2-(oxan-2-yloxy)acetaldehyde

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-(Tetrahydro-2-pyranyloxy)-propene (20 g, 0.14 mole) was dissolved in dichloro-methane (250 ml). Ozone was bubbled into the solution at -78° C. for about 3 hours until the solution turned blue. Warmed to room temperature and zinc powder (20 g) was added. Acetic acid (20 ml) and water (3 ml) were added slowly with cooling in ice bath. The reaction mixture was further stirred for 2 hours at room temperature and then extracted with dichloromethane. The extract was washed with sodium bicarbonate aqueous solution (10 ml×2), dried over anhydrous magnesium sulfate, concentrated. The crude product was distilled under vacuum (62°-64° C./2 mmHg) gave colorless oil (13.72 g, 68%). 2-(Tetra-hydro-2-pyranyloxy)-propene was directly prepared from allyl alcohol and dihydropyran in the presence of a small amount of p-toluenesulfonic acid.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Acetylene gas was bubbled into tetrahydrofuran (30 ml) for 30 minutes. Ethyl magnesium bromide (25 ml) was added. 2-(Tetrahydro-2-pyranyloxy)-acetaldehyde (5.0 g, 0.035 mole) in tetrahydrofuran (25 ml) was then added. The reaction mixture was warmed to room temperature and stirred overnight. Saturated ammonium chloride aqueous solution (30 ml) was added to quench the unreacted acetylide and extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate, concentrated and separated by silica gel chromatography eluted with n-hexane/ethyl acetate (5:2) to give colorless oil (4.5 g, 76%). Acetylene gas was bubbled into tetrahydrofuran (30 ml) for 30 minutes Ethyl magnesium bromide (25 ml) was added to quench the unreacted acetylide extracted with ethyl acetate The extract was dried over anhydrous magnesium sulfate concentrated separated by silica gel chromatography eluted with n-hexane/ethyl acetate (5:2)

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 2-(Tetrahydro-2-pyranyloxy)-propene (20 g, 0.14 mole) was dissolved in dichloro-methane (250 ml). Ozone was bubbled into the solution at -78° C. for about 3 hours until the solution turned blue. Warmed to room temperature and zinc powder (20 g) was added. Acetic acid (20 ml) and water (3 ml) were added slowly with cooling in ice bath. The reaction mixture was further stirred for 2 hours at room temperature and then extracted with dichloromethane. The extract was washed with sodium bicarbonate aqueous solution (10 ml×2), dried over anhydrous magnesium sulfate, concentrated. The crude product was distilled under vacuum (62°-64° C./2 mmHg) gave colorless oil (13.72 g, 68%). 2-(Tetra-hydro-2-pyranyloxy)-propene was directly prepared from allyl alcohol and dihydropyran in the presence of a small amount of p-toluenesulfonic acid.

Conditions: temp:0.00; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: Acetylene gas was bubbled into tetrahydrofuran (30 ml) for 30 minutes. Ethyl magnesium bromide (25 ml) was added. 2-(Tetrahydro-2-pyranyloxy)-acetaldehyde (5.0 g, 0.035 mole) in tetrahydrofuran (25 ml) was then added. The reaction mixture was warmed to room temperature and stirred overnight. Saturated ammonium chloride aqueous solution (30 ml) was added to quench the unreacted acetylide and extracted with ethyl acetate. The extract was dried over anhydrous magnesium sulfate, concentrated and separated by silica gel chromatography eluted with n-hexane/ethyl acetate (5:2) to give colorless oil (4.5 g, 76%). Acetylene gas was bubbled into tetrahydrofuran (30 ml) for 30 minutes Ethyl magnesium bromide (25 ml) was added to quench the unreacted acetylide extracted with ethyl acetate The extract was dried over anhydrous magnesium sulfate concentrated separated by silica gel chromatography eluted with n-hexane/ethyl acetate (5:2)