反应详情

温度

0 °C

Alcohol 29 (12.3 g, 74.2 mmol) is dissolved in dry DMF and cooled to 0° C. under N2. Solid N-bromosuccinimide (NBS, 14.77 g, 83.0 mmol) is added in small portions (the yellow color is allowed to dissipate between additions) over 1.5 h. After the addition is complete, stirring at 0° C. is continued for 30 min. The mixture is then poured into water and extracted with EtOAc (3×). The organic phase is washed with water (1×) and brine (1×), dried (MgSO4), filtered, and evaporated. The residue is dissolved in EtOAc/CH2Cl2 and diluted with hexane to afford 30 as white crystals, mp 139-141° C. (12.7 g, 70%). Concentration of the mother liquor gives two more crops (1.2 and 1.0 g) of crystals, bringing the total to 14.9 g (82%). 1H NMR (acetone-d6, 2.05 ppm) 8.43 (S,1), 7.34 (d, 1, J=8.7), 7.01 (d, 1, J=2.7), 6.64 (dd, 1, J=8.7, 2.8), 2.89 (s,2), 1.21 (s,6); 13C NMR (acetone-d6, 20.83 ppm) 147.90, 130.98, 124.56, 111.34, 107.05, 106.19, 62.35, 39.59, 20.76; MS (EI, eE=70 eV) m/z 246/244 (M+), 231/229, 201, 188/186, 163, 150, 131, 108, 107, 91, 77, 63, 59 (base peak), 51, 43; Anal. Calcd for C10H13BrO2 (MW=245.1) : C,49.00 H,5.35. Found: C,49.03 H,5.20.

1. customover 1.5 h
2. additionAfter the addition
3. extractionextracted with EtOAc (3×)
4. washThe organic phase is washed with water (1×) and brine (1×)
5. dry with materialdried (MgSO4)
6. filtrationfiltered
7. customevaporated
8. dissolutionThe residue is dissolved in EtOAc/CH2Cl2
9. additiondiluted with hexane