Potassium Carbonate → HCID 19380167, compound

Participants

Reaction Conditions

Reaction Steps

7.5 g. N-Amino-3-chloropyridinium mesitylene-sulphonate (see J. Chem. Soc. Perkin I, 258C/1973) are dissolved in 50 ml. dry dimethylformamide and mixed with 3.5 g. finely powdered potassium carbonate. 28 ml. of a 5M diketene solution in methylene chloride are added thereto with cooling. The reaction mixture is stirred for 30 minutes at 0° C. and for 2 hours at ambient temperature. The precipitate obtained is filtered off with suction, the filtrate is evaporated and the residue obtained is purified by chromatography on silica gel with methylene chloride/5-10% methanol. There are obtained 2.7 g. of the N-acetoacetylated compound which is dissolved in 100 ml. ethanol and mixed with 2.6 g. of finely powdered potassium carbonate. The reaction mixture is stirred for 2 days at ambient temperature and finally evaporated. The residue is dissolved in 100 ml. dry dimethylformamide, the solution is cooled and mixed with 7 g. methyl iodide. The reaction mixture is stirred for 1 hour at 0° C. and for 30 hours at ambient temperature. The dimethylformamide is distilled off and the residue is dissolved in water/ethyl acetate. The ethyl acetate phase is separated off, dried and evaporated. The product obtained is purified by column chromatography on silica gel with methylene chloride/ethyl acetate (20:1 v/v). There is obtained 0.8 g. 3-acetyl-4-chloro-2-methoxypyrazolo[1,5-a]-pyridine which is nitrosated and reduced analogously to Example 3. Yield: 0.3 g. of the title compound; m.p. 200°-230° C. (decomp.).

Provenance & Evidence