Organocatalytic One-Pot Synthesis of Chiral Thiochromenes

Significance

Here the authors report an enantio­selective tandem-Michael-aldol reaction between α,β-unsaturated aldehydes and thiophenol aldehydes leading to an efficient synthesis of chiral thiochromenes. (S)-Pyrrolidine silyl ether 1 in combination with PhCO₂H has been found to be effective for the reaction. With 10 mol% of catalyst 1 good to high yields (72-97%) and enantioselectivities (er = 93:7 to 98:2) are obtained for different aromatic and aliphatic α,β-unsaturated aldehydes.