Ammonia → HCID 59909900, compound

Participants

Reaction Steps

N,O-Bis-Boc-(S)-tyrosine from example 64 (5.00 g, 13.11 mmol) was dissolved in THF (20 mL), the solution stirred under an argon atmosphere and cooled in an ice bath. DIEA (5.70 mL, 32.7 mmol) was added followed by isobutylchloroformate (2.55 mL, 19.6 mmol). After 45 min a solution of 2M ammonia in isopropanol (39.3 mL, 78.6 mmol) was added and the mixture stirred at room temperature for 18 h. The solvent was evaporated, the residue taken in EtOAC (100 mL), washed with 5% aqueous citric acid (2×50 mL), 5% aqueous sodium bicarbonate (2×50 mL) and brine. After drying (MgSO4) and evaporation of the solvent, the residue was dissolved in chloroform (15 mL), stirred vigorously and Et2O (150 mL) was added. The suspension was stirred for 20 min. then the solid filtered and air dried to yield 3.10 g (62%) of the title compound.

Provenance & Evidence