sodium hydroxide in methanol 1 h; Heating;

dipyridinium dichromate in N,N-dimethyl-formamide T=0 - 25°C;

1.1: 95 percent / LiBr; p-toluenesulfonic acid / 16 h / 25 °C 2.1: 85 percent / pyridine N-oxide; NaHCO3 / toluene / 4 h / Heating 3.1: n-BuLi / tetrahydrofuran; hexane / 1.5 h / -20 °C 3.2: 61 percent / tetrahydrofuran; hexane / 2 h / Heating 4.1: 543 mg / Et2Zn / CH2Cl2 / 49 h / -20 - 25 °C 5.1: 310 mg / HCl / methanol / 16 h / 25 °C 6.1: 69 percent / pyridinium dichromate / dimethylformamide / 0 - 25 °C View Scheme

1.1: n-BuLi / tetrahydrofuran; hexane / 1.5 h / -20 °C 1.2: 61 percent / tetrahydrofuran; hexane / 2 h / Heating 2.1: 543 mg / Et2Zn / CH2Cl2 / 49 h / -20 - 25 °C 3.1: 310 mg / HCl / methanol / 16 h / 25 °C 4.1: 69 percent / pyridinium dichromate / dimethylformamide / 0 - 25 °C View Scheme

1: 543 mg / Et2Zn / CH2Cl2 / 49 h / -20 - 25 °C 2: 310 mg / HCl / methanol / 16 h / 25 °C 3: 69 percent / pyridinium dichromate / dimethylformamide / 0 - 25 °C View Scheme

1.1: 85 percent / pyridine N-oxide; NaHCO3 / toluene / 4 h / Heating 2.1: n-BuLi / tetrahydrofuran; hexane / 1.5 h / -20 °C 2.2: 61 percent / tetrahydrofuran; hexane / 2 h / Heating 3.1: 543 mg / Et2Zn / CH2Cl2 / 49 h / -20 - 25 °C 4.1: 310 mg / HCl / methanol / 16 h / 25 °C 5.1: 69 percent / pyridinium dichromate / dimethylformamide / 0 - 25 °C View Scheme

1: Pd(OAc)2 / 0.33 h / Ambient temperature 2: aq. NaOH / methanol / 1 h / Heating View Scheme

in diethyl ether