2-methoxy-3,4-dihydro-2H-pyran

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

Procedure: 85 parts of benzoin are reacted with 68.4 parts (50% molar excess) of 2-methoxy-2,3-dihydro-4H-pyran in 120 parts by volume of benzene, analogously to Example 1. The resulting benzoin 2-methoxy-tetrahydropyranyl ether, obtained in a yield of 87.4% of theory, boils at 195° to 200° C/0.3 mm Hg and has the following structure: ##STR7## NMR spectrum (in CDCl3): δ = 1.0 -2.4 (multiplet, 6 protons)

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

Procedure: 85 parts of benzoin are reacted with 68.4 parts (50% molar excess) of 2-methoxy-2,3-dihydro-4H-pyran in 120 parts by volume of benzene, analogously to Example 1. The resulting benzoin 2-methoxy-tetrahydropyranyl ether, obtained in a yield of 87.4% of theory, boils at 195° to 200° C/0.3 mm Hg and has the following structure: ##STR7## NMR spectrum (in CDCl3): δ = 1.0 -2.4 (multiplet, 6 protons)

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

Procedure: Borane-THF 1M (14.6 ml, 14.6 mmol) was added slowly to an ice cooled solution of 3,4-dihydro-2-methoxy-2H-pyran (55.0 g, 44 mmol) in THF (15 ml). The ice bath was removed and the reaction was stirred at room temperature for 1 h, cooled to 0° C. and 3 N sodium hydroxide (14.6 ml) was added followed with 30% hydrogen peroxide (9 ml). This was allowed to stir for 4 hs warming to room temperature. The reaction was extracted with ethyl acetate (2×50 ml). The combined organic layer was washed with brine, dried over magnesium sulfate and concentrated to give 6-methoxytetrahydro-2H-pyran-3-ol (4.2 g, 72%) as an oil. The ice bath was removed cooled to 0° C. 3 N sodium hydroxide (14.6 ml) was added to stir for 4 hs warming to room temperature The reaction was extracted with ethyl acetate (2×50 ml) The combined organic layer was washed with brine dried over magnesium sulfate concentrated

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

Procedure: Borane-THF 1M (14.6 ml, 14.6 mmol) was added slowly to an ice cooled solution of 3,4-dihydro-2-methoxy-2H-pyran (55.0 g, 44 mmol) in THF (15 ml). The ice bath was removed and the reaction was stirred at room temperature for 1 h, cooled to 0° C. and 3 N sodium hydroxide (14.6 ml) was added followed with 30% hydrogen peroxide (9 ml). This was allowed to stir for 4 hs warming to room temperature. The reaction was extracted with ethyl acetate (2×50 ml). The combined organic layer was washed with brine, dried over magnesium sulfate and concentrated to give 6-methoxytetrahydro-2H-pyran-3-ol (4.2 g, 72%) as an oil. The ice bath was removed cooled to 0° C. 3 N sodium hydroxide (14.6 ml) was added to stir for 4 hs warming to room temperature The reaction was extracted with ethyl acetate (2×50 ml) The combined organic layer was washed with brine dried over magnesium sulfate concentrated

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 152 g. (1.0 mole) benzaldehyde dimethyl acetal was combined with 3 g. ZnCl2. While stirring and cooling to 25° C., 114 g. (1 mole) 2-methoxy-2,3-dihydro-4H-pyran was added. After stirring for an hour, the catalyst was neutralized by the addition of 15 g. potassium carbonate in 30 ml. water. The mixture was then extracted with ether and the combined ether extracts were washed with water and dried over sodium sulfate. After the removal of the solvent, the residue was distilled in vacuo to give the title compound; b.p. 120°-128° C. (0.6 mm). Yield: 243 g. (91%). After stirring for an hour the catalyst was neutralized by the addition of 15 g The mixture was then extracted with ether the combined ether extracts were washed with water dried over sodium sulfate After the removal of the solvent the residue was distilled in vacuo

Conditions: temp:25.01; pressure:0.00; stir:; See reaction.notes.procedure_details.

Procedure: 152 g. (1.0 mole) benzaldehyde dimethyl acetal was combined with 3 g. ZnCl2. While stirring and cooling to 25° C., 114 g. (1 mole) 2-methoxy-2,3-dihydro-4H-pyran was added. After stirring for an hour, the catalyst was neutralized by the addition of 15 g. potassium carbonate in 30 ml. water. The mixture was then extracted with ether and the combined ether extracts were washed with water and dried over sodium sulfate. After the removal of the solvent, the residue was distilled in vacuo to give the title compound; b.p. 120°-128° C. (0.6 mm). Yield: 243 g. (91%). After stirring for an hour the catalyst was neutralized by the addition of 15 g The mixture was then extracted with ether the combined ether extracts were washed with water dried over sodium sulfate After the removal of the solvent the residue was distilled in vacuo

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

Procedure: 85 parts of benzoin are reacted with 68.4 parts (50% molar excess) of 2-methoxy-2,3-dihydro-4H-pyran in 120 parts by volume of benzene, analogously to Example 1. The resulting benzoin 2-methoxy-tetrahydropyranyl ether, obtained in a yield of 87.4% of theory, boils at 195° to 200° C/0.3 mm Hg and has the following structure: ##STR7## NMR spectrum (in CDCl3): δ = 1.0 -2.4 (multiplet, 6 protons)