Contemporary Organic Synthesis Editorial Board Professor G. Pattenden, FRS (Chairman), University of Nottingham Professor P. D. Bailey, Heriot- Watt University Professor P. J. Kocienski, University of Southampton Professor C. J. Moody, Loughborough University of Technology Dr S. E. Thomas, Imperial College of Science, Technology, and Medicine Professor E. J. Thomas, University of Manchester International Advisory Board Professor E. J. Corey, Harvard University Professor S. Hanessian, Universite' de Montrkal Professor M. Julia, UniversitP 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 California at Sun Diego, La Jolla Professor R.Noyori, Nagoya University Professor L. E. Overman, University of California, Irvine Professor L. F. Tietze, University of Gottingen 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 the Senior Editor (Reviews), Books and Reviews Department, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF.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. 1994 subscription rate: EC &150, USA $282, Canada &169 (plus GST), Rest of the World &161. Air freight and mailing in the USA by Publications Expediting Inc., 200 Meacham Avenue, Elmont 1103; USA Postmaster, send address changes to Contemporary Organic Synthesis, Publications Expediting Inc. Second class postage is paid at Jamaica, New York 11431. All other dispatches outside the UK are by Bulk Airmail within Europe and Accelerated Surface Post outside Europe.0 The Royal Society of Chemistry, 1994 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 by Unicus Graphics Ltd Printed in Great Britain by Whitstable Litho LtdContemporary Organic Synthesis Editorial Board Professor G. Pattenden, FRS (Chairman), University of Nottingham Professor P. D. Bailey, Heriot- Watt University Dr S. E. Gibson (nek 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 Professor E. J. Corey, Harvard University Professor S. Hanessian, Universitk de Montrkal Professor M. Julia, Universitk de Paris XI (Paris-Sud) Professor P. D. Magnus, University of Taus 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, and 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 sdbmitted to the Senior Editor (Reviews), Books and Reviews Department, The Royal Society of Chemistry, Thomas Graham House, Science Park, Milton Road, Cambridge CB4 4WF. 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. 1995 subscription rate: EEA &165, USA $303, Canada El73 (plus GST), Rest of the World &173. Air freight and mailing in the USA by Publications Expediting Inc., 200 Meacham Avenue, Elmont 1103; USA Postmaster, send address changes to Contemporary Organic Synthesis, Publications Expediting Inc. Second class postage is paid at Jamaica, New York 11431. All other dispatches outside the UK are by Bulk Airmail within Europe and Accelerated Surface Post outside Europe. 0 The Royal Society of Chemistry, 1995 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 by Unicus Graphics Ltd Printed in Great Britain by Whitstable Litho Ltd