反应详情

温度

55 °C

To a 250 mL round bottom flask were added (R)-4-benzyl-3-((2R,3R,4S)-4-(benzyloxy)-3-hydroxy-2-(4-methylbenzyl)pentanoyl)oxazolidin-2-one (11.2 g, 23 mmol) and anhydrous THF (145 mL). The solution was sparged with N2 for 5 min and then tris(dibenzylideneacetone)-dipalladium (0) (Pd2(dba)3; 2.10 g, 2.3 mmol) and 1,1′-bis(diphenylphosphino)ferrocene (dppf; 2.55 g, 4.59 mmol) were added, and the resulting dark solution was sparged with N2 for an additional 5 minutes. The reaction mixture was warmed to 55° C. under N2 and treated with a solution of tert-butyl (2-methylallyl)carbonate (7.9 g, 45.9 mmol) in THF (5 mL). The dark mixture was stirred at 55° C. for 1 h and then cooled to room temperature. The reaction mixture was filtered through paper, rinsing with CH2Cl2, and the filtrate was evaporated to give a dark oil. The oil was partially purified by flash chromatography (SiO2, 0→30% acetone/hexanes) to give (R)-4-benzyl-3-((2R,3R,4S)-4-(benzyloxy)-3-((2-methylallyl)oxy)-2-(4-methylbenzyl)pentanoyl)oxazolidin-2-one (9.36 g) as a yellow oil that is contaminated with dibenzylideneacetone (dba): 1H NMR (400 MHz, CDCl3) δ 7.22 (m, 10H), 7.02 (d, J=7.8 Hz, 2H), 6.87 (m, 2H), 5.06 (m, 1H), 4.91 (s, 1H), 4.77 (ddd, J=11.7, 9.3, 4.7 Hz, 1H), 4.64 (d, J=11.9 Hz, 1H), 4.31 (d, J=11.9 Hz, 1H), 4.16 (s, 2H), 3.96 (m, 1H), 3.74 (dd, J=9.2, 7.1 Hz, 1H), 3.62 (p, J=6.1 Hz, 1H), 3.41 (m, 2H), 2.85 (m, 2H), 2.70 (dd, J=13.7, 3.5 Hz, 1H), 2.26 (s, 3H), 2.17 (s, 3H), 1.49 (dd, J=13.7, 10.6 Hz, 1H), 1.34 (d, J=6.1 Hz, 3H); ESIMS m/z 565 ([M+Na]+).

1. customThe solution was sparged with N2 for 5 min
2. customthe resulting dark solution was sparged with N2 for an additional 5 minutes
3. temperaturecooled to room temperature
4. filtrationThe reaction mixture was filtered through paper
5. washrinsing with CH2Cl2
6. customthe filtrate was evaporated
7. customto give a dark oil
8. customThe oil was partially purified by flash chromatography (SiO2, 0→30% acetone/hexanes)