Aqueous NH3-mediated syntheses of 2-styrylquinoline-4-carboxamides by domino ring opening cyclization strategy

A straightforward and efficient protocol for the synthesis of medicinally relevant 2-styrylquinoline-4-carboxamide has been developed by aqueous ammonia-mediated domino ring-opening and cyclization strategy of 3-hydroxyoxindole. The starting precursors 3-hydroxyoxindoles were easily prepared through organocatalytic “on water” reaction of isatin and benzalacetone in high yields. The wide substrate scope with operationally simple experimental procedures provides an opportunity to create library of 2-styrylquinoline-4-carboxamide derivatives.