Reactivity and Structure

Transcription

1 Reactivity and Structure Concepts in Organic Chemistry Volume 6 Editors: Klaus Hafner Charles W Rees Barry M. Trost Jean-Marie Lehn P. von Rague Schleyer Rudolf Zahradnik

2 M L. Bender M. Kamiyama Cyclodextrin Chemistry With 14 Figures and 37 Tables Springer-Verlag Berlin Heidelberg New York 1978

3 Myron L. Bender Professor of Chemistry and Biochemistry Northwestern University Evanston, IL 60201/USA Makoto Komiyama Postdoctoral Research Associate in Chemistry Northwestern University Evanston, IL 60201/USA ISBN-13: e-isbn-13: DO I: / Library of Congress Cataloging in Publication Data. Bender, Myron L Cyclodextrin chemistry. (Reactivity and structure; v. 6) Includes bibliographical references and indexes. 1. Dextrine. 2. Cyclic compounds. I. Komiyama, Makoto, joint author. II. Title. III. Series. QD32I.B ' This work ist subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount of the fee to be determined by agreement with the publisher. by Springer-Verlag Berlin Heidelberg 1978 Softcover reprint of the hardcover 1 st editioo / \0

4 To DR. DoNALD A. SPEER, who made much of the research behind this book possible, and to our wives, MURIEL S. BENDER and MITSUKO KOMIYAMA

5 Preface Chemistry was at one time completely described in terms of collision theory, in which one molecule collided with another, sometimes producing reaction. Then came the realization that enzymes which are highly efficient catalysts, work by way of prior complexation, often stereospecific, which is then followed by chemical reaction. Thus, systems that exhibit "host-guest" relationships, i.e., that show complexing are being looked at an ever increasing frequency. The cyclodextrins are the first and probably the most important example of compounds that exhibits complex formation. This is a book about the cyclodextrins. There are of course other compounds that exhibit "host-guest" relationships and thus bind other organic molecules, but so far they have not achieved the importance of the cyclodextrins. By their name it is obvious that cyclodextrins are cyclic compounds. The complexes that they form are therefore cyclic inclusion complexes. Because the complexes are cyclic in nature, complexation can be very strong, as opposed to 1t-complex, electrostatic, or apolar complexes in which complex formation is two-dimensional rather than three-dimensional. Cyclodextrins turn out to be excellent models of enzymes. This is probably not fortuitous because they were first sought since it was discovered that the principal binding in the enzyme chymotrypsin was a cyclic inclusion complex. Cyclodextrins can do more than form cyclic inclusion complexes, they can catalyze as well. But catalysis always occurs after complex formation. Cyclodextrins can catalyze in a covalent manner after complexation, for then the many hydroxyl groups of the cyclodextrin can act as nucleophiles. Of course it is possible to attach other groups to cyclodextrins which can also act as nucleophiles. In such cases covalent intermediates in which one part of the substrate is attached to the cyclodextrin will be formed. Catalysis can also take the form of non-covalent catalysis in which the inside of these doughnut-shaped molecules acts as a medium of low dielectric constant for reaction to occur or in which the torus of the molecule can preferentially bind one conformer better than another. All these possibilities will be discussed. We should like to thank the large number of people who have worked on cyclodextrins during the past years. We also thank the National Science Foundation and the Hoffmann-LaRoche Co. who have supported research VII

6 Preface in this area for many years. Makoto Komiyama would like to thank his former teacher, Dr. Hidefumi Hirai, and his parents, Mr. and Mrs. Kojiro Komiyama. We both thank Ms. Rosalind Bach who did a superb job in preparing this book for publication. September, 1977 M. L. Bender and M. Komiyama Northwestern University Evanston, Illinois, USA. VIII

7 Contents I. Introduction. II. Properties.. 1. Source and Nomenclature Structure and Physical Properties. III. Inclusion Complex Formation Detection of Complex Formation and Structure of the Complexes The Determination of Dissociation Constants of Inclusion Complexes Binding Force of the Complexes IV. Catalyses by Cyclodextrins Leading to Practical Usages ofcyclodextrins V. Covalent Catalyses Hydrolyses of Phenyl Esters Hydrolyses of Amides Hydrolyses of Organophosphates and Carbonates 46 VI. Noncovalent Catalyses The Microsolvent Effect The Conformational Effect 55 VII. Asymmetric Catalyses by Cyclodextrins Selective Precipitation of D, L Compounds Hydrolyses of Esters Cleavage of Organophosphates Addition and Oxidation Reactions 64 IX

8 Contents VIII. Improvement by Covalent and Noncovalent Modification 1. Acceleration of the Deacylation Step 2. Better Models of Hydrolytic Enzymes 3. Cyc10dextrins Containing Metal Ions IX. Conclusion References.. Author Index Subject Index x