A Novel Bis-Thiourea Organocatalyst for the Asymmetric Aza-Henry Reaction.

A novel bis-thiourea BINAM-based catalyst for the asymmetric aza-Henry reaction has been developed. This catalyst promotes the reaction of N-Boc imines with nitroalkanes to afford β-nitroamines with good yields and high enantioselectivities. This catalyst has the advantage that it can be prepared in a single step from commercially available materials. A model is proposed for the catalyst action where the both components of the reaction are activated simultaneously by hydrogen bonding. Regardless of the mechanism, the success of the present catalyst demonstrates the potential of bis-thioureas as an interesting class of relatively unexplored catalysts.