Advances in Heterocyclic Chemistry Volume 36 Editorial Advisory Board R. A. Abramovitch A. Albert A. T. Balaban A. J. Boulton H. Dorn S . Gronowitz T. Kametani C. W. Rees Yu. N. Sheinker E. C. Taylor M. TiSler J. A. Zoltewicz Advances in HETEROCYCLIC CHEMISTRY Edited by ALAN R. KATRITZKY FRS Kenan Professor of Chemistry Depurtment of Chemist? Universiiy of Florida Guinesville, Florida Volume 36 ACADEMIC PRESS, INC. (Xi-urt Orlando %rOnb Brace Jovanovioh, Publishers) San Diego New York London Montreal Sydney Tokyo COPYRIGHT @) 1984, BY ACADEMIC PRESS, INC. ALL RIGHTS RESERVED. NO PART OF THlS PUBLICATION MAY BE REPRODUCED OR TRANSMITTED IN ANY FORM OR BY ANY MEANS, ELECTRONIC OR MECHANICAL, INCLUDING PHOTOCOPY, RECORDING, OR A N Y INFORMATION STORAGE AND RETRIEVAL SYSTEM, WITHOUT PERMISSION IN WRITINQ FROM THE PUBLISHER. ACADEMIC PRESS,INC. Orlando, Florida 32887 Unired Kingdom Edition published by ACADEMIC PRESS. INC. ( L O N D O N ) LTD. 24/28 Oval Road, London NWl7DX LIBRARY OF CONGRESS CATALOG CARD NUMBER: I S B N 0-12-020636-6 PRINTED IN 'THEUNITED STATES OF AMERICA 84 85 86 87 981 6543 2 1 62- 1 3037 Contents . CONTRIBUTORS PREFACE. , . . , . . . , . . . . . . . . . . . vii ix Conformational Equilibria in Nitrogen-Containing Saturated Six-Membered Rings TREVOR A . C R A B B AND ALANR. KATRITZKY 1. Introduction . . . . . . , . . . . . . . . . , . . . . . . . 11. Methods of Investigating Conformations and Conformational Equilibria . . . . . 111. Results for Individual Ring Systems . . . . . . . . . . . . . . . . 3 7 58 Applications of Phase Transfer Catalysis in Heterocyclic Chemistry ROGER J . GALLO. MIECZYSLAW MAKOSZA, H E N RJ.-M. ~ Dou, AND PARlNA HASSANALY I. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 11. Heterocyclizations . . . . . . . . . . . , . . . . . . . . . . 111. Modifications of Substituents on Heterocyclic Compounds . . . . . . . . . IV. Heterocyclic Ring Transformations . . . . . , . . . . . . . . . . . V. Heterocyclic Intermediates and Catalysts . . . . , . . . . . . . . . . VI. Conclusion . . . . . , . . . . , . . , . . , . . . . . . . 176 181 195 220 227 233 Electrolysis of N-Heterocyclic Compounds (Part 11) HENN~NG LUNDAND IBRO TABAKOV~C I . Introduction . . . . . . . . . . . . . . 11. Methods . . . . . . . . . . . . . . . 111. Electrolytic Formation of Heterocyclic Systems . . IV. Electrolytic Reactions of Heterocyclic Systems . . . V. Electrolysis of Substituted Heterocycles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 237 253 286 324 . 345 346 393 405 . . . . . . . . The Chemistry of Pyrazolopyridines C. R . HARDY 1. 11. 111. IV. Introduction . . . Methods of Synthesis Chemical Reactions . Structure and Physical INDEX CUMULATIVE . . . . . . . . . . . , Properties OF TITLES , , . . . . . . . . . . . . . . . . . . . . . . . . . . . , V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .