Acyl hydrazines as precursors to acyl radicals

The use of acyl hydrazines (hydrazides) as precursors for the stoichiometric generation of acyl radicals is explored. Two classes of substrates are examined: unsubstituted acyl hydrazines and acyl hydrazines substituted with a leaving group (2-nitrobenzenesulfonyl or ‘nosyl’). Both types are successfully converted to acyl radicals, and are then trapped by nitroxide radicals to give acyloxyamine products. Cyclization reactions are demonstrated for both classes of substrates. A low temperature modification of the McFayden–Stevens reaction is also developed.