Dimethyl Sulfoxide → (2S,3S)-2-(tert-butoxycarbonylamino)-3-(5-cyano-2-nitrophenylamino)butanoic acid

Participants

Reaction Conditions

Reaction Steps

A mixture of (2S,3S)-3-amino-2-(tert-butoxycarbonylamino)butanoic acid (3.14 g, 14.4 mmol), dimethylsulfoxide (40 ml), 3-fluoro-4-nitrobenzonitrile (2.63 g, 15.8 mmol), and sodium bicarbonate (4.83 g, 57.5 mmol) was stirred at 55° C. for 3 h. Additional NaHCO3 (0.9 g) was added and the mixture was stirred at 60° C. for 1 hour, then cooled to RT, diluted with cold sat. Na2CO3, and washed with MTBE. The aqueous phase was carefully acidified to pH ˜4 with solid citric acid and extracted with EtOAc (three times). The combined organic layers were washed with H2O twice and brine, dried over Na2SO4, filtered, and concentrated to provide (2S,3S)-2-(tert-butoxycarbonylamino)-3-(5-cyano-2-nitrophenylamino)butanoic acid (5.7 g, quant.).

Provenance & Evidence