2-Chloroethyl methyl sulfide → 3-methyl-6-(2-methylsulfanylethyl)-5,6,7,8-tetrahydro-1H-pyrido[4,3-d]pyrimidine-2,4-dione

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Reaction Steps

36.3 g of 3-methyl-5,6,7,8-tetrahydro-1H-pyrido[4,3-d]-pyrimidine-2,4-dione, 23 g of 1-chloro-2-methylsulfanylethane (97% pure), 17.4 g of lithium bromide and 27 g of ethyldiisopropylamine in 700 ml of dimethylformamide were stirred for 14 h at 50° C. After the reaction mixture had been concentrated under reduced pressure, the residue was taken up with 400 ml of water and 400 ml, of dichloromethane, the pH was adjusted to 8 with sodium bicarbonate, with stirring, and the mixture was worked up by extraction with dichloromethane and water. 23 g of 3-methyl-6-(2-methylsulfanylethyl)-5,6,7,8-tetrahydro-1H-pyrido[4,3-d]pyrimidine-2,4-dione were obtained from the combined dichloromethane phases after drying, concentration and recrystallization of the residue from isopropanol.

Provenance & Evidence