1,8-diazabicyclo[5.4.0]undec-7-ene in dichloromethane T=-78°C; 3 h;

Grubb's 2nd generation catalyst in toluene T=80°C; 1 h; Inert atmosphere;

1: 81 percent / pyridinium dichromate, 4A molecular sieves / CH2Cl2 / 4 h 2: 93 percent / DBU / CH2Cl2 / 3 h / -78 °C View Scheme

1: 1.) O3, 2.) thiourea / 1.) MeOH, -78 deg C 2: 1.) n-BuLi / 1.) THF, -78 deg C, 5 min., 2.) a) THF, -78 deg C, 5 min., b) AcOH-THF, -78 deg C -> r.t. 3: 99 percent / conc. H2SO4 / acetonitrile; H2O / 65 °C 4: 81 percent / pyridinium dichromate, 4 Angstroem sieves / CH2Cl2 / Ambient temperature 5: 1.) DBU, 2.) AcOH-THF / 1.) CH2Cl2, -78 deg C, 2.) -78 deg C to r.t. View Scheme

1: 1.) n-BuLi / 1.) THF, -78 deg C, 5 min., 2.) a) THF, -78 deg C, 5 min., b) AcOH-THF, -78 deg C -> r.t. 2: 99 percent / conc. H2SO4 / acetonitrile; H2O / 65 °C 3: 81 percent / pyridinium dichromate, 4 Angstroem sieves / CH2Cl2 / Ambient temperature 4: 1.) DBU, 2.) AcOH-THF / 1.) CH2Cl2, -78 deg C, 2.) -78 deg C to r.t. View Scheme

1: 99 percent / conc. H2SO4 / acetonitrile; H2O / 65 °C 2: 81 percent / pyridinium dichromate, 4 Angstroem sieves / CH2Cl2 / Ambient temperature 3: 1.) DBU, 2.) AcOH-THF / 1.) CH2Cl2, -78 deg C, 2.) -78 deg C to r.t. View Scheme

Multistep reaction;