Fe-BPsalan complex-catalyzed asymmetric 1,3-dipolar [3 + 2] cycloaddition reaction of N,N′-cyclic azomethine imines with α,β-unsaturated acyl imidazoles

Abstract

An efficient iron-catalyzed asymmetric 1,3-dipolar cycloaddition of N,N′-cyclic azomethine imines with α,β-unsaturated acyl imidazoles was developed to afford N,N′-bicyclic pyrazolidine derivatives bearing three contiguous tertiary stereocenters (32 examples) in moderate to good yields (up to 97%) and excellent stereoselectivities (up to >25 : 1 dr and 98% ee). The reaction was easily scaled up with high efficiency and excellent selectivities.