Natural Product Reports Editorial Board Professor G. Pattenden (Chairman) University of Nottingham Dr. D. V. Banthorpe University College London Professor M. F. Grundon University of Ulster at Coleraine Professor F. D. Gunstone University of St. Andrews Dr. J. R. Hanson University of Sussex Dr. R. B. Herbert University of Leeds Dr. T. J. Simpson University of Edinburgh Natural Product Reports is a journal of critical reviews published bimonthly which is intended to foster progress in the study of natural products by providing reviews of the literature that has been published during well-defined periods. For any individual topic successive reviews will deal with consecutive periods and while the coverage that was provided by the Specialist Periodical Reports on 'Aliphatic and Related Natural Product Chemistry' 'The Alkaloids' 'Biosynthesis' and 'Terpenoids and Steroids' will be continued this will be supplemented by occasional reviews of areas of both general and specific interest to workers in these and in other fields.Bimonthly publication allows greater flexibility than the annual or biennial publication of volumes of each of the series of Specialist Periodical Reports mentioned above in that individual reviews can be published as they become available. All articles in Natural Product Reports are commissioned by members of the Editorial Board. Natural Product Reports (ISSN 0265-0568) is published bimonthly by The Royal Society of Chemistry Burlington House London W 1V OBN England. 1985 Annual Subscription Price U.K.f125.00 Rest of World f131.00 USA. $242.00. Change of address and orders with payment in advance to The Royal Society of Chemistry The Distribution Centre Blackhorse Road Letchworth Herts. SG6 lHN England. Air Freight and mailing in the U.S. by Publications Expediting Service Inc. 200 Meacham Avenue Elmont NY 1 1003. U.S. Postmaster send address changes to Natural Product Reports Publications Expediting Service Inc. 200 Meacham Avenue Elmont NY 11003. Second-Class postage paid at Jamaica NY 11431-9998. All other despatches outside the U.K. are by Bulk Airmail within Europe and Accelerated Surface Post outside Europe. Printed in the U.K. 0The Royal Society of Chemistry 1985 All Rights Reserved No part of this publication may be reproduced stored in a retrieval system or transmitted in any form or by any means electronic mechanical photographic recording or otherwise without the prior permission of the publishers. Computer typeset by SB Datagraphics. Printed in Great Britain by Spottiswoode Ballantyne Printers Ltd Subscription rates for 1985 U.K. f125.00 Overseas f131.OO U.S.A. USS242.00 Subscription rates for 1986 are U.K. f130.00 Overseas f143.00 U.S.A. USS252.00 Subscription rates for back issues (1984) are U.K. f120.00 Overseas f126.00 U.S.A. USS240.00 Members of the Royal Society of Chemistry should order the journal from The Membership Officer The Royal Society of Chemistry 30 Russell Square LONDON WClB 5DT England