Crown Ethers and Analogs Edited by Saul Patai and Zvi Rappoport Copyright 0 1989 by John Wiley & Sons Ltd Crown ethers and analogs THE CHEMISTRY OF FUNCTIONAL GROUPS A series of advanced treatises under the general editorship of Professor Saul Patai The chemistry of alkenes (2 volumes) The chemistry of the carbonyl group (2 volumes) The chemistry of the ether linkage The chemistry of the amino group The chemistry of the nitro and nitroso groups (2 parts) The chemistry of carboxylic acids and esters The chemistry of the carbon-nitrogen double bond The chemistry of amides The chemistry of the cyano group The chemistry of the hydroxyl group (2 parts) The chemistry of the azido group The chemistry of acyl halides The chemistry of the carbon-halogen bond (2 parts) The chemistry of the quinonoid compounds (2 volumes, 4 parts) The chemistry of the thiol group (2 parts) The chemistry of the hydrazo, azo and azoxy groups (2 parts) The chemistry of amidines and imidates The chemistry of cyanates and their thio derivatives (2 parts) The chemistry of diazonium and diazo groups (2 parts) The chemistry of the carbon-carbon triple bond (2 parts) The chemistry of ketenes, allenes and related compounds (2 parts) The Chemistry of the sulphonium group (2 volumes) Supplement A: The chemistry of double-bonded functional groups (2 parts) Supplement B: The chemistry of acid derivatives (2 parts) Supplement C: The chemistry of triple-bonded functional groups (2 parts) Supplement D: The chemistry of halides, pseudo-halides and azides (2 parts) Supplement E: The chemistry of ethers, crown ethers, hydroxyl groups and their sulphur analogues (2 parts) Supplement F: The chemistry of amino, nitroso and nitro compounds and their derivatives (2 parts) The chemistry of the metal-carbon bond (4 volumes) The chemistry of peroxides The chemistry of organic selenium and tellurium compounds (2 volumes) The chemistry of the cyclopropyl group (2 parts) The chemistry of sulphones and sulphoxides The chemistry of organic silicon compounds (2 parts) Updates The chemistry of a-haloketones, a-haloaldehydes and a-haloimines Nitrones, nitronates and nitroxides Crown ethers and analogs The formation of carbon-halogen bonds (in press) Crown ethers and analogs EDW IN WEBER University of Bonn JOHNL . TONER Kodak Research, New York ISRAELG OLDBERC Tel Aviv University FRITZV OGTLE University of Bonn DALEA . LAIDLER ICI, Runcorn, Cheshire J. FRASERST ODDART University of Sheffield RICHARDA . BARTSCH Texas Technical University CHARLELS. LIOTTA Georgia Institute of Technology Edited by SAULP ATAaI nd Zvr RAPPOPORT The Hebrew University of Jerusalem Updates from the Chemistry of Functional Groups 1989 JOHN WILEY & SONS CHICHESTER.NEW YORK.BRISBANE.TORONTO.SINGAPORE An Intersciences Publication Copyright 0 1989 by John Wiley & Sons Ltd. All rights reserved. No part of this book may be reproduced by any means, or transmitted, or translated into a machine language without the written permission of the publisher Library of Congress Cataloging-in-Publication Data: Crown ethers and analogs (Updates from the Chemistry of the functional groups) 'An Interscience publication.' I . Ethers. I. Weber, Edwin. 11. Patai, Saul. 111. Rappoport, Zvi. IV. Series. QD305.E7C76 1989 547.035 87-25350 ISBN 0 471 91707 9 British Library Cataloguing in Pubkcation Data: Crown ethers and analogs-(Updates from the chemistry of functional groups). I . Ethers 2. Cyclic compounds I. Weber, Edwin 11 Patai, Saul 111. Rappoport, Zvi IV. Series 547'.035 QD341.E7 ISBN 0 471 91707 9 Phototypesetting by Thomson Press (India) Ltd, New Delhi Printed in Great Britain at The Bath Press, Avon List of contributors R. A. Bartsch Department of Chemistry and Biochemistry, Texas Technical University, Box 4260, Lubbock, Texas 79409, USA. I. Goldberg School of Chemistry, Tel Aviv University, Ramat Aviv 69978 Tel Aviv, Israel. D. A. Laidler New Business Planning Group, ICI plc, P.O. Box 11, The Heath, Runcorn, Cheshire WA7 4QE, UK. C. L. Liotta School of Chemistry, Georgia Institute of Technology, Atlanta, Georgia 30332, USA. J. F. Stoddart Department of Chemistry, University of Shefield, Shefield S3 7HF, UK. J. L. Toner Exploratory Sciences Division, Life Science Research Labora- tories, Eastman Kodak Company, Kodak Park, Rochester, New York 14650, USA. F. Vogtle Institut fur Organische Chemie und Biochemie der Universitat, Gerhard-Domagk-Strasse 1, D-5300 Bonn 1, RFG. E. Weber Institut fur Organische Chemie und Biochemie der Universitat, Gerhard-Domagk-Strasse 1, D-5300 Bonn 1, FRG. Foreword This is the third volume published in the new series entitled ‘Updates from the Chemistry of the Functional Groups’. The main volume on The ether linkage in the Functional Groups series appeared in 1967. This book did not even mention crown ethers, while Sgppfement E which appeared in 1980 already contained three full chapters (a total 174 pages) on crown ethers, while a fourth chapter also dealt mainly with the structural aspects of the same class of compounds. Now, less than ten years after the appearance of Supplement E , the present volume again contains a very substantial part describing material which was unknown or a t least unpublished ten years ago. Indeed, the four updated chapters in the present volume deal not only with new material in the field of crown ethers, but with a variety of analogous types of compounds which were developed and for which important new uses were found only recently. Chapters 1,2,4 and 6 were originally published in Supplement E (1980), while Chapter 8 is reprinted from Supplement C (1983). Chapters 7 and 9 are essentially updates of some of the reprinted chapters although they too contain much novel material. Chapter 5 is almost wholly devoted to new types of complexes and, finally, Chapter 3 is a review emphasizing modern methods of molecular modelling as applied to host-guest chemistry. As always, the editors will be grateful to readers who would call their attention to mistakes or omissions in this volume as well as in other volumes of the series. SAUL PATAI ZVI RAPPOPORT JERUSALEM March 1989 vii Contents Synthesis of crown ethers and analogues 1 D. A. Laidler and J. F. Stoddart Organic transformations mediated by macrocyclic multidentate ligands 59 C. L. Liotta Modern aspects of host-guest chemistry: molecular modeling and conform- ationally restricted hosts 11 J. L. Toner Crown ethers-complexes and selectivity 201 F. Vogtle and E. Weber New developments in crown ether chemistry: lariat, spherand and second- sphere complexes 305 E. Weber Geometry of the ether, sulphide and hydroxyl groups and structural chemistry of macrocyclic and non-cyclic polyether compounds 35 9 I. Goldberg Structural chemistry of crown ethers 399 1. Goldberg Complexation of aryldiazonium ions by polyethers 477 R. A. Bartsch Appendix to complexation of aryldiazonium ions by polyethers 505 R. A. Bartsch Author index 519 Subject index 549 ix Crown Ethers and Analogs Edited by Saul Patai and Zvi Rappoport Copyright 0 1989 by John Wiley & Sons Ltd CHAPTER 1 Synthesis of crown ethers and analogues DALE A. LAIDLER and J. FRASER STODDART New Business Planning Group, ICI pic, Runcorn, England and University of Sheffield, England I. HISTORICAL BACKGROUND . . 2 11. FACTORS INFLUENCING YIELDS IN SYNTHESIS . . 3 A. The Template Effect . . 3 B. The Gauche Effect . . 9 C. Other Effects , . 1s 111. DESIGN AND STRATEGY . * 15 IV. SYNTHESES EXEMPLIFIED . * 16 A. Monocyclic Multidentate Ligands . * 16 1. All-oxygen systems . . 17 2. All-nitrogen systems. . . 19 3. All-sulphur systems . . 20 4. Oxygen and nitrogen systems . . 21 5. Oxygen and sulphur systems . . 22 6. Nitrogen and sulphur systems . . 23 7. Oxygen, nitrogen and sulphur systems . . 24 B. Crown Compounds Incorporating Aromatic Residues . . 24 1. Systems fused to benzene rings . . 24 2. Systems fused to furan rings . . 27 3. Systems fused to pyridine rings . . 29 4. Systems fused to thiophene rings . . 30 C. Macrocyclic Diester, Dithioester and Diamide Compounds . 31 D. Crown Compounds Containing Carbonyl Groups . . 34 1. Oxocrownethers . . 34 2. Crown ethers incorporating'p-dikeione re'sidues . 34 E. Crown Compounds Incorporating lmine and Oxime Functions . 36 1. Manocycles from Schiff-base condensations . . 36 2. Oxime linkages in macrocycles . . 38 F. Acyclic Crown Compounds . . 38 G. Macrobicyclic, Macrotricyclic and Macropolycyclic Ligands . 40 1. Systems with nitrogen bridgeheads . . 40 2. Systems with carbon bridgeheads . . 43 3. A system with nitrogen and carbon bridgeheads. . . 43 1 2 Dale A. Laidler and J. Fraser Stoddart H. Chiral Crown Ethers . . 44 1. Meso compounds and racemic modifications . . 44 2. Optically-active crown ethers from natural products . . 47 3. Optically-active crown ethers from resolved precursors. . . 49 V. TOXICITY AND HAZARDS . . 51 VL REFERENCES . . 52 I. HISTORICAL BACKGROUND It is interesting to reflect upon the fact that, although linear compounds containing sequential ether have occupied an important position in chemistry for many years, it is only during the last decade or so that macrocyclic polyethers and their analogues have made their major impact upon the scientific community. Alas, the fascinating complexing properties of macrocyclic polyethers were not antici- pated from the comparatively mundane chemical behaviour of cyclic ethers containing up to seven atoms in their rings4 s5 . Indeed, as often happens in science, serendipity played6 an important role in the discovery of the so-called crown ethers and the appreciation of their somewhat intriguing characteristics. Although the early literature was not devoid of reports on the synthesis of macrocyclic poly- ethers, their value and potential was not realized by those involved. it is easy to feel with hindsight that it should have been; but it is difficult to envisage how it could have been! The first macrocyclic polyethers were reported by Luttringhaus’ in 1937 as part of an investigation of medium- and large-sized rings. For example, he obtained the 20-membered ring compound 1 in low yield after reaction of the monosubstituted resorcinol derivative 2 with potassium carbonate in pentan-1-01. Later, the tetra- furanyl derivative 3 was isolated* after acid-catalysed condensation of furan with acetone and the cyclic tetramers 4 and 5 of ethylene9 and propyleneI0 oxides, respectively, were reported. (1) (4) R = H (5 ) R = Me 1. Synthesis of crown ethers and analogues 3 Several acyclic polyethers, as well as compound (S), were found' t o dissolve small quantities of potassium metal and sodium-potassium alloy giving unstable blue solutions of solvated electrons and solvated cations. However, it was not until 1967 that Pedersen" reported on the formation of stable complexes between macrocyclic polyethers and salts of alkali and alkaline earth metals. During an attempted preparation of the diphenol 6 from the dichloride 7 and the mono- protected catechol derivative 8, the presence of 10% of catechol(9) as an impurity led6 to the isolation (see Scheme 1) of the unexpected by-product which was identified as the macrocyclic polyether 10. Given the trivial name dibenzo-18- crown-6 by Pedersed v 1 z, it was found to be insoluble in methanol by itself, but became readily soluble on the addition of sodium salts. Furthermore, it was obtained in 45% yield when pure catechol (9) was employed6 p 1 in its synthesis. (81 R = (9) R = H (10% present as an impurity) SCHEME 1 This amazingly high yield for a macrocycle obtained on condensation of four molecules raises questions of fundamental importance which will be discussed in Section 11. Following upon his initial discoveries, Pedersen' prepared more than 60 compounds in order to ascertain the optimum ring size and the preferred constitutional arrangement of oxygen atoms in the macrocycles for them to complex with a wide variety of cationic species. Those compounds which contain between five and ten oxygen atoms, each separated from its nearest neighbour by two carbon bridges, were found to be the most effective complexing agents. These observations have led to the synthesis of many crown ethers and analogues. This chapter is devoted to a review of the general principles and fundamental concepts governing this kind of macrocyclic ring formation as well as to a summary of the methodology and reaction types employed in the synthesis of these macrocycles. II. FACTORS INFLUENCING YIELDS IN SYNTHESIS A. The Template Effect The isolation of dibenzo-18-crown-6 (10) in 45% yield under the conditions given in Scheme 1 prompted Pedersen6 to observe that 'the ring-closing step, either by a second molecule of catechol or a second molecule of bis(2-chloroethyl) ether,