Advances In Heterocyclic Chemistry, Vol. 56

Advances in Heterocyclic Chemistry Volume 56 Editorial Advisory Board R. A. Abramovitch, Clemson, South Carolina A. T. Balaban, Bucharest, Romania A. J. Boulton, Norwich, England H. Dorn, Berlin-Bohnsdorf, Germany J. Elguero, Madrid, Spain S. Gronowitz, Lund, Sweden 0. Meth-Cohn, Sunderland, England C . W. Rees, FRS, London, England E. C. Taylor, Princeton, New Jersey M. TiSler, Ljubljana, Slovenia J. A. Zoltewicz, Gainesville, Florida Advances in HETEROCYCLIC CHEMISTRY Edited by ALAN R. KATRITZKY, FRS Kenan Professor of Chemistry Department of Chemistry University of Florida Gainesville, Florida Volume 56 ACADEMIC PRESS, INC. Harcourt Brace Jovanovicb, Publishers San Diego New York Boston London Sydney Tokyo Toronto This book is printed on acid-free paper. @ Copyright 0 1993 by ACADEMIC PRESS, INC. All Rights Reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Academic Press, Inc. 1250 Sixth Avenue, San Diego, California 92101-4311 United Kingdom Edition published by Academic Press Limited 24-28 Oval Road, London NW 1 7DX Library of Congress Catalog Number: 62- 13037 International Standard Book Number: 0-12-020756-7 PRINTED IN THE UNITED STATES OF AMERICA 939495969798 QW 9 8 7 6 5 4 3 2 1 Contents CONTRIBUTORS .................................................................................... PREFACE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . vii ix 2,3-Dihydro-l,Cdiazepines and 2,3-Dihydro-1 ,Cdiazepinium Salts DOUGLAS LLOYD AND HAMISHMCNAB 1. 11. 111. IV. V. VI. VII. VIII. IX. X. XI. Introduction ................................................................................... Preparation of Dihydrodiazepines and Dihydrodiazepinium Salts . . . . . . . . . . . . Stability of Dihydrodiazepines and Dihydrodiazepinium Salts . . . . . . . . . . . . . . . . Structure Spectra .................................................................................... Electrophilic Substitution Reactions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Reduction of 6-NitrodihydrodiazepiniumSalts; 6-Aminodihydrodiazepinium Salts .................................................. Reactions with Nucleophiles ........................................................... Cyclo-addition Reactions ............................................................ Rearrangement Reactions ............................................................... Electrochemical Studies ................................................................ References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2 I1 15 17 23 33 33 38 39 40 44 Ring Transformations of Five-Membered Heterocycles N I C O LVIVONA, ~ SILVESTRE BUSCEMI,VINCENZOFRENNA, AND GIUSEPPECUSMANO I. Introduction ................................................................................ 11. Rearrangements Involving the Pivotal Nitrogen Atom in the Starting Ring . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111. Rearrangements Involving the Pivotal Sulfur Atom in the Starting Ring ... IV. Rearrangements Involving the Pivotal Carbon Atom in the