Diazomethane → HCID 86585257, compound

Participants

Reaction Steps

N,O-Bis-Boc-(S)-tyrosine (6.00 g, 15.73 mmol) was dissolved in THF (40 mL), the solution stirred under an argon atmosphere and cooled in an ice bath. Isobutyl chloroformate (3.0 6mL, 23.59 mmol) was added followed by DIEA (8.22 mL, 47.19 mmol). Additional isobutyl chloroformate (1 mL) was added after 1.5 and 2.5 h. To the cold suspension was then added a ca 0.6M Et2O solution of diazomethane (80 mL) by portions. After 15 min. of stirring, nitrogen was diffused in the solution for 0.5 hr. The solvent was evaporated, the residue taken into EtOAc (75 ml) and the solution washed with 0.5M aqueous citric acid (2×50 mL), 5% aqueous sodium bicarbonate (2×50 mL) and brine (50 mL). After drying (MgSO4) and evaporation of the solvent under reduced pressure, the residue was purified by flash chromatography (20% EtOAc/hexane) to give the title compound (5.52 g) of a yellowish solid.

Provenance & Evidence