Triethylamine → Allyl-N-(tert-butoxycarbonyl)-O-[(4-nitrophenoxy)carbonyl]-L-tyrosinate

Participants

Reaction Steps

36.7 g (114.3 mmol) N-Boc-L-tyrosine allyl ester, 23.0 g (114.3 mmol) 4-nitrophenyl chloroformate, 17.5 ml (125.7 mmol) triethylamine and 1.40 g (11.4 mmol) 4-dimethylamino pyridine were combined in 1000 ml dichloromethane and stirred at room temperature for 2 h. The reaction mixture was extracted with approx. 500 ml water and with approx. 250 ml brine and dried over approx. 100 g sodium sulfate. The solvent was removed by rotary evaporation (approx. 40° C., approx. 200 mbar, approx. 30 min.) and the product was dissolved in warm diethyl ether and crystallized over night at 4° C. The crystals were filtered of, washed with cold diethyl ether and dried in high vacuum (approx. 0.1 mbar, 18 h). The yield was 29.86 g, (59.6 mmol, 52% of theory) of the desired product.

Provenance & Evidence