Since the introduction of the concept of synthons in 1967, it has become common among practitioners of organic synthesis to treat numerous synthetic reactions as simple combinations of the appropriate synthons instead of writing out the actual reagents in full. This book provides chemists who plan their synthetic routes manually with information on some of the new umpoled synthons and the use of synthons in planning organic syntheses. The major part of the text is devoted to acyl anions, hydroxycarbonyl and related anions, carbonyl (ALPHA)-cations, and carbonyl (BETA)-anions. Another group discussed comprises carbanionic synthons in which the carbon atom carries a singly bonded heteratom. Emphasis is on the aspects relating to synthetic use. This work includes a tabular presentation of known applications, along with relevant data on the sources, auxiliary reagents, yields, and restrictions. More than 2,000 references cited.