Abstract 2-Mercapto-thieno [2.3-d] pyrimidine-4 (3 H)-one, 2-mercapto-5.6. 7.8-tetrahydro-[1] benzothieno [2.3-d] pyrimidin-4 (3 H)-one and derivatives thereof were synthesized by cyclisation of esters or amides of the corresponding 2-amino-thiophene-3-carboxylic acids: either by direct reaction with thiourea or by reaction with methyl-or allyl-isothiocyanate via the corresponding N, N′-disubstituted thioureas as intermediates.
![3-ALLYL-2-MERCAPTOTHIENO[2,3-D]PYRIMIDIN-4(3H)-ONE Structure](https://image.chemsrc.com/caspic/012/51550-04-0.png)
![3-ALLYL-5,6-DIMETHYL-2-THIOXO-2,3-DIHYDROTHIENO[2,3-D]PYRIMIDIN-4(1H)-ONE Structure](https://image.chemsrc.com/caspic/348/51486-16-9.png)
![2-mercapto-3,5-dimethylthieno[2,3-d]pyrimidin-4(3H)-one Structure](https://image.chemsrc.com/caspic/424/51486-14-7.png)