tert-Butyl acetate → L-Glutamic acid di-tert-butyl ester

Participants

Reaction Steps

Acetic acid 1,1-dimethylethyl ester (1742 g; 2 L; 15 mol) (commercial product), 70% aq. perchloric acid (51 mL; 0.59 mol) and L-glutamic acid (78.8 g; 0.54 mol) (commercial product) were stirred at 25° C. over 5 days. After addition of a solution of K2CO3 (41.46 g, 0.3 mol) in H2O (140 mL) to the reaction mixture, the organic phase was separated, washed with water (2×500 mL), dried (NaSO4) and concentrated to dryness. The residue (27.2 g) was dissolved in Et2O (200 mL) and extracted with 1N HCl (2×70 mL), the combined aqueous phase was washed with Et2O (40 mL) and collected with the aqueous phases previously obtained from the first neutralization and successive washings. Addition of 10 N NaOH up to pH 8.8 led to an emulsion which was extracted with Et2O (2×600 mL). The combined organic phases were washed with H2O (250 mL), dried and evaporated to give the desired compound (57.7 g; 0.22 mol). Yield 41%.

Provenance & Evidence