Lewis acid-catalyzed hetero Diels–Alder cycloadditions of 3-alkyl, 3-phenyl and 3-carboxylated 2H-azirines

Activation by Lewis acids of 3-alkyl and 3-phenyl 2H-azirines promotes their participation in hetero Diels–Alder reactions with a variety of dienes. This methodology circumvents the previous requirement of an electron-withdrawing carboxyl moiety at the 3-position of the 2H-azirine.