Book excerpt: The guiding principle underlying the subject matter specifically compiled in Volume 5 has been to make available to the organic chemical community a sourcebook comprehensively covering all the important &pgr;-bond-dependent transformations. Thermal, photochemical, and metal-catalyzed cycloadditions of every major type are expertly detailed by the most knowledgeable researchers in these areas. The synthetically useful electrocyclic and sigmatropic processes where alkenic centers are intimately involved in the structural change are similarly canvassed in compact detail. With added attention given to ene reactions, small-ring rearrangements, and related transition metal-associated reactions, coverage has been achieved of the full range of organic transformations directly involving the rebonding of alkenic centers. As a consequence, this volume should serve as the comprehensive sourcebook of the field for the next decade and beyond.