PHOTOREARRANGEMENT OF BICYCLO[2.2.1]HEPTENE-2-CARBONITRILE

PHOTOREARRANGEMENT OF BICYCLO[2.2.1]HEPTENE-2-CARBONITRILE.

THE OBSERVATION OP 1,2.AND 1,3-SIGMATROPIC SHIFTS-

by

\~ Susan Vaitekunas. B.Sc.

~

A Thesi~

Submitted to the School of Graduate Studies inPartial Fulfullment of the Requirement for the

Degree .Master of Science

McMaster UniversityNovember, 1981

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PHOTOREARRANGEMENT OF BICYCLO[2.2.1]HEPTENE-2-CARBONITRILE ~

THE -OBSERVATION OF 1,2 AND 1,3-SIG~~TROPIC SHIFTSl

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to my parents

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Master of Science (1981)(Chem~ stry)

McMaster Un;ver$i~y

Hamilton, Ontario,

.TITLf: Photorearrangement of Bicyclo[2.2.1)heptene-2-carbanitrile

Observation of 1,2 and 1,3-S1gmatropic Shifts\

.AUTHOR: Susan Vaitekunas, B.Sc. (Concordia University, Montreal, Quebec)

SUPERVISOR: Dr. J.J. McCullough

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NUMBER OF -P~GES:' xiii, 106

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•ABST-RACT

The ~,e-unsaturated nitrile, bi~yclo[2.2.1]heptene-2-carbonitril~,I,

was synthesized from norcamphor. Irradiation in hexane with unfiltered

light from a medium pressure mercury arc lamp resulted in its conversion

r:

to two products, bicyclo[4.1.0]hept-2-ene-l-carbonitr,il~, 11, and tricyclo-.[4.1.0.0.3,71heptane-7-carbonitrile, III, in a 20:1 ratio.

/1 hv~CN-'-h-e.x-a-ne~)

I III

The structure-of the major rearrangement product, II, was proven by .

X-ray crystallography of its crystalline derivative, 1-methylamino-bicyclo-.

[4.1.0] hept-2-ene-p-bromobenzenesul fonate. The m!nor product, III, was identi-~

fied by catalytic hydrogenation to 7-cyanobicyclo[2.2.1]heptane and vpc com-

parison with authentic 7-cyanobicyclo[2.2.1]heptane synthesized from bicyclo­

[2.2.1]heptane-7-carboxylic acid.

The photorearrangement of I to II and III are orbital symmetry-allowed

photochemical 1,3 and 1,2-sigmatropic shifts, respectively. The 1,3-sigmatropic

shift has not been previously,observed in the photochemistry of a,a-unsaturated

nitriles while the 1,2 shift was observed in,the photorearrangement of

1-cyanocyclohexenes. Further experiments are needed to determine whether or

not the rearrangements are concerted or diradical in nature.

Preliminary experiments on the related compound, bicyclo[3.2.0]oct-2­

ene-3-carbonjtrile, IV, synthesized from norbornene,indicate that it probably

undergoes the same type of rearrangements as I. The ratio for 1,3,to 1,2

a bond shifts seems to be 3:2 in this case.-

d:>-CNIV

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ACKNOWLEDGEMENTS,

I would like to t~ank my supervisor, Dr. J.J. McCullough for his

help, advice, and encouragement in this research. I would also like to

express my gratitud~ to Keith MacInnis for his suggestions and support.

Thank you to Dr. C.J.L. Lock and R. Faggiani for the crystal structure• I

determination, to F.A. Ramelan who obtained ,the mass spectra, to B. Sayers

for running the 13C nmr spectra, to Dr. J. Warkentin who supplied the sample

of bicyclo[2.2.1]heptane-l-carboxylic acid, and to Mrs. Gayle Griffin who

typed this thesis.

Finally I would like to offer my sincere thanks ,to the National

Science and Engineering Research Council and McMaster University who,

provided me with financial assistance.

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ABSTRACT

ACKNOWLEDGEMENTS

TABLE OF CONTENTS

LIST OF FIGURES

LIST Of" TABLES

LIST',OF SCHEMES

ABBREVIATIONS

I INTRODUCTION

I I

TABLE OF CONTENTS

A. Organic Photochemistry

B. Pericyclic Reactions

(i) Exocyclic Reactions

(ii) Cycloaddition Reactions

(ift) Sigmatropic Rearrangements

C. Olefin Solution Photochemistry

(i) General Comments

(ii) Cis-Trans Isomerization

(iii) Dimerization-[2+2]Cycloaddition

(iv) Direct and Sensit5zed Irradiation of Cycloalkenes

in Hydroxylic Solvents

(v) Carbene Intermediates

(vi) Reactions Involving lt3-H Shifts

D. Photochemistry of a,B-Unsaturated Nitriles

RESULTS

A. Synthesis of Bicyclo[2.2.1]Heptene-2-carbon~trile(135}

(i) Conversion of Norcamphor (136) to 2,2-dichlorobicytl0

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iii

iv

viii

ix

x

xi

1

1

4

4

'6

7

10

10 .,

11

13

16

22

32

35

42

42

42

Table of Contents continued

(2.2.1Jheptane (137)

(ii) Dehydrohalogenation of 2t 2-dichlorobicycloI2.2.1Jheptane 42

(137)

(iii) Conversion of 2-Ghlprobicyclo{2.2.1Jheptene (11[) to 44

.Bicyclo(2.2.1Jhepterie-2-carbo~itrile (135). • •

B. Irradiation of Bicyclo[2.2.1Jheptene-2-carbonitrile (135) 46

C. Identification of the Major Rearrangement Product from Irradia- 47-

tion of Bicyclo[2.2.1]heptene-2-carbonitrile. (135).

(~) Synthesis of Bicyclo[4.1.0]heptane-1-carbonitrile (liL) 50

(ii) Attempts to Hydrogenate the Major Photorearrangement 53

Product from Irradiation of 135,

(iii) Permanganate Oxidation of the Major Rearrangement Product 55

(iv) Attempts to Detenmine Presence of Bicyclo[3.2.1Jhept-2- 56

ene Carbon Skeleton by Pyrolysis

(v) Attempted Synthesi~ of Bicyclo[3.2.0Jheptane-l·Carbonitrile 58

Table of Contents continued

acid (181) to Bicyclo[3.2.0]heptane-l-carbonitrile (175)

O. The Crystal Structure of I-Methylaminobicyclo[4.1.0}hept-2-ene­

brosylate (193)

E. Identificatio~ of Minor Photo product From Irradiation of

Bicyclo[2.2.1]heptene-2-carbonitrile (135)

F. Synthesis and Irradiation of Bicyclo[3.2.0]oct-2-ene-3-carboni-

67

71-

73

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tril e (197)

(i) Formation of 3,4-Dibromobicyclo[3.2.1]oct-2-ene (198) by 74

Addition of Dibromocarbene to Norbornene Y22}

(ii) 'Allylic Reduction of 3,4-0ibromobicyclo[3.2.0]oct-2-ene '75

(198)

(iii) Conversion of 3-Bromobicyclo[3.2.0]oct-2-ene (199) to 75

Bicyclo[3.2.0]oct-2-ene-3-carbonitrile (197)

{iv} Exploratory Photolysis of Bicyclo[3.2.0]oct-2-ene-3- 76

carbonitrile (197)

III' EXPERIMENTAL 79

Materials 79

Instruments 79

A. Synthesis of Bicyclo[2.2.1]heptene-2-carbonitrile (135) 80

(i) Norcamphor (136) + 2,2-0ichlorobicyclo[2.2.1]heptane.(137) 80

(ii) Dehydrohalogenation of 2,2-0ibromobicyclo[2.2.1}heptane 80

(137) to 2-Chlorobicyclo[2.2.1Jhepten~ (138)

(iii) Conversion of 2-Chlorob1cyclo[2.2.1]hePtene (138) to 81

Bicyclo[2.2.1)heptene-2-carbonitrile (135)

B. Irradiation of Bicyclo[2.2.1]heptene-2-carbonitrile (135) 82

C. Synthesis of Bicyclo[4.1.0)heptane-l-carbonitrile (liL) 83

..Table of Contents continued

(i) Synthesis of 1-Cyanocycl~hexene (~) 83

(i i). Preparation of Trimethyl oxosul foxoni um Iodi de (148) 84

(iii) Generation of Dimethyloxosulfonium methyl ide (~) and 84

Re~ction with l-cyanocyclohexene (i29)

D. Synthesis of Bicyclo[3.2.0)heptane-1-carbonitrile (175)-,

(i) Conversion of 1,3,5~Cycloheptatriene (178) to 1,3­

Cycloheptadiene-t-carboxylic acid (179)

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Photochemical Isomerization of 1,3-Cycloheptadiene-1-

carboxylic acid to Bicyclo[3.2.0]hept-6-ene-1-carboxylic·

acid (180)

(iii) Hydrogenation of Bicyclo[3.2.0)hept-6-ene-1-carboxylic 87

acid (180)

(iv) Conver-sion of Bicycl~[3.2.0)heptane-1-carboxylicacid 88

(181) to Bicyclo[3.2.0)heptane-l-carbonitrile (175)

E. Preparation of Bicyclo[4.1.0)hept-2-ene-1-carbonitrile Deriva- 89

tive For X-Ray Work

(i) Reduction of Bicyclo[4.1.0)hept-2-ene-l-carbonitrile (148) 89

(ii) Preparation of I-Methylaminobicyclo[4.1.0)hept-2-ene 90

Brosyl ate (ill)

F. Identification of Minor Rearrangement Product from Irradiation 90

of Bicyclo[2.2.1)heptene-l-carbonitrile (135)

(i) Hydrogenation of 7-Cyanotricyclo[4.1:0.03,7)heptane 90

(ii) Synthesis of 7-Cyanobicyclo[2.2.1]heptane (195) from 91

Bicyclo[2.2.1)heptane-7-carboxylic acid (196)-IG. Synthesis of Bicyclo[3.2.11oct-2-ene-3-carbonitrile (197) 92

(i) Addition of Dibromocarbene to Norbornene (22) 92

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Table of Contents continued

(ii) The Reduction of 3t4-Dibromobicyclo[3.2.1}oct-2~ene(198) 92

to 3-Bromobicyclo[3.2.11oct-2-ene (1.22.).

(iii) Conversion of 3-Bromobicyclo[3.2.11oct-2-ene (~~) to - 93"

Bicyclo(3.2.1]oct-2-ene-3-carbonitrile (197)

H. Exploratory Photolysis of B;cyclo[3.2.1]oct'~-ene-3-carbonitrile 94,

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(197)

IV CONCLUSION

References

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95

104

Figure 1.

Figure 2.

Figure 3.

LIST OF FIGURES

Crystal Structure of I-methylaminobicyclo[4.1.0]hept-2­

ene brosylate (121)

Crystal packing of 1-methylaminobicyclo[4.1.0]hept-2-ene

brosylate (193)

Molecular Orbits Involved in Competing 1,2 and 1,3-Sigma­

tropic Shifts in Bicyclo[2.2.1]heptene-2-carbonitrile

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68

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99

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LIST OF TABLES

Rules for Symmetry.Allowed Electrocyclic Reactions

Rules for Symmetry-Allowed Cycloaddition Reaction"

Rules for Symmetry-Allowed Sigmatropic Rearrangements

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Table 1.

Table 2.

oSelected Interatomic Distances (A) and Angles (deg.)

of I-methylaminobicyclo[4.1.0]hept-2-ene brosylate (193)

Best Planes (193)

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LIST OF SCHEMES

Rearrangement of 2,2,5,5-tetradeuterocyclohexene (Intermediate

70)

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II Rearrangement of 2,2,5,5-tetradeuter~cyclohexene (Intermediate 29

11)

III Rearrangement of 2,2,5,5-tetradeuterocyclohexene (Intermediate 29

]1) .

IV Synthesis of Bicyclo[2.2.1]Heptene-2-carbonitrile (135) 4Z

V Synthesis of the Methyl Esters of 1-Cyanocyclobutane-1,2-dicar- 56

boxylic acid (160) and Cyclobutane-1,1,Z-tricarboxylic acid (161)

VI Synthesis of Bicyclo[3.2.0]heptane-1-carbonitrile 60

VII Attempted Conver~ion of 1,3-cycloheptadiene-1-carboxylic acid (179) 62

to 1,3-cycloheptadiene-1-carbonitrile (184)

VIII Mechanism for Conversion of Carboxylic Acids to Nitriles by ·65

Chlorosulfonyl Isocyanate

IX Synthesis of p-bromosulfonamide of Bicyclo[4.1.0]hept-2-ene-l- 67

carbonitrile (143)

X Identification of Tricyclo[4.1.0.03 ,7]heptane-7-carbonitrile (194) 72

XI Synthesis of Bicyclo[3.2.1]oct-2-ene-3-carbonitrile (197) 74

XII Reartangements of Bicyclo[2:2.1]heptene-2-carbonitrile eill} 95

via 1,3-Sigmatropic Shifts

XI II Rearrangement of Bicyclo[2.2.1]heptene-2-carbonitrile (..ill.) by 96

1,3-shift (diradical mechanism)

XIV Rearrangement of bicyclo[2.2.1]hepten~-2-carbonitrile(..ill.) 98

via 1,2-Shift

XV Photorearrangement of Bicyclo[3.2.1loct-2-ene-3-carbonitrile (197) 101

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A

atm

bp

C

em-1em

CSI

d

deg

DMF

OMSO

g

g

H-

hv

Hz

• IR

ISC

J

kcal

1

LIST OF ABBREVIATIONS

angstrom

atmosphere

boil ing point

celsius

aibromocarbene

centimeter,

reciprocal centimeters

chlorosulfonyl isocyanate

doublet

degrees

dimethylformamide

dimethylsulfoxide

diethyl ether

electron volt

gas

gram

hydrogen atom

light

hertz

infrared

intersystem crossing

coupling constant

kilocalorie

kinetic hydrogen 'isotope effect

potassium tert-butoxide

1iter

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