Macrocyclic Polyether Syntheses

It seems likely that no project of this magnitude is undertaken in the absence of several motivations. This book is no exception. There are, from our perspective, at least two rational reasons for conducting this cataloging and organizational effort. The first of these is the obvious fact that a very large number of macrocyclic polyethers have now been prepared and nowhere is there a comprehensive listing of them. A number of excellent reviews have been published dealing with one or more aspects of macrocycle chemistry, but we felt a great need for a single source listing known compounds. We have, the- fore, attempted to provide such a listing to assist ourselves in keeping track as well as, we hope, helping others in this field. We also felt that there was a need for a survey of methods which have been utilized in the syntheses of these cation binders so that the novice could establish some starting point. Wherever possible, we have also attempted to point to the motivations which en gendered the various syntheses. The somewhat irrational reason which propelled us into this endeavor was the ques tioning of Charlie Morgan who often asked if one or another obscure compound had been synthesized. As often as not, we were uncertain arid now at least have a reference which, if not absolutely complete, will at least save face.

It seems likely that no project of this magnitude is undertaken in the absence of several motivations. This book is no exception. There are, from our perspective, at least two rational reasons for conducting this cataloging and organizational effort. The first of these is the obvious fact that a very large number of macrocyclic polyethers have now been prepared and nowhere is there a comprehensive listing of them. A number of excellent reviews have been published dealing with one or more aspects of macrocycle chemistry, but we felt a great need for a single source listing known compounds. We have, the- fore, attempted to provide such a listing to assist ourselves in keeping track as well as, we hope, helping others in this field. We also felt that there was a need for a survey of methods which have been utilized in the syntheses of these cation binders so that the novice could establish some starting point. Wherever possible, we have also attempted to point to the motivations which en gendered the various syntheses. The somewhat irrational reason which propelled us into this endeavor was the ques tioning of Charlie Morgan who often asked if one or another obscure compound had been synthesized. As often as not, we were uncertain arid now at least have a reference which, if not absolutely complete, will at least save face.

Synthetic Multidentate Macrocyclic Compounds attempts to bring together selected chapters in which the authors discuss in depth investigations in important areas of macrocycle research. The chapters deal mainly with macrocyclic compounds (saturated polyethers and their derivatives), and macrobicyclic compounds (cryptates). The book contains six chapters and opens with a first-hand account of the initial synthesis of the cyclic polyethers. This is followed by separate chapters on the synthesis of cyclic polyethers, polyether amines, and polyether sulfides; the synthesis of multidentate compounds; and the structure of synthetic macrocyclic compounds and their cation complexes. Subsequent chapters deal with the rates of reactions and the mechanism by which synthetic macrocyclic ligands complex substrates in solution; and commercial applications of the synthetic macrocyclic ligands. This book is primarily aimed at researchers and students in organic, physical, analytical, and inorganic chemistry, and in chemical engineering. However, it will also be of interest to many in the areas of biology, biochemistry, and physiology. Extensive literature references are found in each chapter.

The scientific and practical interest in coronands (crown ethers), cryptands, podands as complexing agents for cations as well as for anions and neutral low molecular species is undeniable 1,2). The chemistry of crown compounds is steadily increasing. About 250 original papers dealing with crown chemistry appeared only in 1980. New molecules· with crown ether properties are constantly synthesized and new applications discov,?red. Owing to lack of space, only a small number of the original publications is men tioned here. Thus, in the literature compilation only some, but relevant works are selected for each chapter. Whenever possible, reference is made to reviews or review-like articles alone by means of which origin,al works can be consulted. The reviews given under ref. 1) are considered to be the most relevant. The formulae presented in the figures should be understood as representative structures outlining a specific field. 2 Classification of Oligo-/Multidentate Neutral Ligands and of their Complexes Today, a distinction is made between the classical ring oligoethers (crown ethers) and monocyclic coronands, oligocyclic spherical cryptands and the acyclic podands with respect to topological aspects 3). This classification and the topology are illustrated in Fig. 1, each figure representing the minimum number of donor atoms and chain segments characteristic of each class of compounds. Multidentate mono cyclic ligands with any type of donor atoms are called coronands ("crown compounds"), while the term crown ether should be reserved for cyclic oligoethers exclusively containing oxygen as donor atom.