A phosphine-catalyzed novel asymmetric [3+2] cycloaddition of C,N-Cyclic azomethine imines with δ-substituted allenoates.

Catalytic asymmetric [3+2] cycloadditions of C,N-cyclic azomethine imines with δ-substituted allenoates have been developed in the presence of (S)-Me-f-KetalPhos, affording functionalized tetrahydroquinoline frameworks in good yields with high diastereo- and good enantioselectivities under mild condition. The substrate scope has been also examined. This is the first time that δ-substituted allenoates have been applied as a δ,γ-C-C bond participated C2 synthon in asymmetric synthesis.