3-Acetyl-4-methylthio-27/-pyrido

Acetyl-4-phenylamino-2if-pyrido[l, 2-a]pyrimidin-2-one (285) was obtained when A-(2-pyridyl)acetoacetamide 332 (R = H) was first treated with PhNCS in the presence of K2CO3 and BnEtsNCl, then with Mel and NEt3, and then the reaction mixture was heated rapidly to 80 °C (95MI2). Reaction of A-(2-pyridyl)acetoacetamides 332 with CS2 in the presence of K2CO3 and a catalytic amount of BnEt3NCl, then with 1 or 2 equiv of Mel afforded 3-acetyl-2-hydroxy-4Ef-pyrido[l,2-<2]pyrimidine-4-thiones 333 and 3-acetyl-4-methylthio-2i/-pyrido[l,2-a]pyrimidin-2-one (334), respectively (96MI22). 

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