Diisopropylethylamine → 2-[(4-Hydroxy-benzo[b]thiophene-5-carbonyl)-amino]-2-methyl-propionic acid tert-butyl ester

Participants

Reaction Steps

To a solution of 300 mg 4-Hydroxy-benzo[b]thiophene-5-carboxylic acid in 5 ml N,N-dimethylformamide were added 42 mg 1-hydroxy-benzotriaziole and 285 mg 2-amino-2-methyl-propionic acid tert-butyl ester hydrochloride. At 0° C. 0.77 ml (600 mg) ethyl-diisopropyl-amine and 444 mg (3-dimethylamino-propyl)-ethyl-carbodiimide hydrochloride were added. After 16 h at room temperature 0.51 ml (400 mg) ethyl-diisopropyl-amine and 444 mg (3-dimethylamino-propyl)-ethyl-carbodiimide hydrochloride were added, and after additional 16 h the reaction was diluted with ethyl acetate and washed with brine. The organic layer was dried over magnesium sulphate and concentrated. The resulting residue was purified by flash chromatography (silica, heptane/ethyl acetate) to afford 315 mg 2-[(4-hydroxy-benzo[b]thiophene-5-carbonyl)-amino]-2-methyl-propionic acid tert-butyl ester.

Provenance & Evidence