1: 96 percent / DBU / CH2Cl2 / -15 deg C, 15 min then room temp., 15 min 2: 1.) CuI; 2.) aq. NaOH / 1.) THF, -30 deg C; 2.) EtOH, reflux, 5 h View Scheme

1,8-diazabicyclo[5.4.0]undec-7-ene in dichloromethane -15 deg C, 15 min then room temp., 15 min;

With  ozone in  dichloromethane T=-78°C;