Art in Biosynthesis. The Synthetic Chemist's Challenge PDF
Preview Art in Biosynthesis. The Synthetic Chemist's Challenge
ACADEMIC PRESS RAPID MANUSCRIPT REPRODUCTION Art in Biosynthesis The Synthetic Chemist's Challenge Volume I Darshan Ranganathan Subrannania Ranganathan Department of Chemistry Indian Institute of Technology Kanpur Foreword by D.H.R. Barton Imperial College, London ACADEMIC PRESS New York San Francisco London 1976 A Subsidiary of Harcourt Brace Jovanovich, Publishers COPYRIGHT © 1976, 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. Ill Fifth Avenue, New York, New York 10003 United Kingdom Edition published by ACADEMIC PRESS, INC. (LONDON) LTD. 24/28 Oval Road. London NW1 Library of Congress Cataloging in Publication Data Ranganathan, Darshan. Art in biosynthesis. Bibliography: p. Includes indexes. 1. Biosynthesis. 2. Chemistry, Organic. I. Ranganathan, Subramania, joint author. II. Title. QH345.R36 574.l'929 76-4108 ISBN 0-12-580001-0 PRINTED IN THE UNITED STATES OF AMERICA This Work Is Dedicated to the Cause of A Greater Awareness of Nature by Man, with Fond Hopes for a Deeper Appreciation of Her Presence in Our Midst and an Increased Desire to Simulate Her Experience in Building Molecular Frameworks Preface Art in Biosynthesis projects Nature as an organic chemist supreme, and presents representative examples whose biosynthetic pathways are known on the basis of experimentation. Art in Bio- synthesis, like the earlier Art in Organic Synthesis pays tribute to the creativity associated with the construction of molecular frameworks. The style of presentation of this book is similar to that of Art in Organic Synthesis to enable a quick comparison of the specific synthetic strategies. Such a comparison cannot but profoundly influence us and lead the art of organic synthesis in a direction dictated by Nature, which would indeed be most desirable. Simple in her means but inexhaustively rich in imagination and application, Nature operates more deftly whereas man's conquests with his vast armory of reagents and an infinite choice of reaction conditions, although awe inspiring and vastly impressive, cannot create that gentle glow of utter fascination. There is no need for us to regret our inadequacies. Nature has been building carbon frameworks for the past five billion years, and has been producing the necessarily highly sophisticated assemblies incorporating the genetic apparatus for nearly three billion years. Comparatively, man's experience as a creator of molecular frameworks is nascent and herein lies our relative lack of versatility and astuteness in planning. For example, Nature produces nearly 1000 indole alkaloids with just two building blocks, namely, tryptophan and loganin! The chemical simulation of biological processes is an endeavor that has captured the imagination of the organic chemists in recent times. This book is intended to promote this highly desirable transition. The largely pictorial presentations are followed by, in addition to the author index and subject index, a glossary, and α-amino acid index, a reagent index and reaction-type index to enable ready retrieval of information. In a large number of cases, biological reaction mechanisms are interpreted on the basis of in vitro experience. These are provided by us to maintain continuity and to emphasize the fact that biological transformations strictly follow the laws of bond-forming and bond-breaking that have been deduced from experience with in vitro systems. We would like to express our deep sense of gratitude to Sir Derek Barton for his encouragement and patronage, which has, time and again—buffeted as we are with the ever present perturbations- helped us to align ourselves firmly to academic goals. We express our sincere indebtedness to Professor M.V. George of our department for his ever available encouragement, patronage, indul- gence, and understanding. It is with great pleasure that we acknowledge our gratitude and indebtedness to Mr. Nihal Ahmad IX PREFACE and Mr. D.S. Panesar who are entirely responsible for the production of this manuscript. These colleagues took as much pride in the book as ourselves and their exemplary dedication to the arduous task was to us a great encouragement. We thank Mr. V.A. Narayan for his meticulous compilation of the author index. We are most grateful to Academic Press, for their interest in the work, which was mainly responsi- ble for the rapid progress of the book. Darshan Ranganathan Subramania Ranganathan x Foreword Organic chemists have always been interested in the biosynthesis of natural products. At first, the main purpose of biosynthetic theory was to aid in the deduction of structure. At a time when structural determination was very difficult, the aid of a biosynthetic hypothesis could be invaluable. Robinson's derivation of the structure of morphine is a pertinent example. Much, however, has changed in organic chemistry in the last 30 years. First, thanks to physical techniques, especially X-ray crystallography, the determination of structure has become a trivial matter. Second, thanks to radioactive labeling, it is now possible to confirm, or to disprove, a biosynthetic hypothesis. Indeed, in favorable cases, every sequential step in a long biosynthetic sequence can be elucidated. Of course, not all cases are favorable, because of difficulties of transfer of metabolites through cell walls. However, much has been accomplished, especially with plants and with microorganisms. Once a biosynthetic sequence has been determined, it can be compared with biosynthetic hypothesis. It is indeed gratifying when the two are in agreement and when hypothesis can be used to make yet further, verifiable, predictions. An established biosynthetic sequence is a challenge to the synthetic organic chemist to imitate and to equal Nature. Imitation is, in many cases possible, but we are far from equaling Nature in the yield and stereospecificity of her processes. Art in Biosynthesis is a work of appreciation and criticism of the beauty of biosynthetic processes and of the interaction between man (the organic chemist) and Nature. It contains numerous well- chosen examples and will be of value as a source book, as an inspiration to research, and even more perhaps, as an aesthetic work of appreciation. The two authors are, by ability and background, specially gifted to write such a book. I am sure that this work will be very well received by chemists and biochemists. Sir Derek Barton, D.Sc., FRS, No bei Laureate Hof mann Professor of Organic Chemistry imperial College of Science and Technology London xi AJMALICINE Π ΓΤ H* The synthesis of AJmalicine from vincoside is an excellent illustration of Nature's subtle art of changing carbon frame- works by fewj entirely rational transformations. -\ hydrolysis 1- OGIu Me0 C 2 Vincoside(see p.178) hemiketal opening 1 AJMALICINE Michael addition! -Γ cyclisation J ^ [reduction J A. R. Battersby, Pure and Appl. Chem., 14, 117 (1967)5 A. R. Battersby, R. S. Kapil, J· A. Martin and L. Mo; Chem. Comm., 133 (1968); P. Loew and D. Arigoni, Chem.Comm.,, I37 (I968); A. R. Battersby, A. R. Burnett and P.G. Parsons, Chem. Comm., I28O (1968); A. I. Scott, Ace. Chem. Res., 3_ 151 (1970); A. I. Scott, Bioorg. Chem., _3, 398 (197^). 2 AMMONIA NH 3 The biosynthesis of ammonia - nitrogen fixation - is next 3 to photosynthesis the most important operation that is associa- 3 ted with life. Nearly all the nitrogen needed for growth is provided from biosynthesis with chemical fertilisers playing a minor role. The transformation of nitrogen to ammonia is a difficult process and jm vitro is accomplished by hydrogénation at high temperatures and pressures. Yet^ in Nature the same net reaction is achieved under ambient conditions! It was only in the last decade after an intensive effort the salient y 5 aspects of Nature's fascinating fnitrogen-fixing! system became understood leading to intense current efforts to simulate the p biological nitrogen fixation. Mo containing / M o - N = N —[ AT P }- Enzyme (Mo - E) II ΙΠ 1. 6 Fe 6 Fe Mo— N = N (ferredoxin) L 16H4 Activated Nitrogen complex Mo-E ♦ 2NH 3 3
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