BOC-ASN-OBZL

The compound was prepared according to BIOORG. MED. CHEM., 6 (1998) 1185-1208. N- [ (1, L-DIMETHYLETHOXYCARBONYL) AMINO]-L-ASPARAGINE (20.7 g, 89.1 mmol, 1 eq. ), of Step 1, was dissolved in methanol (500 ml) and cesium carbonate (15.97 g, 49 mmol, 0.55 eq. ) was added. The solvent was evaporated to give a white solid that was dissolved in N, N-dimethylformamide (200 ml). To the suspension, benzyl bromide (11.6 ml, 98 mmol, 1.1 eq. ) was added dropwise and the mixture was stirred overnight. The solvent was reduced under reduced pressure, water (300 ml) was added and the mixture extracted with ethyl acetate (200 ml), washed with brine (50ml) and the solvent removed under reduced pressure to give a crude that was suspended in n-hexane (160 ml), filtered and dried under vacuum to give 14. 68 g of white solid. Yield 51percent. Analytical data: m. p. 113°-115°C. 'H NMR (DMSO-d6) 7.35 (6H, M) ; 7.13 (1H, d, J=7.9 Hz) ; 6.94 (1H, br s); 5.10 (2H, s); 4.39 (1H, q, J=7. 4 Hz); 2.6-2. 4 (2H, M) ; 2.03 (2H, t, J=7. 3); 1.37 (9H, s).General procedure: To a stirred solution of N-protected-L-asparagin 1a-c (0.10 mmol) and alcohol or amine 2a-n (0.12 mmol) inDCM (5 mL), EDC.HCl (0.30 mmol) and DMAP (0.02 mmol) were added at 0 oC. This reaction mixture was stirred for 12h at room temperature. Then the reaction mixture was poured in H2O (10 mL) and extracted with DCM (20 mL). The organic phase was separated, dried, and subjected to flash column chromatography (EtOAc–hexane, 1: 4) to afford the desired compounds as white solids.