ChemInform Abstract: Asymmetric Synthesis of Dihydrocoumarins Containing Contiguous Quaternary and Tertiary Stereogenic Centers Catalyzed by a Cinchona‐Alkaloid‐Based Bifunctional Thiourea Derivative.

Abstract

A series of enantiomerically enriched 3,4-dihydrocoumarins containing contiguous quaternary and tertiary stereogenic centers has been efficiently constructed via domino asymmetric Michael addition/transesterification reactions of azlactones with o-hydroxychalcones using a quinine-derived thiourea as bifunctional organocatalyst. Under mild reaction conditions, the optically active 3,4-dihydrocoumarins were generally obtained in 63–96% yields with >20:1 dr and 81–96% ee.