Enantioselective Mannich-Type Reaction of N-Sulfonyl Imines

Significance

The addition of enol ethers to imines is an important method to prepare β-amino carbonyl compounds. The air-stable [Fersulphos×CuBr]₂ dimer complex was used in the presence of a AgClO₄ Lewis acid to achieve the enantio­selective addition of thioester or ester derivatives. The bulky t-Bu-thioester showed better selectivity than the parent methyl ester (91% vs 80% ee, respectively). The aryl or heteroaryl substituent on the sulfonyl moiety influenced greatly both the reactivity and selectivity of the reaction, with a thienyl group showing the best results.