反应详情

温度

0 °C

(S)-2-Benzyloxycarbonylamino-3-tert-butoxy-propionic acid (4 g, 0.014 mol) was dissolved in DMF (40 ml). Cyclopentanol (2.54 ml, 0.027 mol) and dimethylaminopyridine (0.165 g, 0.014 mol) were added. The solution was cooled to 0° C. using an ice bath and to it was added N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride (2.73 g, 0.014 mol, 1.05 eq.). The mixture was stirred at 0° C. for 10 minutes and then allowed to warm to r.t. and stirred for a further 18 hours. To the reaction mixture was added water (20-30 ml) followed by EtOAc (40 ml). The layers were separated and the aqueous layer re-extracted with EtOAc (15 ml). The combined organic layers were washed with water (4×20 ml), dried (MgSO4) and the solvent removed in vacuo to give a residue. Purification by column chromatography (1:1 EtOAc/heptane) gave the product as a colourless oil (3.82 g, 78% yield). 1H NMR (300 MHz, CDCl3), δ: 1.15 (9H, s, CH3×3), 1.50-1.90 (8H, m, CH2×4), 3.57 (1H, dd, J=7.4, 1.2 Hz, CH), 3.85 (1H, dd, J=7.4, 1.2 Hz, CH), 4.45 (1H, m, CH), 5.15 (2H, s, CH2), 5.25 (1H, m, CH), 5.65 (1H, d, CH, J=7.6 Hz), 7.30-7.50 (5H, m, ArH×5).

1. temperatureto warm to r.t.
2. stirringstirred for a further 18 hours
3. customThe layers were separated
4. extractionthe aqueous layer re-extracted with EtOAc (15 ml)
5. washThe combined organic layers were washed with water (4×20 ml)
6. dry with materialdried (MgSO4)
7. customthe solvent removed in vacuo
8. customto give a residue
9. customPurification by column chromatography (1:1 EtOAc/heptane)