1: CBrCl3, 2-mercaptopyridine N-oxide sodium salt, 4-(dimethylamino)pyridine / 1 h / 80 °C / Irradiation 2: aq. AcOH, conc. HCl / 3 h / Ambient temperature 3: 100 percent / KOH / methanol / 3 h / Ambient temperature 4: 84 percent / propan-2-ol / 1.) 70 deg C, 9 h, 2.) r.t., 16 h View Scheme

1: CBrCl3, 2-mercaptopyridine N-oxide sodium salt, 4-(dimethylamino)pyridine / 1 h / 80 °C / Irradiation 2: aq. AcOH, conc. HCl / 3 h / Ambient temperature 3: 100 percent / KOH / methanol / 3 h / Ambient temperature 4: 84 percent / propan-2-ol / 1.) 70 deg C, 9 h, 2.) r.t., 16 h 5: 86 percent / trifluoroacetic acid / 1 h / Ambient temperature View Scheme

1: CBrCl3, 2-mercaptopyridine N-oxide sodium salt, 4-(dimethylamino)pyridine / 1 h / 80 °C / Irradiation 2: aq. AcOH, conc. HCl / 3 h / Ambient temperature 3: 100 percent / KOH / methanol / 3 h / Ambient temperature 4: 84 percent / propan-2-ol / 1.) 70 deg C, 9 h, 2.) r.t., 16 h 5: 86 percent / trifluoroacetic acid / 1 h / Ambient temperature 6: 48 percent / 1-hydroxybenzotriazole hydrate, dicyclohexylcarbodiimide, N-ethylmorpholine / tetrahydrofuran / 64 h / Ambient temperature 7: H2 / 10percent Pd/C / ethanol / 16 h 8: 1-hydroxybenzotriazole hydrate, dicyclohexylcarbodiimide, N-ethylmorpholine / tetrahydrofuran / 16 h / Ambient temperature View Scheme

1: CBrCl3, 2-mercaptopyridine N-oxide sodium salt, 4-(dimethylamino)pyridine / 1 h / 80 °C / Irradiation 2: aq. AcOH, conc. HCl / 3 h / Ambient temperature 3: 100 percent / KOH / methanol / 3 h / Ambient temperature 4: 84 percent / propan-2-ol / 1.) 70 deg C, 9 h, 2.) r.t., 16 h 5: 86 percent / trifluoroacetic acid / 1 h / Ambient temperature 6: 48 percent / 1-hydroxybenzotriazole hydrate, dicyclohexylcarbodiimide, N-ethylmorpholine / tetrahydrofuran / 64 h / Ambient temperature View Scheme

Multi-step reaction with 4 steps 1: NaBH4 / ethanol / 1 h / -15 - -10 °C2: 80 percent / TsOH*H2O / 1.) r.t., 24 h, 2.) 50 deg C, 7 h3: 100 percent / 1 M aq. NaOH / ethanol / 18 h / Ambient temperature4: (COCl)2, DMF / toluene / 1 h