C1(P(C2C=CC=CC=2)C2C=CC=CC=2)C=CC=CC=1.[C:20]([Br:24])(Br)(Br)[Br:21].[CH3:25][Si:26]([CH3:32])([CH3:31])[CH2:27][CH2:28][CH:29]=O>C(Cl)Cl.CCOCC>[Br:21][C:20]([Br:24])=[CH:29][CH2:28][CH2:27][Si:26]([CH3:32])([CH3:31])[CH3:25]This known compound was prepared by a modification of the procedure in Piers, E.; Gavai, A. V. J. Org. Chem. 1990, 55, 2374. To a flame dried flask was added dry CH2Cl2 (150 mL) and triphenylphosphine (16 g, 61.2 mmol). The temperature was lowered to 0° C. and CBr4 (10.15 g, 30.6 mmol) was added portionwise. After 30 min, a solution of 3-trimethylsilylpropanal (2.0 g, 15.3 mmol) in dry CH2Cl2 (20 ml) was added. After 1 h at 0° C., the reaction was diluted with ether and filtered through celite. The celite was rinsed with ether (4×50 mL) and the combined ether solution was extracted with H2O (100 mL), saturated NaHCO3 (100 mL), saturated NH4Cl (100 mL) and brine (100 mL). The organic layer was dried (MgSO4), filtered and evaporated to give a crude white solid. The solid residue was washed with pentane. The pentane solution was concentrated and the oily residue was chromatographed on silica gel (pentane 100%) to give (4,4-dibromo-but-3-enyl)trimethylsilane as a clear oil weighing 3.7 g. 1H NMR showed 27% contamination by remaining pentane which gives a corrected yield of 62%: IR (neat, cm-1) 2953, 2922, 2898, 1620, 1443, 1413, 1249, 1176, 1034, 986, 859, 837; 1H NMR (300 MHz, CDCl3) δ0.03 (s, 9H), 0.62-0.67 (m, 2H), 2.06-2.14 (m, 2H), 6.41 (t, J=7 Hz 1H); 13C NMR (75 MHz, CDCl3) δ-1.9, 15.1, 27.7, 87.5, 141.2.
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