Abstract
The review summarizes the synthesis of different thiophene, pyrazole, and thiazole derivatives by refluxing 9a in ethanol with a catalytic amount of TEA or leaving it in DMF containing potassium carbonate at room temperature overnight to afford the corresponding thiophene derivative 10a. In addition, cyclization of Schiff bases with thioglycollic acid in the presence of a catalytic amount of ZnCl2 yielded novel thiophene derivatives. Condensation of 2-substituted-4-methylythio semi-carbazides 92 with carbonyl compounds under strong acidic conditions afforded 2-thiazolines. Also, carboxylic acid reacted with 2-thioethylamine in the presence of triphenylphosphine and triethylamine to afford 2-thiazolines 98.