This edition has been extensively revised and enlarged to take account of recent developments. It emphasises the basic principles of the subject which remain essentially unchanged. The first ten chapters lay the ground work for carbon-carbon bond formation, functional group transformations, etc. with detailed additions which reflect new work. The remaining chapters on boron, phosphorus and silicon reagents, and selected syntheses have undergone extensive revisions. Chapters on selenium reagents and asymmetric synethesis are completely new.