Cyanoacetic acid hydrazide: An efficient access for the synthesis of multi‐functional azine and azole derivatives

Abstract

AbstractHerein, the synthesis of nitrogen‐containing heterocyclic scaffolds from heterocyclization of cyanoacetic acid hydrazide derivatives is described. Thiosemicarbazide derivative1aundergoes base‐mediated cyclization producing pyrazole derivative of type2. The triazolopyridine5was obtained by double cyclization of1aand benzylidene malononitrile. Compound1bcondensed with ethyl chloroformate to furnish pyrazolooxazine8. Compound1bwas added to benzoyl isothiocyanate under thermal condition to form oxadiazine derivative10while, keeping the above reactant under room temperature to form acyclic derivative11. Using CS2as a cyclizing agent for compound1byielded pyrazole derivative13. Treatment of1bwith I2resulted in oxidative cyclization producing pyridazine derivative14. Compound1ccyclized with benzoyl isothiocyanate forming triazolothiazine derivative18. While using cinnamoyl isothiocyanate, the acyclic product22was obtained. Compound1cwas condensed with formaldehyde leading to oxadiazole derivative25.