SYNTHESIS OF -2-PHENYLTHIENO(-FURO-)[2,3-D]PYRIMIDIN-4(3H)-ONES

The reactions of do-4,5-dihydro-3-thiophene(-3-furan-)carbonitriles 1a -c (and 11a-c) with acetic (or propionic) anhydride in the presence of tin(IV) chloride give the corresponding 2-phenylthieno(-furo-)-[2,3-d ]pyrimidin-4(3H)-ones 2a-c (and 12a-c) or propionylthieno(-furo-)[2,3- d]pyrimidin-4(3H)-ones 3a-c (and 13a-c). Hydrolysis of compounds 2a-c (and 12a-c) or 3a-c (and 13a-c) lads to the corresponding yl-2-benzami do-4,5-dihydro-3-thiophene-(-3-furan-) carboxamides 5a-c (and 15a-c). The reaction of compounds 4a,b (or 14a, b) with acid anhydrides in the presence of potassium carbonate or triethylamine gives the correspond ing 3-acyl-2-benzamido-4,5-dihydrothiophenes (or furans) 9, 10, 16 and 17.