1-Hydroxybenzotriazole → (2R)-1-[3-methoxy-5-(trifluoromethyl)-benzoyl]-2-[4-chloro-3-(tert-butyldimethylsilyloxy)benzyl]-4-benzylpiperazine

Participants

Reaction Steps

1-[3-(Dimethylamino)propyl]-3-ethylcarbodiimide hydrochloride (1.93 g) was added to a mixture of (2R)-4-benzyl-2-[4-chloro-3-(tert-butyldimethylsilyloxy)benzyl]-piperazine (2.90 g) and 3-methoxy-5-(trifluoromethyl)benzoic acid (1.48 g), 1-hydroxybenzotriazole (1.14 g) in dichloromethane (18 ml) at room temperature. After being stirred for 6 hours at the same temperature, the reaction mixture was poured into a mixed solvent of water (25 ml) and dichloromethane (15 ml). The aqueous layer was adjusted to pH 9 with aqueous sodium hydrogen carbonate solution. The organic layer was separated, washed with brine, dried over sodium sulfate, and concentrated under reduced pressure. The resulting residue was purified by column chromatography on silica gel (52 g) using a mixed solvent of hexane and ethyl acetate (2:1). The fractions containing the objective compound was collected and evaporated under reduced pressure to give a syrup of (2R)-1-[3-methoxy-5-(trifluoromethyl)-benzoyl]-2-[4-chloro-3-(tert-butyldimethylsilyloxy)benzyl]-4-benzylpiperazine (3.3 g).

Provenance & Evidence