Acetone → 2-(3-Bromophenyl)-3-hydroxy-3-methylbutane-2-sulfonamide

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Reaction Steps

Under inert gas, 2.82 g of N-(2,4-dimethoxybenzyl)-1-(3-bromophenyl)ethanesulfonamide was initially charged in 40 ml of THF, and then, at a temperature of −76° C., 10.00 ml of a 1.6 N methyllithium solution in diethyl ether were added dropwise and the mixture was stirred at constant temperature for 5 minutes. Subsequently, 1.50 ml of acetone were added. After stirring for 5 minutes, the reaction solution was allowed to warm up to room temperature, and the solvent was removed under reduced pressure. The residue was dissolved in 30 ml of dichloromethane, 2 ml of trifluoroacetic acid were added and the mixture was stirred at room temperature for 90 minutes. The conversion was checked by LCMS, a further 2 ml of trifluoroacetic acid were added and the mixture was stirred for 75 minutes. Then, 40 ml of water were added while stirring vigorously, the phases were separated and the aqueous phase was washed again with 2×30 ml of dichloromethane. The combined organic phases were concentrated by rotary evaporation and coevaporated twice with toluene. The crude product was purified by means of normal phase chromatography using a Flashmaster with a dichloromethane/methanol gradient. The product-containing fractions were combined and concentrated by rotary evaporation. This gave the product (1.10 g) with a molecular weight of 322.2 g/mol (C11H16BrNO3S); MS (ESI): m/e=341 (M+H2O+H+).

Provenance & Evidence