Ammonium Chloride → HCID 178509251, compound

Participants

Reaction Steps

To a solution of tert-butyl [(5-chloro-2-fluoro-4-{2-[3-nitro-1-(tetrahydro-2H-pyran-2-yl)-1H-pyrazol-4-yl]-4-(trifluoromethyl)phenoxy}phenyl)sulfonyl]1,3-thiazol-4-ylcarbamate (Preparation 872, 55 g, 74 mmol) in ethanol (800 mL) was added saturated aqueous ammonium chloride solution (200 mL, 3000 mmol) and iron (65 g, 1200 mmol). The reaction solution was heated at 80° C. for two hours at which point iron (10 g, 185 mmol) was added and the mixture heated for an additional hour. The solution was cooled, filtered and adjusted to pH=9 with saturated aqueous sodium bicarbonate solution. The mixture was filtered and then concentrated to remove most of the ethanol. The resulting slurry was extracted with dichloromethane (4×). The organic extracts were combined, dried over anhydrous magnesium sulfate, filtered, and concentrated to provide the free amine as an orange oil. Purification by manual flash column chromatography using 40% then 75% ethyl acetate/hexanes and a 5×31 cm column provided a mix of Boc protected sulphonamide and non-Boc protected sulphonamide free amine as an orange oil. To this mixture was added an HCl (g) saturated methanol solution (400 mL) and the mixture heated at 60° C. for 7 hours. The reaction solution was cooled and concentrated to give a white solid. The solid was redissolved in methanol, heated to reflux and ethyl acetate added until just before a precipitate formed. It was then cooled, washed with ethyl acetate and dichloromethane to provide the title compound as a white solid. This was repeated until no more clean product was obtained. The impure filtrate was purified by prep HPLC, the product fractions concentrated and the TFA salt exchanged for an HCl salt. All product was combined, dissolved in methanol, filtered, concentrated and isolated as a white solid with 1.5 eq of HCl present (30.3 g, 70%) via trituration with dichloromethane.

Provenance & Evidence