R = Me, Et, i-Pr, Ph
| Triazolidine-3-thiones (3) with an ethoxycarbonyl substituent in position 5 are accessible from phenylhydrazones of a-oxo esters (2). The reaction in these cases demands both elevated reaction temperatures and prolonged reaction times. | If R in (2) is a second carboxylix acid derivative (ester or amide) no reaction occurs at all. No reaction was observed with potassium cyanate, and only triazolidine-3-thiones (3) of this type are accessible so far. |