Pericyclic Reactions

Chapman and Hall Chemistry Textbook Series

CONSULТING EDIТORS

R. Р. Ве11, М.А., Ноп. LLD., F.R.S., Professor of Chemistry at theUniversity of Stir1ing.

N. N. Greenwood, Ph.D., Sc.D., Professor of Inorganic and StructuralChemistry at the University of Leeds.

R. О. С. Norman, М.А., D.Sc., Professor of Chemistry at the University of York.

OTHER ТITLES IN ТНЕ SERIES

Symтetry in Molecules J. М. Ho11as

lntroduction to Molecular Photochemistry С. Н. J. We11s

N.M.R. and Chemistry J. W. Akitt

Chemistry о/ the Non-Metals Р. Powel1 and Р. L. Timms

Principles and Applications о/Electrochemistry D. R. Crow

Organometallics in Organic Synthesis J. М. Swan and О. St. С. В1асk

Chapman and Hall Chemistry Textbook Series

CONSULTING EDITORS

R. P. Bell, M.A., Hon. LLD., F.R.S., Professor of Chemistry at the University of Stirling.

N. N. Greenwood, Ph.D., Sc.D., Professor of Inorganic and Structural Chemistry at the University of Leeds.

R. O. C. Norman, M.A., D.Sc., Professor of Chemistry at the University of York.

OTHER TITLES IN THE SERIES

Symmetry in Molecules 1. M. Hollas

Introduction to Molecular Photochemistry C. H. 1. Wells

NM.R . and Chemistry 1. W. Akitt

Chemistry of the Non-Metals P. Powell and P. L. Timms

Principles and Applications of Electrochemistry D. R. Crow

Organometallics in Organic Synthesis 1. M. Swan and D. St. C. Black

Pericyclic Reactions

G. В. Gill

М. R. Willis

Department of Chemistry, University of Nottingham

LONDON

CHAPMAN AND HALL

First published in 1974Ьу Chapтan and Hall Ltd.

11 New Fetter Lane, London ЕС4Р 4ЕЕ

© 1974 G. В. Gill and М. R. Willis

ISBN-13 978-0-412-12490-7 e-ISBN-13: 978-94-009-5718-3DOI: 10.1007/978-94-009-5718-3

This limp bound edition is sold subject to thecondition that it shaH not, Ьу way of trade or

otherwise, Ье lent, re-sold, hired out, orotherwise circu1ated without the publisher's

prior consent in аnу form of binding or coverother than that in wblch it is published and

without а similar condition including thiscondition being imposed оп the subsequent

purchaser.АН rights reserved. No part of this book

тау Ье reprinted, or reproduced or utilized inаnу form or Ьу аn electronic, mechanica1 or

other means, now known or hereafter invented,inc1uding photocopying and recording, or inаnу infom:lation storage and retrieval system,

without permission in writing from thePublisher.

Distributed in the U.S.A.Ьу Halsted Press, а Division

of John Wi1ey and Sons, Inc., New York

First published in 1974 by Chapman and Hall Ltd.

11 New Fetter Lane, London EC4P 4EE

lSBN-13 978-0-412-12490-7

© 1974 G. B. Gill and M. R. Willis

e-lSBN-13 : 978-94-009-5718-3 DOl: 10.1007/978-94-009-5718-3

This limp bound edition is sold subject to the condition that it shall not, by way of trade or

otherwise, be lent, re-sold, hired out, or otherwise circulated without the publisher's

prior consent in any form of binding or cover other than that in which it is published and

without a similar condition including this condition being imposed on the subsequent

purchaser. All rights reserved. No part of this book

may be reprinted, or reproduced or utilized in any form or by an electronic, mechanical or

other means, now known or hereafter invented, including photocopying and recording, or in

any info~ation storage and retrieval system, without permission in writing from the

Publisher.

Distributed in the U.S.A. by Halsted Press, a Division

of John Wiley and Sons, Inc., New York

Contents

Preface

Atomic and то1есu1ат orbita1s

pagevii

2 Aromaticity 41

3 The stereochemica1 requirements of concerted pericyclic reactions 63

4 The concept of the conservation of orbita1 symmetry 99

5

6

Alternative rationalizations-the aromaticity of pericyc1ictransition states

The organic chemistry of pericyclic reactions

128

144

Appendix 1 Deteтminants

Appendix 11 The solution of secu1ar equations

Appendix 111 НМО treatment of the сус1ортореnу1 system

Appendix IV Answers to problems

References

Index

209

213

216

221

231

234

Preface

Мо1еси1агorbita1 theory has had some notable successes in the ana1ysis ofindividua1 organic reactions and in corre1ations between reaction series. Gen­егаllу the theory has Ьееп invoked to exp1ain known chemica1 phenomena,and rather infrequent1y [ог broad1y-based predictions. In 1965 Woodwardand НоПтапп published а series of papers оп the то1еси1агorbita1 inter­pretation of various types of concerted cyc10-addition reactions, whichhitherto had Ьееп rather роог1у understood. Because these processes (nowknown as pericyclic reactions) had great synthetic importance, and becausethe Woodward-Hoffmann theory was stated so explicit1y as to allow [ог usefu1and far-reaching predictions to Ье made, the genera1 acceptance of the so-calledWoodward-Hoffmann Ru1es was very rapid. Judging from the vast number ofpublications that have appeared, а great dea1 of experimental effort has Ьееп

channelled into this genera1 area since that time, the results of which provideа vindication of the ru1es. The theoretica1 basis of Woodward and Hoffmann'smethod has, however, Ьееп the subject of criticism and controversy, and а

питЬег of alternative theoretica1 methods have a1so appeared.Мапу university departments (inc1uding оur own) have for some time

covered pericyclic reactions in their undergraduate and graduate courses.Because aims, teaching methods, and persona1 preferences differ wide1y, eachof the various theoretica1 methods have achieved some currency. We havesought to р1асе these methods in some sort of perspective. The book isintended to Ье introductory, being aimed primarily at fina1 year undergraduatesand first year postgraduates.

Readers with а limited know1edge of то1еси1аг orbita1 theory and itsapplications to aromaticity will find concise coverage of the various pointspertinent to the 1ater discussions in Chapters 1 and 2. Some тау prefer tostart in at Chapter 3, whi1st others with some know1edge of concerted [еас­

tions, seeking c1arification оп specific problems, wil1 wish to read individua1vii

PERICYCLIC REACTIONS

Sections in Chapters 4 to 6. We hope that the organization of the book willprove suitable for the rather heterogeneous requirements of the readershipfor which it was intended. А few problem exercises have Ьееп written intoChapters 1 to 5, and the answers appear in Appendix IV. The Appendices 1 toIII were created in order to avoid digression or clutter in Chapters 1 and 2.

Because of the introductory nature of this book, prominence has Ьееп

given among the references to review articles; original papers are cited onlyoccasionally. The literature in this field continues to accrue rapidly, and hencein the discussion of experimental resu1ts (Chapter 6) limitations оп space haveprecluded апу sort of exhaustive coverage.

Finally, we thank numerous colleagues who have helped either directly orindirectly in formulating the content and lay-out of this manuscript. We aregrateful to ош fami1ies and to the publishers for their forebearance.

Nottinghaт

Septeтber 1973

уш

G. В. GillМ. R. Willis