Ethyl thieno pyrimidine-6-carboxylate

Cyclocondensation of 3-cyano-2-methylthio-4//-pyrido[l, 2-u]pyrimidin-4-ones and ethyl mercaptoacetate in boiling EtOH in the presence of NaOEt afforded 4//-pyrido[l,2-u]thieno[2,3-r/ pyrimidin-4-ones 210 (00HC571). 2-Methylthio-4-oxo-4//-pyrido[l,2-u]pyrimidine-3-carboxylates 211 and mercaptoacetates afforded tricyclic derivatives 212 (93MIP1). Cyclocondensation of 2-methylthio-4-oxo-4//-pyrido[l, 2-u]pyrimidin-3-car-bonitriles 213 with H2NNH2 H2O and with guanidine HCl afforded tricyclic derivatives 214 and 215, respectively (96FES781). 

Cyclocondensation of ethyl 2-methylthio-4-oxo-4/f-pyrido[l,2-a]py-rimidine-3-carboxylate 459 and ethyl mercaptoacetate in acetonitrile in the presence of potassium carbonate at 60°C for 2 hours, then at room temperature for 16 hours gave pyrido[l,2-a]thieno[2,3-t/]pyrimidine-2-carboxylate 460 (88CP1232904). 

NaOEt afforded ethyl 4-oxo-2-thioxo-l,2,3,4,5,6,7,8-octahydropyrido[4,3 4,5] thieno[2,3-c/]pyrimidine-7-carboxylate (16) (1999JHC1119). 

Ethyl 4,5-diamino-2-(dimethylamino)thieno[2,3-z/]pyrimidine-6-carboxylate (142) was prepared in 93% yield from 4-amino-6-chloro-2-(di-methylamino)pyrimidine-5-carbonitrile (143) with ethyl 2-mercaptoacetate in refluxing EtOH-THF (5 1) (2000S255). 

Formamide is a powerful C-N-heterocyclization reagent. 2-Formamidino derivatives are intermediates. Robins transformed 3-aminopyrazole-4-carboxamide to a 4-oxopyrazolo[3,4-d]pyrimidine (155)95 by heating in formamide. In boiling formamide, 155 was obtained from ethyl 3-aminopyrazole 4-carboxylate (38)31 (Scheme 35). From the enamino ester 59 and formamide a 5,6,7,8-tetrahydrobenzo [b] thieno [2,3-d ] pyrimidin-4-one (156) was obtained,96 as well as the aromatic thionaphtheno[2,3-d]-pyrimidine (157).97 This heterocyclization method shows broad applicability... 

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... 

Ethoxalyl chloride (Et02C—COC1) in pyridine converted 2-amino-4,5,6,7-tetrahydrobenzo[b]thiophene-3-carboxamide to the 2-ethoxalylamino analog, which was heated at 260°C to give ethyl 5,6,7,8-tetrahydro-4-oxobenzo-thieno[2,3-d]pyrimidine-2-carboxylate (142) (moderate yield).215... 

Thieno[2,3- /]pyrimidines have been synthesized from 5-acylamino-2,3-dialkylthiophen-4-aldehydes. 2-Amino-3-cyano-thiophens have been transformed into the 2-cyanamino-3-cyano-thiophens and ring-closed to 4-aminothieno[2,3-Raney nickel to the 4-oxo-pyrimidine (263). ... 

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