3- Cyano-2-methylthio-477-pyrido

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). 

Reaction of 1,3-propanediamine and 3-cyano-4-methyl-6-methylthio-l-phenyl-2-0X0-],2-dihydropyridine-5-carboxylate 385 yielded 7-cyano-8-methyl-6-oxo-],2,3,4-tetrahydro-6/7-pyrido[],2-a]pyrimidine-9-carboxylate (386) (94JHC393). 

Reaction of 3-amino-2-cyano-4-[(phenylamino)(methylthio)methylene]-2-pentenedioate (408) with a large excess of 1,3-propanediamine afforded ethyl 6-imino-l, 2,3,4-tetrahydro-6//-pyrido[l, 2-n]pyrimidine-9-carboxylate (409) as depicted in Scheme 16 (95JHC477). 

The 4-imino group of 3-cyano-4-imino-2-methylthio-4//-pyrido[ 1,2-a]-pyrimidine was transformed to the 4,4-diamino group with amines and to the 4-methylimino group with methyl iodide in dimethylformamide in the presence of potassium carbonate.268 On the action of dimethyl acetylenedi-carboxylate in dimethylformamide at 150°C, the 1,4-diazacycl [3,3,3] azine (234 R = CH3S) was formed.314... 

Cyano-4-imino-2-methylthio-4//-pyrido[l, 2-c]pyridine (72), obtained from 2-pyridylacetonitrile, and dimethyl cyanamidedithiocar-... 

Treatment of l-imino-4-cyano-3-methylthio-l/7-pyrido[l,2-c]pyrimidine (105) with morpholine afforded the 1-amino-l-morpholine derivative (106). Reaction of the 1-imino derivative (105) with dimethyl acetylenedicarboxy-late gave the diaza[3,3,3]azine derivative (107) (75YZ13). Treatment of 105 with concentrated H2SO4 or with acetic acid yielded 4-aminocarbonyl-3-methylthio- l//-pyrido[l, 2-c]pyrimidin-l-one and 4-cyano-3-methylthio-l//-pyrido[l,2-c]pyrimidin-l-one, respectively. Reaction of the latter derivative with morpholine afforded the 3-morpholino derivative (75YZ13). Hydrolysis of 4-cyano-3-imino-2,3,5,6,7,8-hexahydro-l//-pyrido[l,2-c] pyrimidine-l-(thi)ones or their 3-(aminocarbonyl)imino derivatives in boiling 70% HCl gave 3-oxo derivatives (78MI1). 

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