Diisopropylethylamine → Boc-Asp(NEt2)-OBzl

Participants

Reaction Steps

BOP (2.20 g, 5.0 mmol) was added under N2 to a cooled (0°) solution of Boc-Asp-OBzl (1.90 g, 4.6 mmol) in CH2Cl2 (50 ml). After 3 min NHEt2.HCl (0.55 g, 5.0 mmol) and DIPEA (2.4 ml, 1.38 mmol) were added. The resultant solution was stirred at 20-22° for 18 h. The solution was washed with 10% aqueous citric acid (2×), 10% aqueous NaHCO3 (2×) and brine (2×). The organic layer was dried (MgSO4) and concentrated to give an oil. After SiO2 chromatography of the oil using hexane-EtOAc (7:3) as the eluent, Boc-Asp(NEt2)-OBzl (1.55 g, 89%) was obtained as an oil. Under a N2 atmosphere, a solution of the latter compound (1.55 g, 4.09 mmol) in MeOH (100 ml) was mixed with 5% Pd/C (155 mg). The mixture was shaken on a Parr apparatus under H2 (50 psi) for 90 min. The mixture was filtered through a 45 m membrane and the filtrate concentrated to give Boc-Asp(NEt2)—OH (1.15 g, 98%) as an oil. The structure of the product was confirmed by NMR.

Provenance & Evidence