Diisopropylethylamine → (S)-1-{(S)-2-[(S)-2-(tert-butoxycarbonyl-methyl-amino)-propionylamino]-2-phenyl-acetyl}-2,3-dihydro-1H-indole-2-carboxylic acid ethyl ester

Participants

Reaction Steps

In a 50 mL round-bottomed flask, (S)-2-(tert-butoxycarbonyl(methyl)amino)propanoic acid (1.52 g, 7.48 mmol, Eq: 1.5) and HATU (1.9 g, 5 mmol, Eq: 1) were combined with DCM (20 mL) to give a light yellow suspension. (S)-1-((S)-2-amino-2-phenyl-acetyl)-2,3-dihydro-1H-indole-2-carboxylic acid ethyl ester hydrochloride (1.8 g, 5 mmol, Eq: 1) was added and followed by diisopropylethylamine (7 mL, 40 mmol, Eq: 8). The reaction was stirred at rt overnight. The crude reaction mixture was concentrated in vacuo, and then dissolved in EtOAc (75 mL). The solution was washed with water and brine, dried and concentrated in vacuo. The crude material was purified by flash chromatography (10% to 30% EtOAc in hexanes) to afford (S)-1-{(S)-2-[(S)-2-(tert-butoxycarbonyl-methyl-amino)-propionylamino]-2-phenyl-acetyl}-2,3-dihydro-1H-indole-2-carboxylic acid ethyl ester (2.3 g) as a white foam, m/z=510 (M+H).

Provenance & Evidence