hydroxylamine-O-sulfonic acid → HCID 178498984, compound

Participants

Reaction Conditions

Reaction Steps

A separate reaction vessel was charged with water (280 mL, 7 volumes) and sodium hydrogencarbonate (1.5 equiv, 38.2 g). The water/sodium hydrogencarbonate mixture was cooled to 5° C. under nitrogen atmosphere. Hydroxylamine-O-sulfonic acid (1.2 equiv, 41.1 g) was added over 5 minutes, and the mixture was stirred 15-30 minutes. The 2,2-Bis-methoxycarbonyl-1-methylsulfanyl-ethenethiol anion/acetonitrile solution from Example 1 was added over 60-70 minutes. The mixture was warmed to 25° C. over 1 hour, then held for 16 hours at 25° C. Most of the acetonitrile was removed by vacuum distillation (130 Torr, 50° C.). The residue was cooled to room temperature, acidified to pH ˜1 by addition of 37% hydrochloric acid (32 mL). The solids were granulated for 16 hours at 25° C. The slurry was filtered, and the filter cake was washed 3×100 mL with water, once with 200 mL 1:3 ethyl acetate:hexanes (v/v), and once with 100 mL 1:3 ethyl acetate:hexanes (v/v). The wet cake (50.5 g) was dried in a vacuum oven for 16 hours to give 3-Hydroxy-5-methylsulfanyl-isothiazole-4-carboxylic acid methyl ester, providing 45.4 grams (73% yield). 1H NMR: (DMSO-d6) δ 11.92 (s, 1H); 3.74 (s, 3H); 2.53 (s, 3H). MS: (API-ES pos) 206 (M+H)+, base.

Provenance & Evidence