L-Valine → (2S)-2-((methoxycarbonyl)amino)-3-methylbutanoic acid

Participants

Reaction Steps

Methylchloroformate (14.5 mL, 0.188 mol) was added over 15 min to a cooled (0-6° C.) mixture of (S)-2-amino-3-methyl-butyric acid (20.0 g, 0.171 mol), NaOH (6.80 g, 0.171 mol) and sodium carbonate (18.1 g, 0.171 mol) in water (200 mL). The cooling bath was removed and the mixture was stirred at ambient temperature overnight. Conc. aqueous HCl (30 mL) was added to the reaction mixture to adjust pH to ˜1. A solid formed and the mixture was stirred for 90 min. The mixture was filtered and the solid was dried overnight under reduced pressure at 40° C. to provide the title intermediate (27.8 g, 93% yield). 1H NMR (CD3OD, 400 MHz) δ (ppm) 4.87 (br. s, 4H), 4.05 (d, J=5.49, 1 H), 3.65 (s, 3H), 2.25-2.05 (m, 1H), 0.98 (d, J=6.87, 3H), 0.94 (d, J=6.87, 3H).

Provenance & Evidence