Thirty nine new 3, 4-di (substituted) oxy-N2, N5-bis (substituted) thiophene-2, 5- dicarbohydrazides were synthesized starting from ethyl thiodiglycolate through multi-step reactions. In the synthetic sequence, 3, 4-dihydroxythiophene-2, 5-diester (1) was obtained by condensing the ethyl thiodiglycolate with diethyl oxalate. It was derivatized using different alkyl halides to give disubstituted thiophene esters (2–5), which were then converted to ...