Ethyl 7-bromo-1H-indole-2-carboxylate → (r)-7-Bromo-1-(2-tert-butoxycarbonylamino-1-methyl-ethyl)-1h-indole-2-carboxylic acid ethyl ester

Participants

Reaction Steps

A solution of 8.1 g (30.1 mmol) 7-bromo-1H-indole-2-carboxylic acid ethyl ester in 120 ml N,N-dimethylformamide was cooled to 0° C. and 3.55 g (31.6 mmol) potassium tert-butoxide was added. After 30 min., 7.86 g (33.1 mmol) (S)-5-methyl-2,2-dioxo-[1,2,3]oxathiazolidine-3-carboxylic acid tert-butyl ester were added and the cooling bath was removed. After 20 h the reaction mixture was poured on 10% aqueous citric acid solution and ethyl acetate. The organic layer was dried over magnesium sulfate, filtered and evaporated. The resulting yellow oil was chromatographed on silica gel (0.032-0.063 mm) with tert-butyl methyl ether: n-hexane (1:8) as eluant to give the desired compound as a yellow oil. ISP-MS: m/e=427.3 ([M+H+]).

Provenance & Evidence