Synthesis of 3-alkylidene-1,2,3,5,6,7-hexahydro-4H-indol-4-one derivatives in the THF-H2O system

The reactions of dibenzoylacetylene with cyclic enaminocarbonyls in the THF-H2O system lead to 3-alkylidene-1,2,3,5,6,7-hexahydro-4H-indol-4-one derivatives in high yields.