Bromine → 3-Methyl-2-(3-oxobenzo[d]isothiazol-2(3H)-yl)pentanoic acid

Participants

Reaction Steps

A stirred, room temperature suspension of 5.3 g (10.0 mmol) of [S-(R*,R*)]-2-[2-[2-(1-carboxy-2-methylbutylcarbamoyl)phenyldisulfanyl benzoylamino]-3-methylpentanoic acid (prepared by the general method of Example 5) in 200 mL of dichloromethane was treated dropwise with 2.4 g (15.0 mmol) of liquid bromine. The reaction mixture was stirred at room temperature for 2 hours, and the solvent was evaporated in vacuo. The residue was triturated with dichloromethane, which was also evaporated in vacuo to remove excess bromine. The residue was partitioned between dichloromethane/5% sodium bicarbonate (200 mL each). The aqueous layer was separated, washed with dichloromethane, and acidified to pH 1.5 with 6.0M hydrochloric acid. After extracting with dichloromethane (2×75 mL), the combined organic layers were washed with water, dried (MgSO4), filtered and evaporated in vacuo to give 4.8 g of the title compound, mp 50°-52° C.

Provenance & Evidence