Visible-Light-Induced Siloxycarbene Addition to N═N of Azodicarboxylates: Synthesis of Acyl Hydrazides from Acylsilanes.

We report the synthesis of acyl hydrazides from acylsilanes in the presence of visible light without the aid of additives or transition metals. Acylsilanes underwent [1,2]-Brook rearrangement to generate the nucleophilic siloxycarbenes which on further addition to N═N of azodicarboxylates produced the acyl hydrazides. Control experiments indicate that the reaction proceeds through the singlet carbene intermediate. Transformation of the acyl hydrazide functionality to other functional groups was demonstrated, including the synthesis of the drug candidate Moclobemide.