Synthesis of Azacarbocycles via Hydroamination and Aminocarbonylation

Significance

Reported is the synthesis of pyrrolidines 2 and six-membered azacarbocycles 4 via the metal-free intramolecular hydroamination of alkenyl hydrazides 1 and 3 under conventional or microwave heating conditions. Alkyl substitution is tolerated on the alkene, although higher temperatures are usually required for efficient cyclization. In contrast, carbazates and semicarbazides 5 undergo aminocarbonylation to give bicyclic products 6. This reaction proceeds in a stereospecific syn addition fashion, consistent with formation of an aminoisocyanate intermediate and subsequent cycloaddition.