反应详情

To a suspension of 1,4-dimethylpiperazine-2,3-dione (2.08 g, 1.46×10−2 mol) in 50 ml of dry Et2O was added 3,7-dimethyloctyl lithium (0.45M solution in Et2O, 65 ml, 2.9×10−2 mol, freshly prepared from 3,7-dimethyloctyl bromide and lithium) by a syringe. After 40 min of stirring at room temperature under N2, the solution was hydrolyzed with 100 ml of 10% HCl and extracted with CHCl3. The combined organic layers were washed with saturated aqueous NaHCO3 and dried over Na2SO4. The product was chromatographed on silica gel with 3:1 hexane:CHCl3 as the eluent. Yield=4.446 g (91% based on 65 ml of 0.45M 3,7-dimethyloctyl lithium in Et2O). 1H NMR (250 MHz, CDCl3): δ 2.69-2.78 (m, 4H, —CH2CO), 1.06-1.65 (m, 20H, (CH3)2CHCH2CH2CH2CH(CH3)CH2CH2CO), 0.87 (d, 6H, J=9.0 Hz, —CH3), 0.86 (d, 12H, J=9.5 Hz, —CH3). CI MS m/z: 338.3175 (M+) (calcd 338.318).

1. extractionextracted with CHCl3
2. washThe combined organic layers were washed with saturated aqueous NaHCO3
3. dry with materialdried over Na2SO4
4. customThe product was chromatographed on silica gel with 3:1 hexane