Synthesis of Novel Thiazoline Catalysts and Their Application in Michael Addition Reaction

Several novel chiral thiazoline catalysts containing thiazoline, thiourea and proline were efficiently synthesized from commercially available L-cysteine. These ligands were subsequently applied to the asymmetric Michael reaction between cyclohexanone and various β-nitrostyrene. The result shows that the optimal catalyst for this reaction is ligand 18d, the organocatalyst with thiazoline, thiourea and chiral proline motif, which efficiently promotes the enantioselective conjugate addition of cyclohexanone to various nitroalkenes to yield the corresponding addition products in high to excellent yields with enantiomeric excess(e.e.) up to 95% and diastereoselectivity ratio(dr.) up to 99:1.