magnesium sulfate in toluene T=20°C;

magnesium; ethylene dibromide in tetrahydrofuran to Mg turnings and THF 1,2-dibromoethane followed by α-bromostyrene in THF were added, stirred at 80°C for 30 min, cooled to -78°C, soln. B(OMe)3 in THF was added dropwise and stirred at -78°C for 1 h and overnight at r.t.; react. mixt. was treated with aq. HCl, extracted with Et2O, evapd., dissolved in toluene, 1,3-propanediol was added and stirred with MgSO4 overnight at room temp., soln. was filtered, dried over MgSO4 and distilled under reduced pressure;

1.1: Mg; 1,2-dibromoethane / tetrahydrofuran / 0.5 h / 80 °C 1.2: tetrahydrofuran / 1 h / -78 °C 2.1: 66 percent / MgSO4 / toluene / 20 °C View Scheme