phosphoric acid in tetrahydrofuran T=45°C; 2 h;

1: 87 percent / pyridine / 6 h / 25 °C 2: 71 percent / NaBH4 / methanol / 0.25 h / 0 °C 3: Ph3P / xylene / 10 h / 25 °C 4: xylene / 24 h / Heating 5: 71 percent / aq. H3PO4 / tetrahydrofuran / 2 h / 45 °C View Scheme

1: 71 percent / NaBH4 / methanol / 0.25 h / 0 °C 2: Ph3P / xylene / 10 h / 25 °C 3: xylene / 24 h / Heating 4: 71 percent / aq. H3PO4 / tetrahydrofuran / 2 h / 45 °C View Scheme

1: Ph3P / xylene / 10 h / 25 °C 2: xylene / 24 h / Heating 3: 71 percent / aq. H3PO4 / tetrahydrofuran / 2 h / 45 °C View Scheme