反应详情

温度

20 °C

A mixture of alcohol 70 (50 mg, 0.20 mmol), N-Boc Valine (44 mg, 0.20 mmol), DCC (46 mg, 0.22 mmol) and DMAP (2.5 mg, 0.02 mmol) in DCM (10 mL) was stirred at 20° C. for 1 h. The solvent was evaporated and the residue purified by chromatography, eluting with a gradient (0-5%) of MeOH/DCM, to give the crude ester, which was suspended in DCM (2 mL) and filtered to remove urea by-products. The filtrate was concentrated to give crude ester 310 (84 mg, 93%) as a pale-brown gum: 1H NMR δ 8.27 (s, 1H, H-9); 7.76 (s, 1H, H-5), 4.96-5.03 (m, 1H, CH), 4.28 (t, J=6.5 Hz, 2H, CH2O), 3.08-3.16 (m, 6H, H-6, H-8, CH2), 2.21-2.31 (m, 4H, H-7, CH2), 2.08-2.17 (br m, 1H, CH), 1.46 [s, 9H, C(CH3)3], 0.97 (d, J=6.9 Hz, 3H, CH3), 0.91 (d, J=6.9 Hz, 3H, CH3), NH not observed; HRMS calcd for C23H32N4O5 (M+) m/z 444.2373, found 444.2382.

1. customThe solvent was evaporated
2. customthe residue purified by chromatography
3. washeluting with a gradient (0-5%) of MeOH/DCM
4. customto give the crude ester, which
5. filtrationfiltered
6. customto remove urea by-products
7. concentrationThe filtrate was concentrated