Microwave-Assisted Synthesis of Substituted Pyrazoles and Pyrazolo [3, 4-d]thiopyrimidines

Ethyl(ethoxymethylene)cyanoacetate and ethoxymethylene malononitrile were synthesized from the reaction of malononitrile or ethylcyanoacetate with triethyl orthoformate or orthoacetate in N, N-dimethylacetamide under microwave irradiation. In a similar manner, substituted pyrazoles were synthesized from the reaction of ethyl (ethoxymethylene)cyanoacetate and ethoxymethylene malononitrile with phenylhydrazine. These pyrazoles were converted to pyrazolo[3, 4-d]thiopyrimidines upon treatment with arylisothiocyanate and thiourea under microwave irradiation.