A facile and convenient way to functionalized trifluoromethylated spirocyclic[indole-3,4-pyrano[2,3-c]pyrazole] derivatives

An efficient and consecutive one-pot, two-step, four-component reaction for the synthesis of trifluoromethylated spirocyclic[indole-3,4-pyrano[2,3-c]pyrazole] derivatives by the reaction of isatin, malononitrile, ethyl cyanoacetate, or cyanoacetamide, ethyl 4,4,4-trifluoroacetoacetate and hydrazine in the presence of a catalytic amount of piperidine in good yields was described. The structures of new compounds were determined by spectroscopic methods, microanalysis, and X-ray diffraction analysis. In addition, a possible mechanism of the reaction was proposed herein.