反应详情

To a magnetically stirred solution of DMAP (3.22 g, 26.3 mmol) and MNBA (2.07 g, 6.02 mmol) in anhydrous toluene (750 mL) was added a solution of (S)-2-((tert-butoxycarbonyl)amino)-3-(((2S,3R,4S)-4-hydroxy-3-isobutoxy-2-(4-methylbenzyl)pentyl)oxy)-propanoic acid (1.76 g, 3.76 mmol) in anhydrous toluene (60 mL) dropwise over 5.5 h (syringe pump), and the resulting turbid mixture was stirred for 16 h. The reaction mixture was filtered through paper and the filtrate was concentrated to a pale yellow solid which was purified by flash chromatography (SiO2, 0→30% acetone/hexanes) to give tert-butyl((3S,7S,8R,9S)-8-isobutoxy-9-methyl-7-(4-methylbenzyl)-2-oxo-1,5-dioxonan-3-yl)carbamate (1.48 g, 87%) as a white foam: 1H NMR (400 MHz, CDCl3) δ 7.09 (d, J=8.2 Hz, 2H), 7.06 (d, J=8.2 Hz, 2H), 5.14 (d, J=8.2 Hz, 1H), 4.95 (dq, J=9.2, 6.4 Hz, 1H), 4.59 (q, J=7.3 Hz, 1H), 3.87 (dd, J=11.5, 7.3 Hz, 1H), 3.44 (t, J=7.4 Hz, 2H), 3.32 (tdd, J=16.8, 10.6, 5.2 Hz, 3H), 3.10 (dd, J=10.4, 6.6 Hz, 2H), 2.31 (s, 3H), 2.24 (t, J=12.7 Hz, 1H), 1.88 (dq, J=13.2, 6.6 Hz, 2H), 1.47 (d, J=6.4 Hz, 3H), 1.41 (s, 9H), 0.95 (d, J=6.7 Hz, 6H); 13C NMR (101 MHz, CDCl3) δ 172.24, 154.95, 136.81, 135.52, 129.10, 129.01, 84.66, 80.02, 79.21, 75.57, 72.86, 72.48, 52.97, 47.40, 34.56, 29.17, 28.27, 21.01, 19.48, 18.80; ESIMS m/z 473 ([M+Na]+).

1. filtrationThe reaction mixture was filtered through paper
2. concentrationthe filtrate was concentrated to a pale yellow solid which
3. customwas purified by flash chromatography (SiO2, 0→30% acetone/hexanes)