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Tricyclic Azaergoline Analogues: Synthesis, Structural
Modifications,and Pharmacological Studies
a) Institut fUr Phannazie und Lebensmittelchemie der
Universitiit Miinchen, Sophienstra6e 10, SOOO Miinchen 2,
Germany
b) Abteilung Biochemie, Boehringer Ingelheim KG, 6507
IngelheimlRhein, Germany
As an extension of previous investigations on synthesis and
dopamineautoreceptor activity of bicyclic ergoline analogues the
tricyclic azaergolineanalogues 9a and 9b were synthesized.
Funhermore, the geometry of thearomatic ~-ethylamine moiety of 9a,b
was modified by stereoselective con-struction of the cycloheptenyl
fused pyrazolopyridine derivative 7 and theaminomethyl substituted
tricycle 10. Binding affinity of these compounds atdopamine (OA)
receptor sites was investigated employing rat striatum ho-mogenate:
The compounds reveal modest to wealc, but selective binding to
adopamine 0-2 receptor when it is labelled with the OA-autoreceptor
agonist[3HI-SNO 919. In vivo studies with mice showed that 7, 9a,b,
and 10 affecttheir CNS activity.
Tricyclische Azaergolin Analoge: Synthese, strukturelle
Modifikationenund pharmakologische Studien
1m AnschluB an friihere Untersuchungen zur Synthese und Oopamin
Autore-zeptor Aktivitiit bicyclischer Ergolin Analoger, wurden die
tricyclischenAzaergolin Analogen 9a und 9b synthetisiert. AuBerdem
sollte die Geome-trie der aromatisch substituierten
~-Ethylamin-Struktur vaniert werden. Eswurde deshalb das
Cycloheptenylamin Derivat 7 und der aminomethyl-sub-stituierte
Tricyclus 10 dargestellt. Die Affinitat dieser Verbindungen zu
denOopamin (OA) Rezeptor Bindungsstellen wurde untersucht, wobei
das Stria-tum der Ratte verwendet wurde. Die Verbindungen binden
mittelstark bisschwach an den mit dem OA-Autorezeptor Agonisten
eHI-SND 919 mar-kienen 0-2 Rezeptor. In vivo Untersuchungen mit
Mausen zeigten, daB 7,9a,b und 10 die ZNS Aktivitiit der Tiere
beeinflussen.
Since the fortuitous discovery of chlorpromazine!) a large
number ofneuroleptics have been developed2). It is postulated that
the antipsychoticactivity of the classical neuroleptics is due to a
blocking effect at thepostsynaptic 0-2 receptors3). Since these 0-2
receptor antagonists induceextrapyramidal side effects (i.e.,
pseudo-parkinsonism), alternative ap-proaches for preventing the
symptoms of schizophrenia attract considerableattention in recent
years 4). One of these novel approaches is to employselective
OA-autoreceptor agonists, which decrease synthesis and releaseof
dopamine (OA)5,6). Thus the hyperactivity in the meso limbic
dopaminer-gic system (A 10 system) of schizophrenia patients should
be reduced.Since it is assumed that the binding sites of the
postsynaptic 0-2 receptorand its prejunctional congener are very
similar5), it seemed to be a valuablestrategy to modify the
molecular structure of known postsynaptic 0-2agonists, in order to
develop OA autoreceptor agonists.
In fact, we and others have shown that this is possible,
byapplying the DA active bicyclic ergoline analogue 1 as amodel
compound. Structural modifications at the aromaticregion resulted
in selective autoreceptor activity of the deri-vatives 27), 3 (SND
919)8), and 4, 59).
As an extension of our work, we try to evaluate specificligands
for the DA autoreceptor by structural changes ofthe tricyclic
ergoline analogue 6, which is also known toexhibit DA agonistic
activitylO). Thus, we are investigatingaza analogues with
pyrazolo[1,5-a]pyridine (8)11) or tetra-hydropyrazolo[ I ,5-0
]pyridine substructure (9). In thispaper, we report on syntheses
and phannacological studiesof both diastereomers of the
hexahydropyrazoloquinolinederivative 9. As a further modification,
the geometry of thearomatic ethyl amine moiety of 9 was varied by
construc-tion of the tetrahydropyrazolopyridyl fused
cyclohepteny-lamine 7 and the aminomethyl substituted pyran
derivative10.
c5:N-N
\H
NPr2 /'
~
~8
.::::::?
-
The synthesis of the target compounds 9a and 9b wasplanned by a
stereospecific Clirtius rearrangement startingfrom the carboxylates
14a and 14b, which we obtained fromthe pyrazolopyridine carboxylate
11 via the ~-ketoester 12aand the iodide 13 as the key
intermediatesl2). The hydrolysisof the esters 14a and 14b was
performed by NaOH in diox-ane/H20 to yield the carboxylic acids ISa
and ISb, respec-tively, both as pure diastereomers. Treatment of
ISa,b withdiphenyl phosphorazidate (DPPA) in acetonitrile I3.14),
fol-lowed by acidic hydrolysis of the intermediately formed
iso-cyanates, afforded the primary amines 16a and 16b withcomplete
retention of configuration, indicated by NMRspectroscopy. This
reaction is best monitored by IR-spec-troscopy by observing the
appearence/disappearence of thediagnostic bands at 2260 (N=C=O) and
1710 em'! (O=C-OH). FinaIly the primary amines 16a and 16b were
trans-formed into the dipropylamines 9a and 9b by use of pro-pionic
aldehyde and NaCNBH3. For both products the cy-clohexenyl ring
adopts a half-chair conformation, when theamine substituent is
positionated axiaIly for 9a and equator-ially for 9b, according to
the NMR data.
dOOC'H'~11
H~~)~:00
12a: n = 112b:n=2
/ ~
&;H'17: X =OH18: X=OMes19:X= I
~
biRR'H ~N~N20a: R = COZCH3.; R' = H20b: R = H; R' = c;02CH3
21: R = C02H; R' = H22: R = NH2; R' = H
7: R = NPr2; R' = H
14a: R = C02~H3.; R' = H14b. R = H, R = C02CH315a: R = C02H; R'
= H15b: R = H: R' = C02H16a: R = NH2: R' = H16b: R = H; R' = NH29a:
R = NPr2; R' = H9b: R = H; R' = NPr2
For the synthesis of the homologues cycloheptene
fusedheterocycles the hydroxyethyl substituted ~-ketoester
12b,which can be efficiently derived from 11, according to
pre-vious studiesI5), should serve as a suitable educt. Reductionof
the aromatic ketone 12b was achieved by catalytic hy-drogenation
(Pd/C) at 60 bar pressure and l30°C to give 17
in 92% yield. Subsequently the primary alcohol 17 was con-verted
into the mesylate 18. Treatment of 18 with NaIyielded the
electrophile 19, which could be cyclized by a7-(enolexo)-exo-tet
ring closure using LDA as a base, at-78°e. Surprisingly, the ring
closure proceeds stereoselec-tively to afford the trans
diastereomer 20a exclusively, Bycontrast, the 6-(enolexo)-exo-tet
cyclization of 13 affords14a and 14b in a I: I ratio12). We reason
that the cyclohep-tene derivative 20a is formed selectively because
- kineti-caIly controlled - the reaction proceeds through a chair
typetransition state, leading to the trans configurated
product(Figure I). On the other hand, formation of the
6-memberedring requires much higher temp. (O°C). Thus, under
thestrongly basic conditions epimerization takes place and
athermodynamicaIly controlled mixture of 14a and 14b isproduced.
Such an equilibration can be also observed forthe 7-membered case,
by treating 20a with LDA at O°C,when a I: I mixture of
diastereomers (20a and 20b) wasisolated.
Our final product 7 was synthesized from 20a in 53%yield by
hydrolysis, followed by Curtius rearrangement andreductive
alkylation via the intermediates 21 and 22.
x) 0rtCH3
C)~,"12a: X = OH; R = H12c: X = I; R = H12d: X = OH; R = CH3
X=y ~OH(yrCH'~e'H[~~:H'
~ ~~ ..
23 24a; R = H" 24b: R = CH3
'" NOE /,.- H R' .¥
\OE( \ 0i+RH' ••~~A R
65a~, /)N.~25a: R = H; R' = COj!CH;)25b; R = CHJ: R' =
c;02CH325c. R = H, R = C02H25d: R = H; R' = NH2
10: R = H; R' = NPr2
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Previously, we have demonstrated that anionic cyclizationof the
iodide 12c results in O-alkylation to give the enolether 23
eXclusively'S). We regarded this compound as auseful precursor for
the synthesis of the amine 10, whichwas planned to be investigated
as a potential DA equivalentwith a differently locked ethyl amine
conformation. Ac-tually, catalytic hydrogenation (Pd/C) of the enol
ether 23afforded the pseudo-equatorially substituted pyran
deriva-tive 2Sa selectively. The nucleophilic approach from
thepseudo-axial side might be explained by transition state
sta-bilization due to interaction of the axially positioned
oxygenlone-pair and the incipient low lying vacant CH-orbital0"*"
16). In case of an equatorial approach, torsional strainbetween the
axial 0 lone-pair and the incipient 0"" CH-orbi-tal would
destabilize the transition structure'?) (Fig. 2).
The structure of 25a was elucidated by IH-NMR spectroscopy
observinga significant dipolar exchange of magnetism between H-5 ••
and H-3, due to1,3-diaxial interference. The position of H-5ax was
determined by the H,H-COSY technique, a diagnostic vicinal coupling
constant (\ax'5a = 10.7Hz), and a significant NOE with H-6ax
(1,3-diaxial interaction).
The conversion of the ester 2Sa into the target compound10 was
performed by Curtius rearrangement through theintermediates 2Sc and
2Sd, as described for the syntheses of7 and 9.
Alternatively, 2Sa can be synthesized directly from theprimary
alcohol 12at2) - a synthetic precursor of 12c and 23- by catalytic
hydrogenation in acetic acid in 64% yield.This is an essential
improvement of the synthesis since thepathway via 12c and 23
requires 3 additional steps and af-fords an overall yield of only
15%. We expect, that thereaction proceeds through the hemiacetal
24a. Then, 24acan either eliminate H20 to give 23 which is
subsequentlyhydrogenated, or hydrogenation takes place on an
inter-mediately formed stabilized carbenium ion. To
investigatewhether the formation of an enolether by dehydration
isessential for this one pot procedure the dimethyl
substitutedanalogue 12d was heated using similar conditions
(HOAc,140°C, 50 bar H2, Pd/C). In fact, the reaction works
verysmoothly to give 2Sb as a single diastereomer, although -due to
the quaternary C-atom - dehydration of the hemiace-tal 24b is
impossible.
The educt 12d was prepared from the aromatic ester 2612)by ester
condensation to give the p-keto ester 27. Afterdeprotonation by LDA
27 was reacted with benzyloxy-methyl chloride to afford 12e, which
could be debenzylatedby hydrogenolysis to yield 12d.
Employing rat striatal membranes, the novel tricyclicazaergoline
analogues 7, 9a,b, and 10 were evaluated fortheir binding affinity
to the dopamine D-l receptor labelledwith eHl-SCH 23390 and to the
D-2 receptor sites labelledwith eH]-spiroperidol and eH]-SND 919, a
compoundwhich in functional in vivo experiments pointed out to be
anautoreceptor agonisfl). It turned out, that there exists a
signifi-cant affinity to the DA receptor site labelled with
eH]-SND919, which is selective since an affinity to the
postsynapticD-l and to the D-2 receptor labelled with
eH]-spiroperidolcould not be observed. However, the ICso values
demonstratethe ability of 7, 9a,b, and 10 to displace eH]-SND 919
isonly modest (Table 1). The most active compound was
theequatorially substituted cis isomer 9b, which gave an ICsovalue
of 4.4 flM. (By contrast, our previously developed bi-cyclic
ergoline analogue (S)-3 showed a 147-fold higher af-finity (ICso =
0.03 flM)9». The trans configuration of the cy-cloheptene fused
homologue 7 resulted only in a slight loss ofaffinity (ICso = 6.3
flM), when compared to 9b. This is easyto understand because the
dipropylamino group of 7 is alsoequatorially orientated. On the
other hand, the cyclohexeny-lamine fused trans diastereomer 9a with
an axially posi-tioned dipropylamino group had a 4.3 fold lower
affinity than9b. The lowest ICso value (23 flM) was measured for
thepyran derivative 10, when also a conformational change ofthe
ethylamine moiety resulted in a decrease of the affinity tothe
DA-receptorlabelled with eH]-SND 919.
ICso [11M]
compd 0-1' , D-2b DA-autoreceptor c
7 > 100 > 100 6.39a > 100 > 100 199b > 100 >
100 4.410 > 100 > 100 23
In accordance to the receptor binding data, 9b and 7turned out
to be the most active compounds in vivo. Ourbehavioural-activity
screening with mice showed that all thetest compounds (7, 9a,b, and
10) caused excitation includ-ing Straub tail, vocalization and
convulsion, immediatelyafter injection. After this period of
excitation both cyclo-
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Table 2: Locomotor Activity Measurements (0-60 min)
compound counts (x ± S.E.M.) control counts C (it ± S.E.M.) t1d
P7 (25mg) 3046±532 1992±275 +53%
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was filtered (CeliteR AFA) and the filtrate was evaporated. The
residue waspurified by flash chromatography (CH2Cl2 - CH30H 97:3)
to give 130 mg(86%) ofl2d as a colorless oil.- CI4H2oN204 (280.3)
Calcd. C 60.0 H 7.19 N10.0 Found C 60.0 H 7.16 N 10.0; mol.-mass
280 (ms).- IR (NaCI): 3390;2950; 1740; 1660 cm·l._ IH-NMR (CDeI3):
() (ppm) = 1.48 (s, 3H, CCH3),1049 (s, 3H, CCH3), 1.78-2.20 (m, 4H,
H2C-5, H2C-6), 2.60 (br-s, IH, OH),3.64-3.66 (m, 2H, CH20), 3.68
(s, 3H, OCH3), 3.85-3.86 (m, IH. HC-4),4.00 (m, I H, H•• C-7), 4.27
(m, I H, HeqC-7), 7.22 (s, 1H, HC-2).
Methyl (±}-3-(4-benzyloxymethyl-4,5
.6,7-tetrahydropyrazolo[1,5-a]pyridill-3-yl)2,2-dimethyl-3-oxo-propionate
(Ue)
To a solution of 27 (250 mg, 1 mmol) in 10 ml of THF were
addeddropwise 3 ml of freshly prepared LDA (0.32 molar in THF) at
_78°C. Thereaction mixture was stirred at this temp. for 30 min,
when it was addeddropwise to a precooled solution (-78°C) of
benzyloxymethylchloride(BOM-CI; 234 mg, 1.5 mmol) in 10 ml ofTHF.
After 30 min it was addedto a mixture of ether and satd. aqueous
solution of NaHC03. The org. layerwas dried (MgS04) and evaporated
and the residue was separated by flashchromatography (petroleum
ether - EtOAc 1:1) to give 250 mg (68%) ofpure 12e as a colorless
solid; m.p. 83°C.- C21H26N204 (370.5) Calcd. C68.1 H 7.07 N 7.6
Found C 67.9 H 7.10 N 7.7; mol.-mass 370 (ms).- IR(KBr): 3040;
2950; 2870; 1740; 1660 cm-I.-IH-NMR (CDCI3): 0 (ppm) =1.46 (s, 3H,
CCH3), 1.47 (s, 3H, CCH3), 1.73-2.29 (m, 4H, H2C-5, H2C-6),3.55
(dd, J = 9.5, 8.8 Hz, 1H, PhCH20C.!h), 3.65 (s, 3H, OCH3), 3.74
(dd,J = 9.5,3.0 Hz, tH, PhCH20Cl:!.l), 3.83-3.85 (m, IH. HC-4).
3.96 (ddd. J =13.2, 11.7, 5.1 Hz, IH, H••C-7), 4.21 (br-dd, J =
13.2, 3.6 Hz, IH, HeqC-7),4046 (d, J = 11.7 Hz, IH, PhCH2), 4.66
(d, J = 11.7 Hz, 1H, PhCH2),7.25-7.36 (m, 5H, Ph), 7.69 (s, IH,
HC-2).
(4RS ,5aRS}-4,5 ,Sa ,6 ,7 ,8-Hexahydro-3 H-pyrazolo[2,3 ,4-j,i]
quinolin-4-yl-carboxylic acid (ISa)
A solution of 14a (82 mg, 0.37 mmol) in 2 ml of dioxane and 1.5
ml of NNaOH was stirred at room temp. for I h. Then the solution
was extractedwith ether. The aqueous layer was acidified to pH =
3-4 with 2 N HCl andsubsequently extracted with CH2CI2 - CH30H 9:1.
The org. layer gave 50mg (66%) of ISa as a colorless solid, m.p.
191°C, after drying (MgS04),evaporation, and flash chromatography
(CH2CI2 - CH30H 9:1).-CIlH14N202 (206.3) Calcd. C 64.1 H 6.84 N
13.6 Found C 64.2 H 7.07 N13.2; mol.-mass 206 (ms).- IR (KBr):
3430; 2930; 2850; 1700 cm·I.- IH_NMR (CDCI3): () (ppm) = 1.20
(br-q, J = 12 Hz, IH, H••C-6), 1.45 (ddd, J= 12.5, 12.5,8 Hz, IH,
H••C-5), 2.01-2.15 (m, 3H, HeqC-6, H2C-7), 2042(br-d, J = 13 Hz,
IH, HeqC-5), 2.67 (dd, J = 16.2,6.6 Hz, IH, H••C-3), 2.78(m, IH,
Ha.C-5a), 3.09 (m, IH, HeqC-4), 3.15 (d, J = 16.2 Hz, IH,
HeqC-3),3.85-3.90 (m, 1H, Ha.C-8), 4.26-4.30 (m, IH, HeqC-8), 7.31
(s, 1H. HC-2).
(4RS ,5aSR)-4 ,5 ,5a.6 ,7,8-hexahydro- 3H-pyrazolo[2,3
,4-j,i]quinolill-4-yl-carboxylic acid (ISb)
A solution of 14b (70 mg, 0.32 mmol) in 2 ml of dioxane and 1.5
ml of NNaOH was stirred at room temp. for I h and worked up as
described for ISato give 45 mg (68%) of ISb as a colorless solid;
m.p. 209°C.- CII H 14N202(206.3) Calcd. C 64.1 H 6.84 N 13.6 Found
C 64.2 H 6.99 N 1304; mol.-mass206 (ms).- IR (KBr): 3430; 2950;
2850; 1710 cm-I.- IH-NMR (CDCI3): ()(ppm) = 1.20 (br-q, J = 13 Hz,
IH, Ha.C-6), 1.46 (q, J = 12.5 Hz. IH. HaxC-5),2.01-2.22 (m. 3H,
HeqC-6. H2C-7), 2.33 (ddd, J = 12.5,404,2.2 Hz. IH.HeqC-5),
2.68-2.78 (m, 2H, H••C-3. H••C-5a), 2.81-2.89 (m, IH. H••C-4),2.98
(dd, J = 14.7.5.8 Hz, IH, HeqC-3), 3.88 (ddd, J = 12.5, 12.5,5.5
Hz. IH,H••C-8), 4.30 (dd, J = 12.5,5.9 Hz, IH, HeqC-8), 7.33 (s,
IH, HC-2).
(4RS ,SaRS )-4-Amino-4.5 'sa,6,7,8-hexahydro-3
H-pyrazolo[2,3,4-j.i]quinoline (16a)
A mixture of ISa (50 mg. 0.24 mmol). diphenyl phosphorazidate
(67 mg,0.24 mmol) and triethylamine (24 mg, 0.24 mmol) in 15 ml of
acetonitrile
was stirred at 60°C for 5 h. After the addition of 0.5 N HCI (3
ml) thereaction mixture was stirred at room temp. for 1.5 h. The
solution wasconcentrated, then extracted with ether, basified with
2 N NaOH and sub-sequently extracted with CH2CI2. The org. layer
was dried (MgS04) andevaporated to give 28 mg (65%) of 16a as a
colorless oil.- ClOH15N3(177.3) mol.-mass 177 (ms).- IR (NaCl):
3340; 2920; 2850 cm·l._ IH-NMR(CDCI3): 0 (ppm) = 1.25 (dddd. J =
12.5, 12.5, 12.1, 3 Hz, IH. Hax C-6),1.37 (ddd, J = 12.5, 12.1,2.6
Hz, IH, H••C-5), 1.95-2.01 (m. 2H. HeqC-5,HeqC-6), 2.05-2.23 (m.
2H. H2C-7), 2047 (d. J = 16.1 Hz. IH. HeqC-3), 2.80(ddd, J =
16.1,5.2,1.8 Hz, IH. H••C-3), 2.91 (dddd. J = 12.1. 11.7.5.5.5.5Hz,
IH, H.xC-5a), 3.60 (br-s, IH, HeqC-4), 3.88 (ddd. J = 12.5.
12.1,5.9Hz, IH, H••C-8), 4.28 (dd, J = 12.5, 6 Hz, IH, HeqC-8),
7.24 (s, IH,HC-2).- Elemental analysis was performed after
conversion of 16a into itsdibenzoyl hydrogen tartrate using I
equiv. of (L)-dibenzoyltartaric acid inether.- C2sH29N30S (535.6)
Calcd. C 62.8 H 5046 N 7.8 Found C 62.9 H5047 N 7.8.
(4RS'saSR)-4-amino-4,5 ,Sa.6.7.8-hexahydro-3H -pyrazolo[2 ,3
,4-j.i]quinoline (16b)
A mixture of ISb (43 mg. 0.21 mmol). diphenyl phosphorazidate
(58mg, 0.21 mmol) and triethylamine (21 mg, 0.21 mmol) in 15 ml of
ace-tonitrile was stirred at 60°C for 5 h. After the addition of
0.5 N HCl (3ml) the reaction mixture was stirred at room temp. for
2.5 h and workedup as described for 16a to give 24 mg (65%) of 16b
as a colorless oil.-ClOH15N3 (177.3) mol.-mass 177 (ms).- IR
(NaCl): 3340: 2920: 2850 em'1._ IH-NMR (CDCI3): () (ppm) = 1.23
(dddd, J = 13.0, 12.5, 12.5.2.8 Hz,IH, H••C-6), 1.27 (ddd, J =
11.8, 11.7, 11.6 Hz, IH, H••C-5). 1.97-2.04(m, 2H, HeqC-5. HeqC-6),
2.05-2.10 (m. IH. Ha.C-7), 2.14-2.20 (m. I H,HeqC-7). 2.19 (ddd, J
= 15.0: 10: 2 Hz, IH. HaxC-3). 2.74 (dddd. J = 12.5.11.8, 5.5, 4
Hz, I H, Ha,C-5a), 2.92 (dd, J = 15.0, 5.9 Hz, IH, HeqC-3),3.26
(dddd, J = 11.6, 1004,5.8.2.9 Hz, IH, H••C-4), 3.85 (ddd. J =
12.5,12.5.5.9 Hz, 1H, H.,C-8), 4.26 (dd. J = 12.5.5.5 Hz. IH.
HeqC-8), 7.27(s, IH, HC-2).
Methyl(±)-3 -[4.5.6.7 ·tetrahydro-4-(2
-hydroxyethyl)-pyrazolo[1,5-a]pyrid-3-yl]propiollate (17)
A mixture ofl2b (1900 mg. 7.14 mmol) and I g of Pd/C (10%) in 60
mlof methanol was stirred at 1300C for 3 h under H2 of 60 bar. Then
it wasfiltered (CeliteR AFA) and the filtrate was evaporated to
give 1650 mg(92%) of 17. Flash chromatography (CH2CI2-CH30H 97:3)
gave an analyti-cally pure sample as a colorless oil.- C13H20N203
(252.3) Calcd. C 61.9 H7.99 N 11.1 Found C 61.7 H 8.18 N 11.1:
mol.-mass 252 (ms).-IR (NaCI):3340; 2950: 2860; 1740 cm-I.- IH-NMR
(CDCI3): () (ppm) = 1.71-2.13 (m,6H, H2C-5, H2C-6, CH2CH20).
2.57-2.60. 2.74-2.79 (2m. 4H.CH2CH2CO), 3.18-3.23 (m. IH, HC-4),
3.68 (s. 3H. OCH3), 3.72-3.77 (m,2H, CH20), 3.98 (ddd, J =
12.5,9.5,5.1 Hz, IH, H••C-7), 4.19 (ddd, J =12.5,5.1,404 Hz, IH,
HeqC-7), 7.28 (s, IH, HC-2).
Methyl(±}-3 -[4,5.6.7 ·tetrahydro-4-(2 -mesyloxyethyl
}-pyrazolo[l,S-a]pyrid-3-yl]propionate (18)
To a solution of 17 (1500 mg. 5.95 mmol) in 100 ml of THF was
addedtriethylamine (0.55 ml, 7 mmol) and methanesulfonyl chloride
(0.97 ml. 7mmol). After stirring at room temp. for 2 h the mixture
was evaporated andthe residue purified by flash chromatography
(CH2ClrCH30H 94:6) toafford 1890 mg (96%) of 18 as a colorless
oil.- CI4H22N20SS (33004)Calcd. C 50.9 H 6.71 N 8.5 Found C 50.6 H
6.63 N 804: mol.-mass 330(ms).- IR (NaCI): 2950: 1740: 1350: 1170
cm·'.- IH-NMR (CDCI.,): ()(ppm) = 1.82-2.16 (m, 6H. H2C-5. H2C-6.
Cl:bCH20), 2.55-2.61. 2.70-2.75(2m, 4H, CH2CH2CO), 3.06 (s. 3H.
OS02CH.,), 3.17-3.21 (m. IH. HC-4),3.68 (s. 3H. OCH3). 3.96-4.04
(m. IH. H".C-7l. 4.17-4.22 (m. IH. HeqC-7).
-
4.30-4.35 (m, 2H, CHzO), 7.30 (s, IH, HC-2).
Methyl (±)-3-f45,6,7 -tetrahydro-4-(2 -iodoethyl )-pyrazolo[J
,5-a]pyrid-3-yl] propionate (19)
A mixture of 18 (1700 mg, 5.15 mmol) and NaI (7700 mg, 51.3
mmol)was stirred in 100 ml of boiling acetone for 4 h. After
cooling to roomtemp. the solvent was removed and the residue
extracted with ether. Theextract was evaporated and the residue
purified by flash chromatography(petroleum ether - EtOAc 4:6) to
give 1230 mg (66%) of 19 as a colorlessoil.- Ct3Ht9INzOz (362.2)
Calcd. C 43.1 H 5.29 N 7.7 Found C 43.0 H 5.45N 7.7; mol.-mass 362
(ms).- IR (NaCI): 2950; 2850; 1740 cm-t._ tH-NMR(CDCI3): /) (ppm) =
1.75-2.24 (m, 6H, HzC-5, HzC-6, CHzCHzI), 2.57-2.61, 2.74-2.78 (2m,
4H, CHzCHzCO), 3.12-3.20 (m, 2H, HC-4, CHzI),3.32 (ddd, J =
12.5,7.3,4.4 Hz, IH, CHzI), 3.69 (s, 3H, OCH3), 4.00 (ddd,J =
12.5,9.6,5.1 Hz, IH, H••C-7), 4.18 (ddd, J = 12.5,5.2,5.1 Hz,
IH,HeqC-7), 7.29 (s, I H, HC-2).
Methyl(5aRS ,8RS)-3,4.5.5a.6 ,7.8 .9-0ctahydl'o-2
.2a-diazabenzo[ c .d]azulene-8-cal'bo:tylate (20a)
Methyl(5aRS ,8SR )-3,4.5 ,5a.6 ,7,8 .9-0ctahydro-2
,2a-diazabenzo[ c ,d]aut/ene-8-cal'bmylate (20b)
To a solution of 19 (362 mg, I mmol) in 30 ml of THF were
addeddropwise 3.4 ml of freshly prepared LDA (0.32 molar in THF) at
_78°e.The reaction mixture was stirred at this temp. for 15min,
when it was addedto a mixture of ether and satd. aqueous solution
of NaHC03. The org. layerwas dried (MgS04) and evaporated and the
residue was separated by flashchromatography (petroleum ether -
EtOAc 1:1) to give 140 mg (60%) ofpure 20a as a colorless solid;
m.p. noc.- Ct3HtsNzOz (234.3) Calcd. C66.6 H 7.74 N 12.0 Found C
66.6 H 7.98 N 11.8; mol.-mass 234 (ms).- IR(KBr): 2930; 2840; 1735
cm-t._ IH-NMR (CDCI3): /) (ppm) = 1.25-1.45(m, 2H, H.,C-5, Ha,C-6),
1.75 (br-q, J = 13 Hz, IH, Ha,C-7), 1.87-1.99 (m,2H, H.,C-4,
H.,C-6), 2.04-2.10 (m, 2H, HeqC-4, HeqC-5), 2.36-2.43 (m,2H,
HeqC-7, HeqC-8), 2.62 (dd, J 0 14.7, 11.8 Hz, IH, Ha,C-9),
2.73-2.78(m, IH, He-5a). 2.97 (ddd, J = 14.7,2.2,2.2 Hz, IH,
HeqC-9), 3.70 (s, 3H,OCH3), 3.94 (ddd, 12.5, 12.5,3.7 Hz, IH,
H.,C-3), 4.22 (dd, J = 12.5,5.1Hz, IH, HeqC-3), 7.23 (s, IH,
HC-I).- 13C_NMR (CDCI3): /) (ppm) = 23.1(HzC-4), 28.8 (H2C-9), 28.9
(HzC-5), 33.8 (HzC-7), 34.3 (HzC-6), 36.5(HC-5a), 45.5 (HC-8), 47.5
(H2C-3), 51.7 (CH3), 115.5 (C-9a), 138.1 (HC-I), 141.0 (C-2b),
176.3 (C02),
Treatment of 20a (23.4 mg, 0.1 mmol) with freshly prepared LDA
(0.3ml, 0.32 molar in THF) in THF (5 ml) at O°C for 30 min gave a
I: I mixtureof 20a and 20b after usual work up.
20b: IH-NMR (CDCI3): /) (ppm) = 1.33-1.43 (m, IH, Ha,C-5),
1.62(br-q, J = 13 Hz, IH, Ha,C-6), 1.74-1.83 (m, IH, HeqC-7),
1.90-2.10 (m,5H, HzC-4, HeqC-5, HeqC-6, HeqC-7), 2.70 (dd, J =
14.7,3 Hz, IH, Ha,C-9),2.70-2.78 (m, IH, Ha,C-5), 2.89 (dddd, J =
6; 6; 3; 3 Hz, IH, HeqC-8),3.05 (dd, J = 14.7,5.9 Hz, IH. HeqC-9),
3.62 (s, 3H. CH3), 3.89-3.97 (m,IH, Ha,C-3), 4.18-4.24 (m, IH,
HeqC-3), 7.24 (s, IH, HC-I).
(5aRS .8RS )-3,4,5 .5a.6 ,7 ,8 ,9-0ctahydro-2 ,2a-diazabenzo[
c.d]azu/ene-8-carboxylic acid (21)
A solution of20a (160 mg, 0.68 mmol) in 10 ml of dioxane and 10
ml ofN NaOH was stirred at room temp. for 2.5 h. Then the solution
was ex-tracted with ether. The aqueous layer was concentrated and
then acidifiedto pH 3-4 with citric acid (10% in H20). After
standing at room temp. for 2h. filtration and drying of the residue
gave 125 mg (83%) of 21 as acolorless solid; m.p. 253°C.-
C12HI6NZ02 (220.3) Calcd. C 65.4 H 7.32 N12.7 Found C 65.8 H 7.23 N
12.5; mol.-mass 220 (ms).- IR (KBr): 3430;2930; 2850; 1710 cm-I._
IH-NMR (CDCl3): /) (ppm) = 1.34 (br-g. J = 13Hz. IH. Ha,C-6), 1.41
(br-g. J = 12 Hz. IH. Ha,C-5), 1.75 (br-g, J = 13 Hz,IH, Ha,C-7),
1.88-2.02 (m, 2H, Ha,C-4, HeqC-6), 2.07-2.13 (m. 2H. HeqC-
4, HeqC-5), 2.30 (It, J = 11.7,2.2 Hz, IH, HaxC-8), 2.39 (ddd. J
= 13; 6.6; 2Hz, IH, HeqC-7), 2.57 (dd, J = 15; 12 Hz, IH, HaxC-9),
2.75-2.81 (m, IH,HC-5a), 2.97 (ddd, J = 14.7,2.2,2.2 Hz, IH,
HeqC-9), 3.90 (ddd, J = 12.5,11.7,3.7 Hz, IH. HaxC-3), 4.13 (dd. J
= 12.5.5.0 Hz. IH, HcqC-3), 7.20 (s,IH, HC-I).- 13C-NMR (CDC!.,):
/) (ppm) = 22.6 (H2C-4), 28.3 (H1C-5,H1C-9), 33.4 (H1C-7), 33.9
(H1C-6), 35.8 (HC-5a), 45.1 (HC-8), 47.1(H1C-3), 115.0 (C-9a),
137.3 (HC-I), 140.5 (C-2b), 176.6 (COz).
(5aRS .8RS)-8-Amino-3.4.5.5a .6.7.8 .9-octah\'dI'0-2
.2a-diazabenzo[c.d]azu/ene (22) .
A mixture of 21 (300 mg. 1.36 mmol). diphenyl phosphorazidate
(375mg, 1.36 mmol) and triethylamine (138 mg, 1.36 mmol) in 25 ml
of ace-tonitrile was stirred at 60°C for 4 h. After addition of 0.5
N HCI (20 ml) thereaction mixture was stirred at room temp. for 2.5
h and worked up asdescribed for 16a to give 234 mg (87%) of 22 as a
colorless solid; m.p.85°C.- C11H17N3 (191.3) mol.-mass 191 (ms).-
IR (KBr): 3360; 2910; 2830cm-I.- IH-NMR (CDCI3): /) (ppm) =
1.37-1.46 (m. 2H, Ha,C-5, Ha,C-6),1.58-1.66 (m, IH, HaxC-7),
1.84-1.96 (m, 2H. Ha,C-4, HeqC-6). 2.03-2.11
(m. 3H, HeqC-4, HeqC-5. HeqC-7), 2.41 (dd. J = 13.9. 11.0 Hz.
IH, HaxC-9),2.70-2.86 (m, 3H, HaxC-5a. Ha,C-8, HeqC-9), 3.93 (ddd,
J = 12.5. 12.5,4Hz, IH, HaxC-3), 4.21 (dd, J = 12.5,5.1 Hz, IH,
HeqC-3), 7.21 (s, IH,HC-I).
Methy/( 3RS .5aSR)-(5a.6 .7.8.-retrahydI'0-3H,5H
-4-o.l'a-/.8a-diaza-acenaphthy/en-3-y/)-acctate (25a)
A mixture of 12a (50 mg, 0.2 mmol) and 100 mg of Pd/C (10%) in
10 mlof acetic acid was stirred at 120°C for 3 h under H, of 70
bar. Then it wasfiltered (CeliteR AFA) and the filtrate was
evap;rated. A satd. aqueoussolution of NaHC03 was added and the
mixture was extracted with EtOAc.The org. layer was dried (MgS04)
and evaporated and the residue wasseparated by flash chromatography
(petroleum ether - EtOAc I: I) to give30 mg (64%) of 25a as a
colorless solid; m.p. 76°C.- ClzHI6N20, (236.3)Calcd. C 61.0 H 6.83
N 11.9 Found C 61.3 H 6.84 N 11.9: mol.-mass 236(ms).- IR (KBr):
2930; 2850; 1740 cm-I._ IH-NMR (CDCI3): /) (ppm) =1.10 (dddd, J =
13; 12.8; 12.5; 3.0 Hz, IH, HaxC-6), 1.91-2.25 (m. 3H,HeqC-6,
HzC-7), 2.74 (d, J = 6.8 Hz, 2H, CH2CO), 2.97-3.02 (m, IH,HC-5a),
3.18 (t, J = 10.7 Hz, IH, HaxC-5), 3.74 (s. 3H, CH3), 3.89 (ddd, J
=12.5, 12.5,5.5 Hz, IH, HaxC-8), 4.13 (dd, J = 10.7,5.1 Hz, IH,
HeqC-5),4.32 (dd, J = 12.5,6.0 Hz, IH, HeqC-8), 5.15 (ddd, J = 6.8,
6.4, 1.7 Hz, I H,Ha,C-3), 7.27 (s, IH, HC-2).
Methy/(3RS .5aRS )-(5a,6.7,8-tetrahydro-3H 5H -4-o.l'a-/
,8a-diaza-acenaphthy/en- 3 -yl}-dimethylacetate (25b)
A mixture of 12d (60 mg, 0.21 mmol) and 100 mg of Pd/C (10%) in
15ml of acetic acid was stirred at 140°C for 5 h under H2 of 60
bar. Then itwas filtered (CeliteR AFA) and the filtrate was
evaporated. The residue wasseparated by flash chromatography
(petroleum ether - EtOAc 6:4) to give22 mg (40%) of 25b as a
colorless oil.- C14H20N203 (264.3) Calcd. C 63.7H 7.63 N 10.6 Found
C 63.5 H 7.69 N 10.7; mol.-mass 264 (ms).- IR(NaCI): 2950; 2870;
1730 cm-I._ IH_NMR (CDCI,): /) (ppm) = 1.07 (dddd,J = 12.5, 12.5.
12.5, 2.9 Hz, I H. Ha,C-6), 1.13 (s. 3H, CCH3), 1.22 (s, 3H,CCH3),
1.90-2.23 (m, 3H, HeqC-6, H2C-7), 2.90-2.96 (m, IH, HC-5a). 3.08(t,
J = 10.3 Hz, IH. Ha,C-5), 3.75 (s, 3H. OCH3), 3.89 (ddd. J = 12.5.
12.5,5.9 Hz, IH, Ha,C-8), 4.08 (dd, J = 10.3,5.1 Hz. IH. HeqC-5),
4.31 (dd, J =12.5. 5.8 Hz, I H. HeqC-8), 5.01 (d, J = 1.5 Hz. IH.
HC-3). 7.21 (s, I H.HC-2).
(3RS .5aSR )-(5a.6 .7,8- Tetrahydro-3H.5 H-4-o.l'a-/ ,8a-dia
za-ace III/phthylcn-3-yl)aceric acid (2Se)
A solution of 2Sa (500 mg. 2.12 mmol) in 20 ml of dioxane and 20
ml ofN NaOH was stirred at room temp. for 4 h. Then the solution
was extracted
-
with ether and the aqueous layer was concentrated. then
acidified to pH 3-4with citric acid (10% in H20) and extracted with
CH2Cl2• The org. layerwas dried (MgS04) and evaporated to give 330
mg (70%) of 25e as acolorless solid; m.p. 192°C.- CIIHI4N203
(222.2) Calcd. C 59.5 H 6.35 N12.6 Found C 59.6 H 5.76 N 12.6;
moL-mass 222 (ms).- IR (KBr): 2950;2870; 2750; 2490; 1710 em-I.-
IH_NMR (CD30D): l) (ppm) = 1.12 (dddd. J= 13.2, 12.5, 12.5,2.5 Hz.
IH, HaxC-6), 1.90-2.25 (m. 3H, lIeqC-6, H2C-7).2.80 (br-d, J = 5.9
Hz. 2H. CH2CO), 2.98-3.05 (m. I H. HC-5a). 3.22 (t. J =10.3 Hz. IH.
HaxC-5). 3.91 (ddd, J = 12.5, 12.5,5.1 Hz, IH. HaxC-8), 4.17(dd, J
= 10.3.5.1 Hz. IH, HeqC-5), 4.34 (dd, J = 12.5.5.9 Hz. IH.
HeqC-8),5.15 (br-t, J = 5.9 Hz, IH. HC-3), 7.35 (s, IH, HC-2).
(3RS ,5aSR)-3 -Aminomethy/-5a .6.7.8-tetrahydro-3H ,5H
-4-oxa-1.8a-diaza-acenaphthy/ene (25d)
A mixture of 25e (220 mg, I mmol), diphenyl phosphorazidate (275
mg,I mmol) and triethylamine (101 mg, I mmol) in 10 ml of
acetonitrile wasstirred at 60°C for 20 h. After the addition of 0.5
N HCI (20 ml) thereaction mixture was stirred at room temp. for 5 h
and worked up asdecribed for 16a to give 145 mg (75%) of 25d as a
colorless oil.-ClOHI5N30 (193.3).- IR (NaC1): 3420; 2930; 2860
cm·'.- 'H-NMR(CDCI3): l) (ppm) = 1.01 (dddd, J = 12.5, 12.5,
12.5,2.2 Hz, IH, HaxC-6),1.93-2.24 (m, 3H, HeqC-6, H2C-7), 2.78
(br-s, 4H, CH2NH2), 2.97-3.04 (m,IH, HC-5a), 3.18 (I. J = 10.3 Hz,
IH, HaxC-5), 3.88 (ddd, J = 12.5, 12.5,5.9 Hz, IH, HaxC-8), 4.15
(dd, J = 10.3,5.1 Hz, IH, lIeqC-5), 4.31 (dd, J =12.5.5.9 Hz, IH,
HeqC-8), 4.82 (br-s, IH, HC-3), 7.31 (s, IH, HC-2).
M ethy/2 ,2-dimethy/-3 -oxo-3 -(4,5.6.7 -tetrahydropyraz%[J
,5-aj-pyridin-3-y/jpropionate (27)
A solution of methyl 2-methylpropionate (357 mg, 3.5 mmol) in 5
ml ofTHF was added dropwise to 10.75 ml of freshly prepared LDA
(0.32 molarin THF) at _?S0c. The reaction mixture was stirred at
this temp. for 15 minand then warmed up to O°C. Subsequently a
solution of 26 (180 mg, Immol) in 5 ml of THF was added dropwise
and then stirred at this temp.for I h. 10 ml of a satd. aqueous
solution of NaHC03 were added and themixture was extracted with
ether. The org. layer was dried (MgS04). evap-orated, and the
residue was purified by flash chromatography (petroleumether -
EtOAc 1:1) to give 170 mg (70%) of 27 as a colorless solid;
m.p.99°C.- C13H18N203 (250.3) Calcd. C 62.4 H 7.25 N 11.2 Found C
62.3 H7.27 N 11.1.- IR (KBr): 2980; 2950; 2930; 2870; 1730; 1650
cm-I.- IH_NMR (CDCI3): l) (ppm) = 1.48 (s, 6H, 2 CCH3), 1.86-1.91
(m, 2H, H2C-5),2,01-2.08 (m, 2H, H2C-6), 3.11 (t, J = 6 Hz, 2H,
H2C-4), 3.68 (s, 3H,OCH3), 4.14 (t. J = 6 Hz, 2H, H2C-7), 7.69 (s,
I H, HC-2).
Receptor Binding Assay
DA receptor binding was performed as described using
eH]-SCH2339018) and eH]-spiroperidoI19) as radioligands in
concentrations of 0.3nM and 0.5 nM, respectively. In the receptor
binding assay for the charac-terization of the DA autoreceptor,
eH]-SND 919 (51 Ci/mmol specificactivity) was used in a
concentration of 0.5 nM. The experimental proce-dure was performed
in analogy to the binding assay with [3H]-spiroperidolas
radioligand. For all receptor binding tests rat brain striatum was
used.
Modified and Extended Behavioura/-Activity Screening. based on
RefL 20,21
All drugs were tested in a minimum of 3 doses (100/50/25 mg/kg)
em-ploying 3 mice (male NMRI mice, 20-33 g) for each dosis. For the
first 30min after the test compound was injected i.p. (dose volume
= 10 m1lkg, in0.9 aqueous NaCI solution or 0.5 tragant suspension)
only fundamentalobservations (e.g .. convulsion, Straub tail,
respiratory depression) were
noted. Then the animals were investigated, including the
following parame-ters: irregular/dyspnoic respiration,
vocalization, restlessness, piloerection,retracted sides, abdominal
cramps, exophthalmus, twitches, convulsion,pinna response, corneal
response, palpebral closure, motor activity, spatialorientation,
!ail position, gait, hyperactivity/vocalization after
stimulation,aggressivity, tremors, body position, righting reflex,
hypothermia, hyper-thermia, lacrimation, dacryorrhea, salivation,
sialhorrhea, diarrhea, skincolor, pupil size, light-pupil response,
body tone, motor coordination, cata-lepsy, hot plate response,
stereotype movements, death. Observations dif-fering from saline
treated control animals were observed again after 4 and24 h. Each
animal was used for one experiment only.
Three mice (male NMRI mice, 20-33 g) in a macrolon cage (type
III)with free access to food and water were placed into a scanner
box (RBM 3,MSE/INTRON, Miinchen/Miinsing, Germany) using
electromagneticalfield for the measurement at 3.45 pm. After 30 min
aqueous 0.9% NaCIsolution was injected i.p. Then the motor activity
was recorded by a separ-ate printer for 2 h. Following the same
schedule at the following day theprocedure was repeated after
injection of the test compound. Totally, 8groups of 3 mice were
investigated using each animal only once. Data wereexamined using
the Hest for paris of observations according to Studellt
andWi/coxon's matched pair signed rank statistic22•23).
J. Delay, P. Deniker, and J.-M. HarJ, Ann. Med. Psychol. 110,
267(1952).
2 For an overview. see: E. Mutschler, Arzneimittelwirkungen, 6th
ed.,Wissenschaftliche Verlagsgesellschaft, Stuttgart 1991.
3 A Carlsson, BioI. Psychatr. 13,3 (1978).4 P.H. Anderson and
E.B. Nielson, Drug News & Perspectives 4, 150
(1991).5 C.A. Seyfried and H. Boettcher, Drugs Fut. 15, 819
(1990).6 M. Abou-Gharbia and J.A. Moyer, in Annual Reports in
Medicinal
Chemistry (ed. J. McCall), Vol. 25, Section I, I (1989).7 L.A.
McQuaid, J.E. Latz, J.A. Clemens, R.W. Fuller. D.T. Wong, and
N.R Mason, J. Med. Chern. 32, 2388 (1989).8 C.S. Schneider and
J. Mierau, J. Med. Chern. 30, 494 (1987); J. Mierau
and G. Schingnitz, BioI. Psychatry 29, I I Suppl., 612 S.
(1991).9 P. Gmeiner, J. Mierau, and G. HOfner, Arch. Pharm.
(Weinheim) 325.
57 (1992).10 N.J. Bach, E.C. Kornfeld, N.D. Jones, M.O. Chaney,
D.E. Dorman,
J.W. Paschal, J.A. Clemens, and E.B. Smalstig, J. Med. Chern.
23, 481(1980).
II Work is still in progress.12 P. Gmeiner and J. Sommer, Arch.
Pharm. (Weinheim) 323, 991
(1990):13 K. Ninomiya, T. Shori, and S. Yamada, Tetrahedron 30.
2151 (1974).14 PJ. Dunn, R Haner, and H. Rapoport, J. Org. Chern.
55, 5017 (1990).15 P. Gmeiner and J. Sommer. Liebigs Ann. Chern.
1991,921.16 For similar observations, see: A.S. Cieplak, J. Am.
Chern. Soc. 103,
4540 (1981).17 Y.-D. Wu, K.N. Houk, J. Florez, and B. Trost, J.
Org. Chern. 56,3656
(1991) and references cited therein.18 W. Billard, V. Ruperto,
G. Crosby, L.c. Iorio, and A. Barnett. Life
Sci.35, 1885 (1984).19 I. Creese, D.R. Burt, and S.H. Snyder,
Life Sci. 17,993 (1975).20 S.lrwin, Psychopharmacologia 13, 222
(1968).21 D.E.S. Champell and W. Richter, Acta Pharmacol. Toxicol.
25. 345
(1967).22 D. Winne. Arzneim.-Forsch.17. 515 (1967).23 RL. Mc
Cornack, J. Amer. Stat. Assoc. 60. 864 (1965). [Ph986]