Catalytic [2+2] and [3+2] cycloaddition reactions of allenoates with cyclic ketimines

Cyclic ketimines as electrophiles for [2 + 2] and [3 + 2] cycloaddition reactions of allenoates have been developed, affording functionalized sultam-fused azetidines and dihydropyrroles, respectively, in good yields with high regioselectivities.