H), 7.79-7.77 (m,
3H), 7.64-7.62 (m, 4H), 7.49-7.45 (m, 4H), 7.41-7.37 (m, 2H),
6.43 (dd, J = 7.5, 3.5 Hz, 1H), 6.29 (d, J = 3.5 Hz,
1H). 13C NMR (100 MHz, CDCl3, ppm): δ 145.1, 141.6 (2s), 140.2,
139.3, 139.2, 131.8 (2JC-F = 34 Hz), 130.4,
128.9, 127.7, 127.1, 126.1, 125.1, 122.3, 123.4 (2JC-F = 271
Hz), 123.0 (2JC-F = 269 Hz), 118.9, 118.7, 109.6, 108.4,
39.7. HRMS (ES+): Found: 579.1869 ([M+H] C33H25N2OF6 Requires:
579.1871).
The racemic catalyst (±)-4a was resolved using semi-prep HPLC
(OD-H, 1 × 25 cm I.D., 3.3 mL/min, i-
PrOH:EtOAc:hexanes 92:4:4, 25 °C) and the enantiomers collected:
(-)-4a: Rt = 46.2 min. (+)-4a: Rt = 52.2 min.
Each of the collected enantiomers were analysed using analytical
HPLC (OD-H, 0.46 × 25 cm, 0.7 mL/min, i-
PrOH: EtOAc:hexanes 92:4:4, 20 oC):
(-)-4a: Rt = 49.0 min; >99% ee.
-
S20
(+)-4a: Rt = 55.2 min; >99% ee; []D27 +49.5 (c = 0.2,
CHCl3).
CATALYST 4b
2,4-Diiodoaniline[20]
Aniline (1.82 mL, 20 mmol, 1 eq.) in MeOH (1 L) was added to a
well stirred solution of NaI (11.99
g, 80 mmol, 4 eq.) and NaClO2 (3.62 g, 40 mmol, 2 eq.) in H2O (1
L). Then, HCl (aq. 12 M, 5 mL,
60 mmol, 3 eq.) was added. After 6.5 h, H2O (1 L) was added and
the solution was extracted with
EtOAc (250 mL 10). The combined organic phase was stirred with a
brine solution (1 L) with added Na2S2O5
(10 g) to remove iodine. The phases were separated and the
organic phase dried over MgSO4 and conc. in vacuo.
The crude residue was purified by FC (eluent: 10% EtOAc/hexanes)
to afford 2,4-diiodoaniline as a red solid (2.98
g, 8.6 mmol, 43%).1H NMR (400 MHz, CDCl3, ppm): 7.89 (d, J = 1.9
Hz, 1H), 7.37 (dd, J = 8.5, 1.9 Hz, 1H),
6.52 (d, J = 8.5 Hz, 1H), 4.13 (s, 2H). 13C NMR (101 MHz, CDCl3,
ppm): 146.5, 145.8, 137.9, 116.2, 84.8, 78.9.
-
S21
HRMS (CI+): Found: 345.8572 ([M+H] C6H6NI2 Requires: 345.8584).
Spectroscopic data in agreement with
literature.[20]
2,4-Bis(perfluorobutyl)aniline[20]
Perfluorobutyl iodide (9.5 mL, 55 mmol, 1 eq.) was added
dropwise to a well stirred mixture of
2,4-diiodoaniline (10 g, 29 mmol, 1.05 eq.) and bronze (9.4 g,
148 mmol, 5.4 eq.) in DMSO (145
mL) at room temperature. The reaction mixture was then heated at
125 °C for 16 h. The resulting
suspension was concentrated over a stream of nitrogen and the
crude reaction mixture purified by FC (eluent: 10%
EtOAc/hexanes) to afford product (6.46 g, 12.2 mmol, 44%) as a
red liquid. 1H NMR (400 MHz, CDCl3, ppm):
7.51 (d, J = 2.1 Hz, 1H), 7.47 (dd, J = 8.6, 2.1 Hz, 1H), 6.78
(d, J = 8.7 Hz, 1H), 4.61 (s, 2H). 13C NMR (101
MHz, CDCl3, ppm): 148.8, 131.3, 130.8, 128.5, 127.5, 118.0,
117.8, 117.7 (C6), 116.6, 116.5, 113.2, 110.6,
110.3, 110.0. 19F NMR (377 MHz, CDCl3, ppm): -80.9, -81.2 (m),
-108.3, -108.7 (m), -109.2, -109.6 (m), -110.3,
-110.7 (m), -111.0, -111.5 (m), -125.3, -126.0 (m). HRMS (ES-):
Found: 528.0069 ([M-H] C14H4NF18 Requires:
528.0056). Spectroscopic data in agreement with
literature.[20]
2,4-Bis(perfluorobutyl)-1-bromobenzene[20]
2,4-Bis(perfluorobutyl)aniline (98 mg, 0.19 mmol, 1 eq.) in MeCN
(1 mL) was added dropwise
to a stirring mixture of CuBr2 (51 mg, 0.23 mmol, 1.2 eq.) and
tert-butyl nitrite (38 L, 0.28 mmol,
1.5 eq.) in MeCN (2 mL) at 65°C. The resulting dark green
solution was stirred for 24 h before
being quenched with HCl (20% v/w, 1 mL). The crude mixture was
extracted with EtOAc (3 2 mL), dried over
MgSO4 and concentrated in vacuo. The crude product was purified
by FC (eluent: 10% EtOAc/hexanes) to afford
aryl bromide product as a red oil (87 mg, 0.15 mmol, 79%). IR
(film, cm-1): 2964, 2918, 2849, 1610, 1479, 1223,
1198, 1131, 1100, 865, 841, 740, 731. 1H NMR (400 MHz, CDCl3):
7.93 (d, J = 8.4 Hz, 1H), 7.79 (d, J = 2.1
Hz, 1H), 7.62 (dd, J = 8.5, 2.1 Hz, 1H). HRMS (ES+): Found:
591.9145 ([M+H] C14H379BrF18 Requires: 591.9131).
Spectroscopic data in agreement with literature.[20]
2-(2,4-Bis(perfluorobutyl)phenyl)-4,4,5,5-tetramethyl-1,3,2-dioxaborolane
To a solution of 2,4-bis(perfluorobutyl)-1-bromobenzene (2.9 g,
4.9 mmols, 1 eq.) in Et2O
(14.5 mL) at -78 °C was added t-BuLi (1.7 M in pentane, 5.75 mL,
9.8 mmols, 2 eq.). The
solution was then allowed to warm to rt for 5 min before being
cooled to -78 °C and stirred
for a further 30 min. Then, MeOB(pin) (1.54 mL, 9.8 mmols, 2
eq.) was added and the solution was allowed to
warm to rt and stirred for 1.5 h. The reaction mixture was
quenched by addition of sat. NH4Cl (14.5 mL), diluted
with EtOAc (14.5 mL) and washed with brine (7 mL). The phases
were separated and the aqueous phase was
extracted with EtOAc (3 7 mL). The combined organic phases where
dried over MgSO4 and conc. in vacuo. The
crude mixture was purified by FC (eluent: 100% hexanes) to
afford boronic ester product as a colourless oil (2.38
g, 3.7 mmols, 76%). IR (film, cm-1): 2984, 2508, 1350, 1232,
1200, 1134, 1066, 806, 733. 1H NMR (400 MHz,
CDCl3, ppm): 7.83 - 7.72 (m, 3H), 1.38 (s, 12H). 13C NMR (101
MHz, CDCl3, ppm): 134.5, 132.8 (t, J = 24
Hz), 130.6 (t, J = 26 Hz), 129.2, 126.0, 119.0, 118.7, 116.4,
116.2, 116.1, 115.3, 110.3, 110.2, 85.2, 24.7. 19F NMR
(377 MHz, CDCl3, ppm): -81.1 (q, J = 21, 11 Hz), -106.5 (t, J =
15 Hz), -111.8 (t, J = 14 Hz), -120.8 (m), -122.9
(q, J = 22, 11 Hz), -125.6 (m), -125.8 (m). 11B NMR (128 MHz,
CDCl3): 31.1 (s). HRMS (ES+): Found: 657.0889
([M+H] C20H16BO3F18 Requires: 657.0905).
-
S22
2-(2,4-Bis(perfluorobutyl)phenyl)-4-chloropyridine
Pd(PPh3)4 (211 mg, 0.18 mmol, 20 mol%) was added to a two-neck
flask and evacuated and
refilled with N2 (× 3) before adding degassed THF (19 mL).
2-(2,4-bis(perfluorobutyl)phenyl)-
4,4,5,5-tetra-methyl-1,3,2-dioxaborolane (587 mg, 0.92 mmol, 1
eq.) and 2,4-dichloropyridine
(163 mg, 1.1 mmol, 1.2 eq.) were dissolved separately in THF (2
× 5 mL) and added to the
two-neck flask. K2CO3 (317 mg, 2.29 mmol, 2.5 eq.) in H2O (15
mL) was added and the biphasic mixture was
heated at 80 °C for 20 h. The organic phase was evaporated and
the aqueous solution was diluted with EtOAc (75
mL) and H2O (50 mL), the phases were separated and the aqueous
phase was extracted with EtOAc (3 × 50 mL).
The combined organic phase was dried over MgSO4, conc. in vacuo
and the resulting residue purified by FC
(eluent: 5% Et2O/hexanes) to afford biaryl compound product as a
colourless oil (430 mg, 0.69 mmol, 75%). IR
(film, cm-1): 3051, 1574, 1461, 1352, 1229, 1133, 1006, 882,
833, 799, 728. 1H NMR (400 MHz, CDCl3, ppm):
8.56 (dd, J = 4.7, 1.3 Hz, 1H), 7.89 (s, 1H), 7.87 (d, J = 8.1
Hz, 1H), 7.57 (d, J = 8.0 Hz, 1H), 7.38 (m, 2H). 13C
NMR (101 MHz, CDCl3, ppm): 158.3, 149.9, 144.1, 144.0, 132.7,
130.3, 127.5, 124.4, 123.6, 118.9 (t, 33 Hz),
116.4, 116.3, 116.1, 116.0, 115.2 (t, 32 Hz), 113.0, 112.7,
110.3, 109.2. 19F NMR (377 MHz, CDCl3, ppm): -
81.1 (q, J = 19, 10 Hz), -103.9 (t, J = 15 Hz), -111.6 (t, J =
14 Hz), -120.5 (q, J = 21, 11 Hz), -122.7 (q, J = 21, 11
Hz), -125.5, -125.7 (m), -125.8, -126.0 (m). HRMS (ES+): Found:
625.9982 ([M+H] C19H7N35ClF18 Requires:
625.9980).
2-(2-Bromo-4,6-bis(perfluorobutyl)phenyl)-4-chloropyridine
A 5-mL microwave vial was charged with recrystallized NBS (99.7
mg, 0.56 mmol, 2 eq.)
and freshly prepared Pd(PPh3)4 (16 mg, 0.014 mmol, 5 mol%). The
vial was evacuated and
refilled with N2 (× 3) and then a solution of
2-(2,4-bis(perfluorobutyl)phenyl)-4-
chloropyridine (175 mg, 0.28 mmol, 1 eq.) in MeCN (1.4 mL)
added. The yellow mixture was
heated in a microwave at 180 °C for 20 min to afford a brown
solution which was conc. in vacuo and purified by
FC (eluent: 15-30% CH2Cl2/5% PhCH3/hexanes) to afford aryl
bromide product as a yellow oil (33 mg, 0.045
mmol, 16%). IR (film, cm-1): 3063, 1576, 1555, 1352, 1230, 1200,
1133, 1008, 880, 804, 730. 1H NMR (400 MHz,
CDCl3, ppm): 8.61 (d, J = 5.4 Hz, 1H), 8.13 (s, 1H), 7.84 (s,
1H), 7.41 (dd, J = 5.3, 1.9 Hz, 1H), 7.30 (s, 1H).
13C NMR (101 MHz, CDCl3, ppm): 157.1, 150.2, 144.3, 143.7,
135.0, 131.2 (t, J = 24 Hz), 129.8 (t, J = 24 Hz),
127.8, 126.6, 124.8, 124.0, 118.9, 118.6, 116.0, 115.7, 110.5,
110.2, 110.1, 109.2. 19F NMR (377 MHz, CDCl3,
ppm): -81.0 (q, J = 19, 10 Hz), -103.2, -105.5 (m), -111.6 (t, J
= 14), -120.4 (q, J = 24, 12 Hz), -122.4 (q, J = 22,
11 Hz), -125.4, -125.6 (m), -125.8 (q, J = 29, 15 Hz). HRMS
(ES+): Found: 703.9065 ([M+H] C19H6N35ClBrF18
Requires: 703.9085).
2-(2-Bromo-4,6-bis(perfluorobutyl)phenyl)-4-chloropyridine-N-oxide
2-(2-Bromo-4,6-bis(perfluorobutyl)phenyl)-4-chloropyridine (27.5
mg, 0.040 mmol, 1 eq.)
was dissolved in CH2Cl2 (0.3 mL) at 0°C. To the solution was
added H2O (0.1 mL), NaHCO3
(7 mg, 0.080 mmol, 2 eq.) and m-CPBA (11 mg, 0.060 mmol, 1.5
eq.) and the mixture was
allowed to warm to rt. Then a second batch of m-CPBA (4 mg,
0.020 mmol, 0.5 eq.) was added and the mixture
was heated at 40 °C in a sealed tube for 20 h. The resulting
mixture was diluted with CH2Cl2 (1 mL), the phases
were separated and the organic phase was washed with Na2SO4
(sat, 1 mL), NaHCO3 (sat, 1 mL) and brine (1 mL).
The combined aqueous phase was extracted with CH2Cl2 (3 1 mL)
and the organic phases were conc. in vacuo.
-
S23
The crude residue was purified by FC (eluent: 20% EtOAc/hexanes)
to afford N-oxide product as a colourless oil
(26 mg, 0.035 mmol, 88%). IR (film, cm-1): 3079, 1448, 1402,
1352, 1233, 1201, 1135, 1010, 884, 827, 787, 725.
1H NMR (400 MHz, CDCl3, ppm): 8.25 (d, J = 7.0 Hz, 1H), 8.17 (s,
1H), 7.88 (s, 1H), 7.38 (dd, J = 7.1, 2.9 Hz,
1H), 7.23 (t, J = 3.1 Hz, 1H). 13C NMR (101 MHz, CDCl3, ppm):
146.9, 140.5, 136.4, 135.2, 133.1, 132.13 (t, J
= 26 Hz), 130.7 (t, J = 23 Hz), 127.4, 127.2, 126.8, 117.5,
115.9, 115.5, 115.4, 115.1, 114.3, 112.6, 110.4, 110.0.
19F NMR (377 MHz, CDCl3, ppm): -81.0 (q, J = 18, 9 Hz), -101.7,
-101.8 (m), -102.3, -102.6 (m), -111.6, -111.7
(m), 122.2, -122.3 (m), 125.5, -125.7 (m). HRMS (ES+): Found:
721.9005 ([M+H] C19H6NOF1835Cl79Br Requires:
721.9004).
2-(2-Bromo-4,6-bis(perfluorobutyl)phenyl)-4-(dimethylamino)
pyridine-N-oxide
To a solution of
(2-Bromo-4,6-bis(perfluorobutyl)phenyl)-4-chloropyridine-N-oxide
(38
mg, 0.053 mmol, 1 eq.) in MeCN (0.6 mL) in a microwave vial was
added HNMe2 (60% in
H2O, 0.23 mL, 2.63 mmol, 50 eq.). The solution was heated in a
microwave for 135 min at
100 °C and the resulting mixture was conc. in vacuo. The crude
residue was purified by FC
(eluent: 30-50% i-PrOH/EtOAc) to afford desired product as a
yellow oil (17 mg, 0.023 mmol, 44%). IR (film,
cm-1): 2961, 2925, 1636, 1506, 1429, 1352, 1259, 1230, 1095,
1020, 798. 1H NMR (400 MHz, CDCl3): 8.22 –
8.05 (m, 2H), 7.84 (s, 1H), 6.63 (dd, J = 7.5, 3.5 Hz, 1H), 6.36
(t, J = 3.6 Hz, 1H), 3.04 (s, 6H). 13C NMR (101
MHz, CDCl3): 147.5, 145.5, 139.8, 138.6, 135.2, 131.5, 130.5,
126.8, 122.5, 117.1, 116.0, 114.9, 114.2, 110.7,
110.1, 110.0, 109.9, 108.8, 108.5, 39.9. 19F NMR (377 MHz,
CDCl3): -80.9 (t, J = 10 Hz), -111.44, -111.7 (m),
-122.23 (q, J = 10 Hz), -125.4, -125.8 (m). HRMS (ES+): Found:
728.9848 ([M+H] C21H12N2O79BrF18 Requires:
728.9846).
2-(3,5-Bis(perfluorobutyl)-5'-phenyl-[1,1':3',1''-terphenyl]-2-yl)-4-(dimethylamino)pyridine-N-oxide
(4b)
A sealed vial with 5’-m-terphenyl boronic acid (16 mg, 0.058
mmol, 2 eq.), Pd2(dba)3 (2 mg,
0.0021 mmol, 7.5 mol%), SPhos (2 mg, 0.0042 mmol, 0.15 eq.) and
K3PO4 (18 mg, 0.086
mmol, 3 eq.) was evacuated for 1 h and refilled with argon. To
the vial was then added a
solution of
2-(2-bromo-4,6-bis(perfluorobutyl)phenyl)-4-(dimethyl-amino)
pyridine 1-oxide
(21 mg, 0.029 mmol, 1 eq.) in degassed n-butanol (0.2 mL). The
reaction mixture was heated at 90 °C for 72 h
before being conc. in vacuo. The crude residue was purified by
FC (eluent: 10% EtOAc/Hexanes to 80% i-
PrOH/EtOAc) to afford desired as a yellow oil (11 mg, 0.012
mmol, 44%). IR (film, cm-1): 3040, 2923, 2853,
1730, 1634, 1506, 1430, 1350, 1232, 1134, 1094, 1027, 909, 849,
803, 849, 803, 734, 698. 1H NMR (400 MHz,
CDCl3): 8.09 – 7.93 (m, 3H), 7.84 – 7.70 (m), 7.68 – 7.59 (m),
7.52 – 7.43 (m), 7.43 – 7.35 (m), 6.38 (dd, J =
7.5, 3.5 Hz, 1H), 6.18 (t, J = 3.5 Hz, 1H), 2.86 (s, 6H). 13C
NMR (101 MHz, CDCl3): 141.7, 140.3, 139.1, 137.0,
132.4, 129.0, 127.9, 127.2, 126.2, 125.7, 109.4, 108.4, 39.77.
19F NMR (377 MHz, CDCl3): -80.8, -81.0 (m), -
111.2, -111.6 (m), -125.3, -125.8 (m). HRMS (ES+): Found:
879.1714 ([M+H] C39H25N2OF18 Requires:
879.1679).
The racemic catalyst (±)-4b was resolved using preparative SFC
[BzS column (benzene sulphonamide), 21.2 ×
250 mm, 70 mL/min, 100 bar, 20% MeOH (+ 0.2%
dimethylethylamine), 35 °C] and the enantiomers collected.
Analytical conditions: [BzS column (benzene sulphonamide), 4.6 ×
150 mm, 3 mL/min, 150 bar, 5-55% MeOH
(+ 0.2% dimethylethylamine), 40 °C] afforded (-)-4b: Rt = 1.97
min. (+)-4b: Rt = 2.79 min.
-
S24
(+)-4b: Rt = 2.79 min
-
S25
6. Assignment of the absolute configuration of catalyst 4a
enantiomers
All managed data is located in a data repository,[21] assigned a
collection DOI: 10.14469/hpc/1774
Geometry optimisation
Geometry optimisations were performed at the B3LYP
/6-311g(2df,p) level including a Grimme D3 dispersion
correction using Becke-Johnson damping[22] for the (Sa)
configured enantiomer of 4a. The effect of chloroform
solvent was modelled as a continuum (CPCM model). With three
rotatable bonds, eight conformations for the (Sa)
atropisomer were computed and each was verified as a minimum by
vibrational analysis.
Eight conformers were located, with the lowest energy one
(conformer 2) and the highest energy one (conformer
5) differing by 2.39 in G298 (kcal/mol, see Optical Rotation
table, below). The conformers cluster into two
groups: conformers 1-4 have the ter-phenyl and (CF3)2C6H2 rings
~coplanar, whereas conformers 5-8 have the ter-
phenyl and (CF3)2C6H2 rings ~perpendicular. e.g.
Conformer 1 Conformer 5
Optical Rotation (OR) prediction
The experimental OR value for enantiomer (+)-4a (AT1), which
elutes second on the OD-H chiral HPLC column
with Rt = 55.2 min (>99% ee), was measured as: []D27 +49.5 (c
= 0.2, CHCl3).
The OR values for each of the eight conformers of (Sa)-4a, for
the measured wavelength of 589nm as well as at
800, 535.8 and 366nm, were calculated using the
TPSSh/6-311++G(d,p) combination with geometries at the
previously optimized B3LYP+gd3bj/6-311g(2df,p)/SCRF=chloroform
level. The conformers cluster into two
groups: 1-4 have predicted positive OR589 values whereas
conformers 5-8 have negative OR values. Following
Boltzmann weighting, this predicts an overall OR value of []589
+94.2 (CHCl3).
This analysis suggests that enantiomer (+)-4a has the
(Sa)-configuration, but the assignment is critically dependent
on high accuracy for the computed energies used in the Boltzmann
weighting and further corroboration is essential.
Electronic Circular Dichroism (ECD):
The experimental UV and ECD spectra were recorded for both
enantiomers of catalyst 4a. Both enantiomers gave
identical IR spectra as expected and the VCD traces were mirror
images of each other as expected. Enantiomer
(+)-4a has a positive Cotton effect at ~290 nm (blue) whereas
enantiomer (-)-4a has a negative Cotton effect at
this wavelength (red).
conformer E(Hartree) E(kcal/mol) dE(kcal/mol) exp(-E/RT)
population OR (589 nm) weighted OR
1 -2056.114931 -1295352.41 0.3843 0.522538081 0.173125554 48.6
8.4
2 -2056.115541 -1295352.79 0 1 0.331316625 166.5 55.2
3 -2056.115297 -1295352.64 0.15372 0.771342353 0.255558545 61.3
15.7
4 -2056.114419 -1295352.08 0.70686 0.303055285 0.100407254 217.3
21.8
5 -2056.11175 -1295350.4 2.38833 0.017708116 0.005866993 -44.8
-0.3
6 -2056.113168 -1295351.3 1.49499 0.080063137 0.026526248 -58.9
-1.6
7 -2056.112772 -1295351.05 1.74447 0.052533982 0.017405381 -76.8
-1.3
8 -2056.114314 -1295352.02 0.77301 0.2710199 0.089793399 -41.4
-3.7
1 94.2
https://data.hpc.imperial.ac.uk/resolve?doi=1774
-
S26
UV ECD
The ECD spectra for each of the eight conformers of (Sa)-4a were
calculated using time-dependent DFT at the
TPSSh/6-311++G(2df,p)/SCRF=chloroform level of theory. All the
wavelengths were subsequently corrected by
a +10 nm shift for optimal fit with the experiment. The
conformers cluster into two groups: 1-4 have positive
Cotton effects at ~290 nm whereas conformers 2-8 have negative
Cotton effects at this wavelength. e.g.
Conformer 2 Conformer 7
A Boltzmann averaged ECD curve based on the
B3LYP+D3BJ/6-311g(2df,p) relative free energies (G298) was
then constructed and found to overlay well with the experimental
curve corresponding to (+)-4a.
This analysis also suggests that enantiomer (+)-4a has the
(Sa)-configuration. Again the assignment is critically
dependent on the computed free energies used in the Boltzmann
weighting.
Vibrational Circular Dichroism (VCD):
The experimental IR and VCD spectra were recorded for both
enantiomers of catalyst 4a. Both enantiomers gave
identical IR spectra as expected and the VCD traces were mirror
images of each other as expected: (+)-4a (green)
vs. (-)-4a (red). The strongest peaks are in the region
1000-1250 cm-1.
IR VCD
The VCD spectra for each of the eight conformers of (Sa)-4a were
calculated at the B97XD/Def2-
TZVPP/SCRF=chloroform level, including one explicit chloroform
strongly hydrogen bonded to the N-oxide
oxygen atom. An atomic mass of 2.0 corresponding to CDCl3 was
used to obtain normal mode wavenumbers, to
which a scaling factor of 0.98 was applied to allow comparison
with the experimental data for (+)-4a (AT 1). All
eight conformers displayed similar spectra in the 1000-1250 cm-1
region (see below) with a pattern negative –
positive – negative –positive (going from low to high
wavenumbers) which fits with the experimental spectrum of
(+)-4a. The higher wavenumber region is less well reproduced by
the simulated spectrum. In this region the
weighting factors matter because the conformers have different
spectra.
-
S27
A Boltzmann averaged VCD curve based on the
B3LYP+D3BJ/6-311g(2df,p) relative free energies was then
constructed and found to overlay well with the experimental
curve corresponding to (+)-4a.
This analysis (supported by the OR and ECD results) confirms
that (+)-4a has the (Sa)-configuration, as this
VCD assignment is essentially independent of the computed free
energies used in the Boltzmann weighting.
-
S28
7. N-Sulfonylative KR of (±)-2-Methylindoline (5a) –
Optimisation with catalyst (-)-4a
Entry R
Temp. (oC)
Solvent Base Time (h)
Additive (1 eq.)
Conv (%)[a]
s[b]
1 4-NO2 0 PhCH3 DIPEA 3 - 100 N.D.
2 2-NO2 0 PhCH3 DIPEA 3 - 60 1.3
3 2-NO2 -40 PhCH3 DIPEA 4 - 53 1.4
4 2-NO2 -40 THF DIPEA 3 - 10 1.9
5 2-NO2 -40 CH2Cl2 DIPEA 3 - 100 N.D.
6 2-NO2 -60 PhCH3 DIPEA 3 - 23 1.9
7 2-NO2 -60 PhCH3 DIPEA 3 NBu4Br 46[c] 4.7
8 2-NO2 -78 PhCH3 DIPEA 3 - 15 4.5
9 2-NO2 -78 PhCH3 DIPEA 3 NBu4Br 20 2.6
10 2-i-Pr, 4-NO2 -60 PhCH3 DIPEA 3 - 54 8.9
11 2-i-Pr, 4-NO2 -60 PhCH3 DIPEA 3 NBu4Br 60 7.8
12 2-i-Pr, 4-NO2 -78 PhCH3 DIPEA 2 - 52 13.8
13 2-i-Pr, 4-NO2 -78 THF DIPEA 4 - 65 7.4
14 2-i-Pr, 4-NO2 -78 PhCH3 PMP 2 -
-
S29
8. KR of (±)-indolines 5a-5q – Analytical scale resolutions with
catalyst (-)-4a
General Procedure C – Kinetic resolution
An oven-dried microwave vial was flushed with argon and sealed.
Using syringes, DIPEA (50 L, 0.3 M solution
in toluene, 1 eq.), (±)-indoline (50 L, 0.3 M solution in
toluene, 1 eq.), appropriate enantiomer of catalyst 4a (339
L, 4.4 mM solution in toluene, 10 mol%) and dry toluene (10 L)
were added. The vial was then cooled to -78
°C. Separately, a solution of 2-isopropyl-4-nitrosulfonyl
chloride (150 L, 0.1 M in toluene, 1 eq.) was frozen in
N2 (l). Immediately upon melting, the solution was transferred
to the microwave vial at -78 °C and stirred for
several hours. The reaction was quenched with a solution of
propylamine (100 L, 1.5 M in toluene, 10 eq.) which
was frozen in liquid N2 and added to the reaction mixture
immediately upon melting the solution. After stirring
for 20 min, the mixture was taken up in a syringe and analysed
by HPLC.
(R)-2-Methylindoline (5a) and
(S)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2-methylindoline (6a)
using
catalyst (-)-4a (Table 1, Entry 7 and Table 2, Entry 1).
Following General Procedure C, (±)-2-methylindoline (5a, 2.0 mg,
0.015 mmol) was resolved for 3 h using
catalyst (-)-4a. The ee of the starting material and the product
were determined by HPLC using a Daicel Chiralpak
OD-H column (eluent: 1% i-PrOH:hexanes; flow rate 0.7
mL/min).
Retention times of starting material 5a: 18.3 min (Major) and
21.9 min (Minor). 76.3% ee. Major
enantiomer assigned as (+)-(R)-5a by comparison of elution times
and optical rotation with literature
values.[23–25]
Retention times of product 6a: 23.7 min (Major) and 27.6 min
(Minor). 71.8% ee.
Conversion = 51%; selectivity = 13.8.
HPLC analysis of crude reaction mixture after quench:
-
S30
HPLC analysis of starting material 5a:
(S)-2-Methylindoline (5a) and
(R)-1-((2-Isopropyl-4-nitrophenyl)sulfonyl)-2-methylindoline (6a)
using
catalyst (+)-4b (Table 1, Entry 9).
Following General Procedure C, (±)-2-methylindoline (5a, 2.0 mg,
0.015 mmol) was resolved for 24 h using
catalyst (+)-4b. The ee of the starting material and the product
were determined by HPLC using a Daicel Chiralpak
OD-H column (eluent: 1% i-PrOH:hexanes; flow rate 0.7
mL/min).
Retention times of starting material 5a: 10.4 min (Minor) and
12.0 min (Major).* 79.3% ee. Major
enantiomer assigned as (-)-(S)-5a by comparison of elution times
and optical rotation with literature
values.[23–25]
Retention times of product 6a: 13.2 min (Minor) and 14.1 min
(Major). 82.1% ee.
Conversion = 48%; selectivity = 8.2.
HPLC analysis of crude reaction mixture after quench:
* NB. The HPLC retention times for starting material 5a and
product 6a in this analysis were significantly shorter than for
the
same compounds previously under the same elution conditions
(when using the (-)-4b catalyst), but the identity of the
products was confirmed by co-injected with authentic standards
and by 1H NMR.
-
S31
(R)-2-(((Triethylsilyl)oxy)methyl)indoline (5b) and
(S)-1-((2-isopropyl-4-nitrophenyl)sulfonyl)-2-
(((triethylsilyl)oxy)methyl)indoline (6b) using catalyst (+)-4a
(Table 2, Entry 2).
Following General Procedure C,
(±)-2-(((triethylsilyl)oxy)methyl)indoline (5b, 2.2 mg, 0.015 mmol)
was
resolved for 6 h using catalyst (+)-4a. The ee of the starting
material and the product were determined by HPLC
using a Daicel Chiralpak IA column (eluent: 1% i-PrOH:hexanes;
flow rate 0.7 mL/min).
Retention times of starting material 5b: 4.5 min (Major) and 4.4
min (Minor). 68.5% ee. Major
enantiomer assumed to be of (R) configuration by analogy with
5d.
Retention times of product 6b: 12.5 min (Major) and 14.1 min
(Minor). 91.1% ee
Conversion = 34%; selectivity = 14.8.
HPLC analysis of crude reaction mixture after quench:
-
S32
HPLC analysis of racemic starting material:
(S)-2-(((Triisopropylsilyl)oxy)methyl)indoline (5c) and
(R)-1-((2-isopropyl-4-nitrophenyl)sulfonyl)-2-
(((triisopropylsilyl)oxy)methyl)indoline (6c) using catalyst
(-)-4a (Table 2, Entry 3).
Following General procedure C,
(±)-2-(((triisopropylsilyl)oxy)methyl)indoline (5c, 4.6 mg, 0.015
mmol) was
resolved for 5 h using catalyst (-)-4a. The ee of the product
was determined by HPLC using a Daicel Chiralpak IC
column (eluent: 1% i-PrOH:hexanes; flow rate 1.0 mL/min).
Retention times of starting material 5c: 4.5 min (Major) and 4.8
(Minor); poorly resolved. Major
enantiomer assumed to be of (S) configuration by analogy with
5d.
Retention times of product 6c: 9.7 min (Minor) and 13.0 min
(Major). 87.9% ee.
Conversion = 33% [determined by 1H-NMR - comparison of peaks at
H 8.11 ppm (6c) and H 6.41 ppm
(5c)]; selectivity = 10.1.
HPLC analysis of crude reaction mixture after quench:
-
S33
HPLC analysis of racemic product:
(S)-2-(((tert-Butyldimethylsilyl)oxy)methyl)indoline (5d) and
(R)-2-(((tert-butyldimethylsilyl)oxy)methyl)-1-
((2-ethyl-4-nitrophenyl)sulfonyl)indoline (6d) using catalyst
(-)-4a (Table 2, Entry 4).
Following General Procedure C,
(±)-2-(((tert-butyldimethylsilyl)oxy)methyl)indoline (5d, 3.9 mg,
0.015 mmol)
was resolved for 5 h using catalyst (-)-4a. The ee of the
product was determined by HPLC using a Daicel Chiralpak
IC column (eluent: 1% i-PrOH:hexanes; flow rate 1.0 mL/min).
Retention times of starting material 5d: 4.6 min (Major) and 5.1
(Minor); poorly resolved. Major
enantiomer assigned as (+)-(S)-5d by comparison of elution times
and optical rotation with literature
values.[3]
Retention times of product 6d: 10.2 min (Minor) and 12.8 min
(Major). 89.2% ee.
Conversion = 47% [determined by 1H-NMR - comparison of peaks at
H 7.74 ppm (6d) and H 6.39 ppm
(5d)]; selectivity = 17.2.
HPLC analysis of crude reaction mixture after quench:
-
S34
HPLC analysis of racemic product:
(R)-2-Isopropylindoline (5e) and
(S)-2-isopropyl-1-((2-isopropyl-4-nitrophenyl)sulfonyl)indoline
(6e) using
catalyst (+)-4a (Table 2, Entry 5).
Following General Procedure C, (±)-2-isopropylindoline (5e, 2.4
mg, 0.015 mmol) was resolved for 6 h using
catalyst (+)-4a. The ee of the starting material and product was
determined by HPLC using a Daicel Chiralpak IC
column (eluent: 1% i-PrOH:hexanes; flow rate 1.0 mL/min).
Retention times of starting material 5e: 8.2 min (Major) and
13.4 min (Minor). 76.7% ee. Major
enantiomer assigned as (+)-(R)-5a by comparison of elution times
with literature values.[4]
Retention times of product 6e: 14.3 min (Major) and 18.2 min
(Minor). 90.5% ee.
Conversion = 40%; selectivity = 16.2.
HPLC analysis of crude reaction mixture after quench: