1: 97 percent / aq. NaHCO3 / acetone / 2 h / Ambient temperature 2: 1.) O3, 2.) Me2S / 1) CH2Cl2, MeOH, dry ice/acetone bath, 6 psi O2; 2) CH2Cl2, CH3OH, cooling --> rt, 20 h 3: 80 percent / Et3SiH, boron trifluoride diethyl etherate / CH2Cl2 / 2 h / -78 °C View Scheme