Contemporary Organic Synthesis Editorial Board Professor G. Pattenden, FRS (Chairman), University of Nottingham Professor P. D. Bailey, Heriot- Watt University Dr S. E. Gibson (nee Thomas), Imperial College of Science, Technology, and Medicine Professor P. J. Kocienski, University of Southampton Professor C. J. Moody, Loughborough University of Technology Professor E. J. Thomas, University of Manchester International Advisory Board PrGfessor E. J. Corey, Harvard University Professor S. Hanessian, Universiti de Montrial Professor M. Julia, Universiti de Paris X I (Paris-Sud) Professor P. D. Magnus, University of Texas at Austin Professor G. Mehta, University of Hyderabad Professor K. C. Nicolaou, The Scripps Research Institute and University of Professor R. Noyori, Nagoya University Professor L.E. Overman, University of California, Irvine Professor L. F. Tietze, University of Gottingen California at Sun Diego, La Jolla Contemporary Organic Synthesis is a bimonthly journal which aims to review and provide perspective in all aspects of methodology, selectivity and efficiency in contemporary synthesis. As well as covering all the principles and methods in functional group chemistry and interconversions, organometallic chemistry and asymmetric synthesis will feature prominently; so too will modern aspects of strategy and computer aided design, biotransformations and protecting group protocols. Special methods and techniques, such as sonochemistry, FVP, electroorganic synthesis and supported catalysis will be included as occasional articles, and the manner in which synthesis addresses problems and provides solutions in biology, medicine, agriculture, the environment and new materials, will also be encompassed.Contemporary Organic Synthesis aims to be proactive, drawing attention to new opportunities and new directions, providing timely information to the synthetic chemist who needs to keep abreast of developments in the field. Although the majority of articles are intended to be specially commissioned, the Society is always prepared to consider offers of articles for publication. In such cases a short synopsis, rather than the completed article, should be submitted to Dr Sheila R. Buxton, Managing Editor, Organic Publications, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, UK.Deputy Editor: Nicole Brooks. Production Editor: Nicola Coward. Technical Editor: Tony Breen. Tel +44 (0) 1223 420066 Fax +44 (0) 1223 420247 E-mail rscl@rsc.org RSC Server http://chemistry.rsc.org/rsc/ Members of The Royal Society of Chemistry may subscribe to Contemporary Organic Synthesis by placing their orders on the Annual Subscription renewal forms in the usual way. All other orders accompanied with payment should be sent directly to The Royal Society of Chemistry, The Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 lHN, England. 1996 subscription rates: EEA f185, USA $350, Canada El90 ‘(plus GST), Rest of the World f190. Contemporary Organic Synthesis is published 6 times a year in February, April, June, August, October and December.Airfreight and mailing in the USA by Mercury Airfreight International Ltd, 2323 Randolph Avenue, Avenel, New Jersey, NJ 07001, USA and at additional mailing offices. Periodicals postage is paid at Rahway, NJ. USA Postmaster: Send address changes to Contemporary Organic Synthesis, c/o Mercury Airfreight International Ltd, 2323 Randolph Avenue, Avenel, New Jersey 07001. All other dispatches outside the UK are by Bulk Airmail within Europe and Accelerated Surface Post outside Europe. 0 The Royal Society of Chemistry, 1996. 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. Typeset in Great Britain by Unicus Graphics Ltd, Horsham, West Sussex Printed in Great Britain by Whitstable Litho Ltd, Whitstable, KentContemporary Organic Synthesis Editorial Board Professor P.J. Kocienski (Chairman), University of Glasgow Professor P. D. Bailey, Heriot- Watt University Dr S . E. Gibson (nee Thomas), Imperial College of Science, TechnoloD, and Medicine Professor R. F. W. Jackson, University of Newcastle Professor C. J. Moody, University of Exeter Professor G. Pattenden, FRS, University of Nottingham Professor R. J. K. Taylor, University of York International Advisory Board Professor E. J. Corey, Haward University Professor S . Hanessian, Universitk de Montreal Professor M. Julia, Universite de Paris X I (Paris-Sud) Professor P.D. Magnus, University of Texas at Austin Professor G. Mehta, University of Hyderabad Professor K. C. Nicolaou, The Scripps Research Institute and University of Professor R. Noyori, Nagoya University Professor L. E. Overman, University of California, Iwine Professor L. F. Tietze, University of Gottingen California at Sun Diego, La Jolla Contemporary Organic Synthesis is a bimonthly journal which aims to review and provide perspective in all aspects of methodology, selectivity and efficiency in contemporary synthesis. As well as covering all the principles and methods in functional group chemistry and interconversions, organometallic chemistry and asymmetric synthesis will feature prominently; so too will modern aspects of strategy and computer aided design, biotransformations and protecting group protocols.Special methods and techniques, such as sonochemistry, FVP, electroorganic synthesis and supported catalysis will be included as occasional articles, and the manner in which synthesis addresses problems and provides solutions in biology, medicine, agriculture, the environment and new materials, will also be encompassed. Contemporary Organic Synthesis aims to be proactive, drawing attention to new opportunities and new directions, providing timely information to the synthetic chemist who needs to keep abreast of developments in the field. Although the majority of articles are intended to be specially commissioned, the Society is always prepared to consider offers of articles for publication.In such cases a short synopsis, rather than the completed article, should be submitted to Dr Sheila R. Buxton, Managing Editor, Organic Publications, The Royal Society of Chemistry: Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF, UK. Deputy Editor: Dr Roxane Owen. Production Editor: Nicola Coward. Technical Editor: Dr Helen Saxton. Tel +44 (0) 1223 420066 Fax +44 (0) 1223 420247 E-mail perkin@rsc.org RSC Server http://chemistry.rsc.orglrsc/ Members of The Royal Society of Chemistry may subscribe to Contemporary Organic Synthesis by placing their orders on the Annual Subscription renewal forms in the usual way. All other orders accompanied with payment should be sent directly to The Royal Society of Chemistry, The Distribution Centre, Blackhorse Road, Letchworth, Herts SG6 lHN, England.1997 annual subscription rate: f199.00; US$358.00. Customers in Canada will be charged the sterling price plus a surcharge to cover GST. Contemporary Organic Synthesis is published 6 times a year in February, April, June, August, October and December. Airfreight and mailing in the USA by Mercury Airfreight International Ltd, 2323 Randolph Avenue, Avenel, New Jersey, NJ 07001, USA and at additional mailing offices. Periodicals postage is paid at Rahway, NJ. USA Postmaster: Send address changes to Contemporary Organic Synthesis, c/o Mercury Airfreight International Ltd, 2323 Randolph Avenue, Avenel, New Jersey 07001. All other dispatches outside the UK are by Bulk Airmail within Europe and Accelerated Surface Post outside Europe. The Royal Society of Chemistry, 1997. 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. Typeset in Great Britain by Unicus Graphics Ltd, Horsham, West Sussex Printed in Great Britain by Whitstable Litho Ltd, Whitstable, Kent