2-Methylthieno pyrimidines, reaction

A direct approach to 3-aryl-2-chloro-4-iminothieno[2,3-d]pyrimidines 65a from A-aryl isocyanide dichlorides and o-aminocarbonitriles 48 was devised by Shishoo and Jain (92JHC883). 3-Aryl-4-imino-2-methylthieno [2,3-rf]pyrimidines 65b were obtained by heating a mixture of 2-acetyl-aminothiophene-3-carbonitriles 64a, phosphorus pentoxide, a primary ary-lamine hydrochloride, and /V,7V-dimethylcyclohexylamine hydrochloride in a molar ratio 1 6 4 4, at 160°C (88CS195 91EUP452002). Following similar reaction conditions but adding 8 parts of water to this reaction mixture... 

Dechlorination of 4-chloro-6-methylthieno[2,3-d]pyrimidine 164 with zinc in ethanol and acetic acid at 80°C gave compound 165. The latter was subjected to the Reissert reaction using two equivalents each of tributyltin cyanide and acyl chloride in dichloromethane at room temperature. With benzoyl chloride the mono-Reissert adduct 166 was obtained, whereas with acetyl chloride the di-Reissert product 167 (86JHC545). 

A multistep preparation of a thieno[3,2-e]-l,4-diazepin-2(3//)-one (285) has been accomplished, starting from the thienooxazinone 284 obtained from methyl 3-acetylaminothiophene-3-carboxylate (283) and phosphorus pentachloride.154 Similarly, 3-methylthieno[2,3-d]pyrimidin-4-(3//)-ones (288) were obtained in an exothermic reaction by heating methyl 2-acylamino-3-thiophenecarboxylates (286) with N,AT-dimethylphosphordiamidate (287) up to 250°C155 (Scheme 78). Ethyl 2-acylamino-3-pyridinecarboxylate (289) gave, on heating with excess amine hydrochloride and phosphorus pentoxide/iV,AP-dimethylcyclohexylamine, a series of pyrido[2,3-d]pyrim-idine-4(3if)-ones (290).156... 

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