Potassium Carbonate → HCID 19380167, compound

Temperature

0 °C

7.5 g. N-Amino-3-chloropyridinium mesitylene-sulphonate (see J. Chem. Soc. Perkin I, 2580/1973) 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.).

1. temperaturewith cooling
2. customThe precipitate obtained
3. filtrationis filtered off with suction
4. customthe filtrate is evaporated
5. customthe residue obtained
6. customis purified by chromatography on silica gel with methylene chloride/5-10% methanol
7. customThere are obtained 2.7 g
8. dissolutionof the N-acetoacetylated compound which is dissolved in 100 ml
9. stirringThe reaction mixture is stirred for 2 days at ambient temperature
10. customfinally evaporated
11. dissolutionThe residue is dissolved in 100 ml
12. temperaturedry dimethylformamide, the solution is cooled
13. additionmixed with 7 g
14. stirringThe reaction mixture is stirred for 1 hour at 0° C. and for 30 hours at ambient temperature
15. distillationThe dimethylformamide is distilled off
16. dissolutionthe residue is dissolved in water/ethyl acetate
17. customThe ethyl acetate phase is separated off
18. customdried
19. customevaporated
20. customThe product obtained
21. customis purified by column chromatography on silica gel with methylene chloride/ethyl acetate (20:1 v/v)
22. customThere is obtained 0.8 g

ORD record

ord-473936a8571b4885ad8bfab299d180c5

Source dataset

uspto-grants-1993_08

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US05234818