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Part-IISynthesis of PyrimidinesOOR 2R 1S9bOC 2 H 5NH 2CNCOOR 3dryHCl/AcOHR 1NHCOOR 3R 2N STiprinast, R 1 = CH 3 , R 2 = (CH 3 ) 2 CHCH - 2 , R 3 = H.Some European workers 53 have synthesized a series of 3-phenylthieno[2,3-d]pyrimidin-4(3H)-ones by the cyclization of 2-amino-3-carbethoxythiophenes with benzonitrile inthe presence of dry HCl gas. These compounds have exhibited potent analgesic and antiinflammatoryactivities.OCO 2 C 2 H 5R 1R 2 SNH 29bC 6 H 5 CNdry HClR 2R 1SN NHC 6 H 5R 1 , R 2 = -(-CH 2 -) 3 -; -(-CH 2 -) 4 -, -(-CH 2 -) 5 -; -CH(CH 3 )-(-CH 2 -) 3 -; -(-CH 2 -) 2 -CH(CH 3 )-CH 2 --CH 2 -CH(CH 3 )-(-CH 2 -) 2 -; R 1 = C 6 H 5 , R 2 = H.The dry HCl gas catalyzed reaction of 2-aminothiophene-3-carboxamide 10a withacetonitrile and benzonitrile has yielded the corresponding 2-substituted-4-oxothienopyrimidines. Similar reaction of 2-amino-N-substituted thiophene-3-caboxamide 10b with acetonitrile could be expected to yield the 3-N-substituted 2-substitutedthienopyrimidin-4-one. However, the reaction when actually conducted led tothe formation of the 3-unsubstituted thienopyrimidin-4-one (R = CH 3 ), as the onlyproduct. 23,31,54OONH 2RCNNHS10adry HClNH 2CH 3 CNSR=CH 3 , C 6 H 5NROdry HClOCH 3S10bNHCH 3CH 3 CNXdry HClNH 2SNNCH 3241