1: 83 percent / powdered KOH / diethyl ether / -10 deg C, 20 min, then -10 deg C, 1 h 2: 55 percent / LiBr / acetone / overnight in darkened flask 3: 81 percent / powdered zinc / methanol / 5 h / Heating View Scheme

oxalyl dichloride; dimethyl sulfoxide; triethylamine in dichloromethane -60 deg C, 2 min, then -60 deg C, 15 min;

1: 71 percent / 1.) oxalyl chloride, DMSO; 2.) Et3 N / CH2Cl2 / -60 deg C, 2 min, then -60 deg C, 15 min 2: 88 percent / Zn(BH4)2 / diethyl ether / 1 h / 0 °C 3: 74 percent / CBr4 / tetrahydrofuran; hexamethylphosphoric acid triamide / -78 °C / to warm up to Rt over 12 h 4: nBu3SnLi / tetrahydrofuran; hexane / 1 h / -20 - -15 °C / study of the sterochemistry of the conversion of α-haloepoxides with various trialkyl stannate, mechanism of the elimination reaction is discussed View Scheme