Organocatalytic Asymmetric Addition of Aromatic α-Cyanoketones to o-Quinone Methides: Synthesis of 3,4-Dihydrocoumarins and Tetrasubstituted Chromans.

The first organocatalytic asymmetric addition of aromatic α-cyanoketones to in situ-generated o-quinone methides has been developed. The products 3,4-dihydrocoumarin and tetrasubstituted chroman were obtained via addition of aromatic α-cyanoketones to in situ-generated o-quinone methides followed by treatment with 0.7 N HCl. With 10 mol % catalyst, the desired products were obtained in high enantio- and diastereoselectivities.