From the reviews of the previous editions: ∗ "For completeness, the authors . . . include protective groups and techniques for formation and cleavage that are seldom used as well as those that are more common. . . . Anyone who does organic synthesis must have convenient access to this book." –Journal of the American Chemical Society. ∗ "Essential to the modern synthetic organic chemist . . . should be in the libraries of all academic, governmental, and industrial organizations concerned with organic synthesis." –Polymer News. Reflecting the latest advances in protective group methodology, this Third Edition of the proven laboratory reference is expanded by more than 50%, providing readers with a comprehensive compendium of 1,050 of the most useful protective groups as well as 5,350 references to original publications. Protective groups are organized by six major organic functional groups: hydroxyl, amino, carboxyl, carbonyl, sulfhydryl, and phosphate groups (the last new to this edition). Also added in this edition are protection of the alkyne–CH, expanded coverage of protection of all groups, and many new enzymatic methods of protection and deprotection. Each chapter briefly describes the classes of available protective groups, followed by an in–depth look at the chemistry of individual protective groups, their properties, and the best methods of formation and cleavage. Ten reactivity charts with more than 28,000 entries summarize the relative reactivities of 270 commonly used protective groups with 108 reagents. This book will be an indispensable reference for synthetic chemists and students.