Enantioselective construction of 2,3-dihydrofuro[2,3-b]quinolines through supramolecular hydrogen bonding interactions.

Abstract

The first asymmetric synthesis of 2,3-dihydrofuro[2,3-b]quinolines has been achieved by a cascade asymmetric aziridination/intramolecular ring-opening process of differently substituted 3-alkenylquinolones. Good yields and high enantioselectivities (up to 78% yield and 95% ee) were recorded when employing 2,2,2-trichloroethoxysulfonamide as the nitrene source, PhI(OCOtBu)2 as the oxidant, and a chiral C2 -symmetric Rh(II) complex as the catalyst (1 mol%). The catalyst bears two lactam motifs, which serve as binding sites for substrate coordination through supramolecular hydrogen-bonding interactions.