Dimethyl oxalate → HCID 22315365, compound

Participants

Reaction Steps

To a stirred solution of 3,5-difluoro-4-methoxyacetophenone from Step 1 (6.46 g, 34.70 mmol) and dimethyl oxalate (6.15 g, 52.05 mmol) in methanol (80 mL), was added sodium methoxide solution (13.4 mL of 25% solution, 58.99 mmol) in one portion and the reaction stirred overnight. The crude reaction was diluted with methylene chloride, washed with potassium bisulfate (0.1N solution, brine, dried over MgSO4, filtered, and concentrated in vacuo yielding methyl 4-(3,5-difluoro-4-methoxyphenyl)-2,4-dioxo-butanoate as an off white crystalline solid which was used as is. A mixture of 4-(3,5-difluoro-4-methoxyphenyl)-2,4-dioxo-butanoate and 4-sulfonamidophenylhydrazine hydrochloride salt (7.76 g, 34.70 mmol) dissolved in methanol was warmed to reflux for 9 hours. Upon allowing the clear reaction to cool to room temperature, a crystalline precipitate formed which was collected by vacuum filtration yielding 5.45 g, (37% based upon the 3,5-difluoro-4-methoxyacetophenone) of methyl 1-(4-aminosulfonylphenyl)-5-(3,5-difluoro-4-methoxyphenyl)-1-H-pyrazole-3-carboxylate as an off-white solid: mp 185-190° C.; 1H NMR (CDCl3/300 mHz) 7.95 (d, J=8.86, 2H), 7.49 (d, J=8.86, 2H), 7.02 (s, 1H), 6.77 (m, 2H), 4.99 (s, 2H), 4.04 (s, 3H), 3.98 (s, 3H); 19F NMR (CDCl3/300 mHz) −126.66. Anal. calc'd or C17H13F2N3O3S: C, 51.06; H, 3.57; N, 9.92. Found: C, 51.06; H, 3.54; N, 9.99.

Provenance & Evidence