1: 1.) O3, 2.) Me2S / 1.) MeOH, CH2Cl2, -78 deg C, 2.) MeOH, a) -78 deg C, 1 h, b) RT, 1 h 2: 91 percent / ammonium formate, AcOH / Pd / 4 h / Heating 3: 90 percent / 0.1 N NaOH / ethanol / 9 h / Ambient temperature 4: 85 percent / Et3N, bis(2-oxo-3-oxazolidinyl)phosphinic chloride / CH2Cl2 / 1 h / Ambient temperature View Scheme

1: 1.) O3, 2.) Me2S / 1.) MeOH, CH2Cl2, -78 deg C, 2.) MeOH, a) -78 deg C, 1 h, b) RT, 1 h 2: 91 percent / ammonium formate, AcOH / Pd / 4 h / Heating 3: 90 percent / 0.1 N NaOH / ethanol / 9 h / Ambient temperature View Scheme