Fused thiazole from 2-(4-phenyl-3(h)-thiazol-2-ylidene) malononitrile: A novel synthesis of thiazolo[3,2- c ]pyrimidine, thiazolo[3,2- a ]pyridine, pyrazolo[3,4- d ]-1,3-thiazolino[2,3- f ]pyrimidine and arylazo thiazolylidene derivatives

2-(4-Phenyl-3(H)-thiazol-2-ylidene) malononitrile was obtained from cyclo-condensation of cyanatoacetophenone with malononitrile and not via the Knoevenagel condensation, depending on the reaction conditions. The synthesis of thiazolo[3,2- a ]pyridine, thiazolo[3,2- c ]pyrimidine, pyrazolo[3,4- d ]-1,3-thiazolino[2,3- f ]pyrimidine and some azo derivatives of thiazolidene are described.