Enantioselective Construction and Transformations of Poly­functionalized 3,4-Dihydro-2H-thiopyrano[2,3-b]quinolines

Abstract

We developed an enantioselective organocascade Michael/Henry reaction in the presence of a bifunctional organocatalyst to construct chiral polyfunctionalized 3,4-dihydro-2H-thiopyrano[2,3-b]quinolines. The resulting optically active products with three contiguous stereocenters, one quaternary and two tertiary, were obtained in moderate to good yields and with good to excellent enantioselectivities. Remarkably, the resulting products were readily converted into polyfunctionalized optically active furo[2′,3′:4,5]thiopyrano[2,3-b]quinoline, 3,4-dihydro-2H-thiopyrano[2,3-b]quinoline 1-oxide and 2,3-dihydro-4H-thiopyrano[2,3-b]quinolin-4-one derivatives.