Palladium-catalyzed aza-Wacker cyclization of O-homoallyl benzimidates: expeditious access to heteroatom-rich substituted 1,3-oxazines via alkene trifunctionalization

A palladium-catalyzed aza-Wacker cyclization of O-homoallyl benzimidates has been developed to afford a variety of useful 4-methylene-1,3-oxazine building blocks in moderate to good yields. The synthetic utility of the 4-methylene-1,3-oxazines is illustrated by the conversion of the exo C - C bond to a diverse collection of heteroatom-rich moieties through subsequent electrophilic addition enabling C-I, C-Br, C-Cl, C-O, C-N, and C-C bond formations. These tandem protocols scale well, and their products are demonstrated to be valuable frameworks for use in medicinal and biological chemistry.