1: 1.) O3, 2.) DMS / 1.) CH2Cl2, MeOH 2: tetrahydrofuran / Ambient temperature 3: 100 percent / TFA 4: 1.) diphenyl phosphorazidate, Et3N, 2.) aq. HCl / 1.) toluene, reflux, 2.) reflux, 2 h 5: 49 percent / NaOMe / methanol / Ambient temperature 6: 95 percent / tetrahydrofuran / Ambient temperature View Scheme