A Bronsted acid catalyst for the enantioselective protonation reaction

A highly reactive and robust chiral Bronsted acid catalyst, chiral N-triflyl thiophosphoramide, was developed, The first metal-free Bronsted acid catalyzed enantioselective protonation reaction of silyl enol ethers was demonstrated using this chiral Bronsted acid catalyst. The catalyst loading could be reduced to 0.05 mol % without any deleterious effect on the enantioselectivity.