Homochiral l-prolinamido-sulfonamides and their use as organocatalysts in aldol reactions

Abstract The synthesis of new homochiral l -prolinamido-sulfonamides 1 – 7 from enantiomerically pure ( R , R )-11,12-diamino-9,10-dihydro-9,10-ethanoanthracene ( R , R )- 8 is reported. The l -prolinamido-sulfonamides 1 – 7 were tested as organocatalysts (10 mol %) in the aldol reaction of p - nitrobenzaldehyde and acetone in dichloromethane at room temperature in the presence of water (1 equiv) and acetic acid (20 mol %) giving good to high yields and enantioselectivities. Catalyst 4 (10 mol %) afforded the best results in the aldol reaction of acetone with p -substituted-benzaldehydes with electron withdrawing groups (i.e., nitro, cyano, bromo and chloro, up to 97% yield and 90% ee). The origin of the enantioselective induction was modeled using DFT methods. The estimated enantioselectivity for the model system is consistent with the experimental data.