A Bifunctional B,N-Based Asymmetric Catalytic Nitrostyrene-Michael Addition Acting through a 10-Membered Ring Cyclic Transition State

The B,N-bifunctional catalyst homoboroproline has been applied to a catalytic asymmetric nitroalkene-Michael addition to beta-nitrostyrene analogues, showing broad substrate tolerance, high conversions and moderate to good asymmetric induction. The ability of homoboroproline to act as an efficient catalyst based on enamine-formation of the secondary amine, coupled with intramolecular Lewis-acid chelation of the nitro function, in a non-FLP manner, to effect efficient and enantioselective catalysis via a proposed large 10-membered ring transition state is remarkable and reinforced by theoretical calculations.

Automated summary

The B,N-bifunctional catalyst homoboroproline has been successfully applied to catalytic asymmetric nitroalkene-Michael addition reactions with beta-nitrostyrene analogues, showing broad substrate tolerance, high conversions, and moderate to good asymmetric induction. The catalyst's efficiency is attributed to enamine formation of the secondary amine and intramolecular Lewis-acid chelation of the nitro function, leading to efficient and enantioselective catalysis through a proposed large 10-membered ring transition state, as supported by theoretical calculations.