3- Acetoxy-2-methyl-4//-pyrido

A combined silylation-animation procedure340 affords a 74% yield of 6-(hydroxymethyl)-pyrido[2,3-flT)pyrimidine-2,4-diamine (14) in one synthetic step directly from 6-(acetoxy-methyl)pyrido[2,3-<7]pyrimidine-2,4(l//,3//)-dione (13).314... 

Pyrido 3,2-d pyrimidin 6-(Acetoxy-methyl)-2,4-dihydroxy- E9c, 178 (5-Oxid-Red. C-H C-OAc)... 

Only resinous products and methyl 6-acetamidopyridine-3-carboxylate were obtained when methyl 6-aminopyridine-3-carboxylate was reacted with ethyl 2-acetoxyacetoacetate by heating in phosphorus pentoxide, methanesulfonic acid, or polyphosphoric acid in the absence or presence of a solvent such as toluene, xylene, or methylene chloride. However the desired methyl 3-acetoxy-2-methyl-4-oxo-4//-pyrido[ 1,2-a]pyrimidine-7-carboxylate 93 was obtained when the above components were reacted in N, A-dimethylacetamide in the presence of polyphosphoric acid at 100°C for 48 hours (84FES837). 

Treating 3-acetoxy-2-methyl-4/f-pyrido[l,2-sodium hydrogen carbonate in methanol at 60°C for 4 hours, then at ambient temperature for 16 hours, gave 3-hydroxypyridopyrimidine-7-carboxylate 416 (84FES837). The free hydroxyl group of compound 416 was alkylated with an alkyl iodide in dimethylformamide in the presence of potassium carbonate at room temperature or with 2-methoxyethoxymethyl chloride in dichloromethane in the presence of diisopropylethylamine at ambient temperature for 3 hours to give 3-alkoxy derivatives 417. 

Bis-(4-acetoxyphenyl)methyl]pyridine N-oxide and ethyldiisopropylamine hydrobromide as weak proton acid in acetic anhydride refluxed vigorously for 1 hr. -> 3-acetoxy-10-(4-acetoxyphenyl)-pyrido[l,2-a]indole. Y 81%. - Instead of acetic anhydride, 1,1,2,2-tetrachlorethane may be used as medium. J. Sdinekenburger, Ardi. Pharm. 306, 360 (1973). 

Satyanarayana et al. (2013) synthesized 3-substituted-2H-pyrido[l,2-a]pyrimi-din-2-ones via microwave induced cyclocondensation of methyl 2-(acetoxy(phenyl) methyl)acrylate with 2-aminopyridines under solvent-free conditions in the presence of a catalyst and with good yields and high selectivity. 

---