Triethylamine → 1-[4-(2,2,2-trifluoro-ethanesulfonylamino)-benzyl]-5-(2-methyl-[1,3]dioxolan-2-ylmethyl)-1H-indole-2-carboxylic acid ethyl ester

Participants

Reaction Steps

To a solution of crude 1-(4-amino-benzyl)-5-(2-methyl-[1,3]dioxolan-2-ylmethyl)-1H-indole-2-carboxylic acid ethyl ester (2 g, ≈5 mmol) in methylene chloride (25 ml) stirring at about -78° C. under nitrogen was added triethylamine (1.28 g, 1.76 ml, 12.7 mmol). The mixture was stirred for about two minutes, and 2,2,2-trifluoroethanesulfonyl chloride (2.03 g, 1.23 ml, 12.7 mmol) was added dropwise via syringe over about five minutes. The mixture was stirred at about -78° C. for about 45 minutes, then diluted with methylene chloride and water and warmed to room temperature. The organic layer was washed with brine, dried over sodium sulfate, and concentrated in vacuo to an oil. The oil was taken up in methanol (30 ml) and triethylamine (1 ml) and stirred for about two hours at room temperature. The mixture was poured into half-saturated ammonium chloride and extracted into ethyl acetate. The ethyl acetate was washed with brine, dried over sodium sulfate, filtered, and evaporated to give the title compound (2.85 g) as a foam containing some impurities, which was reacted without further purification.

Provenance & Evidence