oxalyl dichloride; dimethyl sulfoxide; triethylamine in dichloromethane T=-78 - 20°C; Swern oxidation;

1: With ozone in dichloromethane T=-78°C; 2: With dimethylsulfide in dichloromethane T=20°C; 3: With 1,8-diazabicyclo[5.4.0]undec-7-ene in dichloromethane Further stages.;

1: 89 percent / K2CO3 / dimethylformamide / 20 °C 2: 91 percent / RuCl2(Cy3P)2=CHPh / CH2Cl2 / 3 h / 20 °C 3: 89 percent / 18-crown-6; oxone; aq. NaHCO3 / acetone; CH2Cl2 / 16 h / 0 °C 4: 89 percent / KHMDS / toluene / 1 h / -60 °C 5: 98 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -78 - 20 °C View Scheme

1: 89 percent / 18-crown-6; oxone; aq. NaHCO3 / acetone; CH2Cl2 / 16 h / 0 °C 2: 89 percent / KHMDS / toluene / 1 h / -60 °C 3: 98 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -78 - 20 °C View Scheme

1: 89 percent / KHMDS / toluene / 1 h / -60 °C 2: 98 percent / (COCl)2; DMSO; Et3N / CH2Cl2 / -78 - 20 °C View Scheme