Efficient One-Pot Synthesis of Spirooxindole Derivatives Containing 1,4-Dihydropyridine-Fused-1,3-Diazaheterocycle Fragments via Four-Component Reaction

An efficient, one-pot synthetic protocol toward spirooxindole derivatives containing 1,4-dihydropyridine-fused 1,3-diaza-heterocycle fragments, a class of biologically active compounds starting from 1,1-bis(methylthio)-2-nitroethylene, 1, n-diamine, isatin, or its derivatives, and malononitrile is described. The reaction proceeds in ethanol in the presence of 10 mol% of piperidine as a basic catalyst under reflux conditions to produce the title compounds in 74-85% yields.