1: With pyridinium p-toluenesulfonate; orthoformic acid triethyl ester in 1,2-dichloro-ethane T=20 - 60°C; 5.33333 h; 2: With methanol; potassium carbonate in ethylene glycol dimethyl ether T=20°C; 18 h;

1.1: triethyl orthoformate; pyridinium p-toluenesulfonate / 1,2-dichloro-ethane / 5 h / 60 °C 1.2: K2CO3 / methanol; 1,2-dimethoxy-ethane / 20 °C 2.1: 76 percent / Dess-Martin periodinane / CH2Cl2 / 2 h / 20 °C 3.1: 90 percent / L-Selectride / tetrahydrofuran / -78 °C 4.1: 80 percent / DMAP / CH2Cl2 / 20 °C 5.1: 80 percent / H2 / Pd(OH)2/C / methanol; tetrahydrofuran / 6 h / 20 °C View Scheme