Hydrogen Bromide → N-((S)-3-bromo-2-hydroxypropyl)-5-chlorothiophene-2-carboxamide

Participants

Reaction Conditions

Reaction Steps

301.7 ml of a 33% solution of hydrobromic acid in acetic acid are added to a suspension of 100 g of N-((S)-2,3-dihydroxypropyl)-5-chlorothiophene-2-carboxamide (VIII) in 250 ml of glacial acetic acid at from 21 to 26° C. over a period of 30 minutes. Subsequently, 40 ml of acetic anhydride are added and the reaction mixture is stirred at from 60 to 65° C. for three hours. At 20 to 25° C., 960 ml of methanol are then added over a period of 30 minutes. The reaction mixture is stirred under reflux for 2.5 hours and then overnight at from 20 to 25° C. For workup, the solvents are distilled off under reduced pressure at approx. 95 mbar. The remaining suspension is admixed with 50 ml of 1-butanol and 350 ml of water. The precipitated product is filtered off with suction, washed with water and dried.

Provenance & Evidence