Simple Three-Component Method for the Synthesis of Spiroindeno[1,2-b]pyrido[2,3-d]pyrimidine-5,3′-indolines

An efficient, simple, and catalyst-free synthesis of spiroindeno[1,2-b]pyrido[2,3-d]pyrimidine-5,3'-indolines and spiroacenaphthylene-1,4'-indeno-1,5'-pyrido[2,3-d]pyrimidines by the three-component reaction of 1,3-indandione, amino uracils and isatins or acenaphthylene-1,2-dione in refluxing ethanol is reported.