Diisopropylethylamine → (S)-2-[(S)-3-(4-But-3-enyloxy-phenyl)-2-tert-butoxycarbonylamino-propionylamino]-4-ethyl-pentanoic acid methyl ester

Participants

Reaction Steps

Carboxylic acid 19 (2.60 g, 7.75 mmol), HATU (3.24 g, 8.53 mmol) and leucine methyl ester hydrochloride (2.82 g, 15.5 mmol) were dissolved in DMF (40 mL). DIPEA was added (5.40 mL, 31.0 mmol) and the reaction mixture was stirred at rt for 18 h. before being partitioned between EtOAc and 1M hydrochloric acid. The organic phase was washed sequentially with 1M hydrochloric acid and brine before being dried (MgSO4), filtered and concentrated in vacuo. The crude material was purified by flash chromatography on silica using a gradient of EtOAc and (50/70) petroleum ether to yield a white solid, 2.30 g, 64%. Rf=0.34 (1/2 EtOAc/(50/70) petroleum ether).

Provenance & Evidence