TBAB-catalyzed cascade reactions: facile synthesis of 1-trifluoromethyl-3-alkylidene-1,3-dihydrofuro[3,4-b]quinolines via 5-exo-dig cyclization of o-arylalkynylquinoline aldehydes

Abstract

A convenient method for the facile synthesis of 1-trifluoromethyl-3-alkylidene-1,3-dihydrofuro[3,4-b]quinolines was developed from the TBAB-catalyzed nucleophilic addition/cyclization reaction of o-arylalkynylquinoline aldehydes with trimethyl trifluoromethyl silane, cesium fluoride, and water; the product was obtained in good to excellent yields. The reaction proceeded smoothly via 5-exo-dig selectivity and anti co-planarity addition, affording Z-selective products in an aerobic atmosphere at room temperature. The dihydrofuroquinoline derivatives formed are structurally related to the well-known furoquinoline alkaloids of the rutaceae family.