Lewis Acid Catalyzed Annulation of Nitrones with Oxiranes, Aziridines, and Thiiranes

A highly
selective Lewis acid catalyzed annulation of three-membered
heterocycles with nitrones has been developed. Oxiranes, aziridines,
and thiiranes were used as substrates for the synthesis of various
six-membered heterocycles using Al or In catalysts. This catalytic
protocol demonstrates a broad substrate scope and provides access
to new structural motifs in high yields and in excellent selectivity
under mild reaction conditions.