Highly Diastereo- and Enantioselective Formal [4 + 2] Cyclization of Nitroalkenes and Unsaturated Ketoesters under Phase-Transfer Catalysis

A highly diastereo- and enantioselective formal [4 + 2] cyclization of α,β-unsaturated ketoesters with nitroalkenes through a tandem asymmetric Michael addition–intramolecular Henry reaction under dihydroquinine-based phase-transfer catalysis, leading to a one-pot construction of four contiguous stereochemical centers and multiple functional groups with excellent diastereo- and enantioselectivities in high yields, has been developed. The ee values of some products were increased to ∼100% in good yields after one crystallization.