Organic Syntheses consists of protocols for the synthesis of useful chemical compounds. Each protocol is repeated in the laboratory of one of the editorial board members for accuracy or for missing experimental details prior to publication. For each protocol, safety warnings are presented along with detailed experimental descriptions for the preparation, purification, and identification of the compound. Additionally, special reaction conditions are detailed, along with the source of reagents, waste disposal information, a discussion of the results, references to the primary literature, and an appendix of nomenclature and registry numbers. Continuing the tradition of providing significant and interesting procedures, Organic Syntheses, Collective Volume X is a compilation of revised editions of Annual Volumes 75 through 79. Following precedent, there is no specific or central theme to this volume, but the procedures can be organized into four main categories: (1) asymmetric syntheses, chiral auxiliaries, and chiral ligands; (2) reactions that are promoted by metals or proceed via organometallic intermediates; (3) cycloaddition reactions; (4) valuable synthetic transformations and building blocks.