Chiral C2 -symmetric bis-thioureas as enzyme mimics in enantioselective Michael addition.

We report herein the synthesis and application of enantiopure C2 -symmetric primary amine-1,3-bis-thiourea organocatalysts in enantioselective conjugate 1,4-Michael addition of carbonyl containing nucleophiles, to nitroalkenes and N-phenylmaleimide, leading to final products in good enantioselectivities (up to 99%) and yields (up to 99%). We propose supramolecular noncovalent interactions within the organocatalyst's cleft between the substrate and the catalyst, via hydrogen bonding. Supramolecular interaction thus lowers the transition state energy mimicking an enzyme. Mechanism underlying our experimental results is supported by theorical calculations.

C2 -symmetric sulfonamides as homogeneous and heterogeneous organocatalysts that mimic enzymes in enantioselective Michael additions.

Herein, we report the synthesis of C2 -symmetric sulfonamides as homogeneous and heterogeneous organocatalysts and their application in the enantioselective conjugate 1,4-Michael addition of carbonylic nucleophiles to ß-nitrostyrene. Organocatalysts hydrogen bond to ß-nitrostyrene and enamine in the transition state, mimicking an enzyme leading to final products in high yields (up to 98%) and good enantioselectivities (up to 96%). In addition, these results were supported by density functional calculations.