An efficient construction of N,N-bicyclic pyrazolidinones comprising enaminonitriles via asymmetric [3+2] cycloaddition

The first thiourea catalysed asymmetric [3+2] cycloaddition reaction between azomethine imines and malanonitriles was developed. Using this novel synthetic strategy, hybrid molecules containing N,N-bicyclic pyrazolidinones fused with enaminonitriles were synthesized in good yields with excellent enantioselectivities (up to 98% ee).