Method of preparing optically pure (R)- or (S)- tetrahydrofuranyl ketone
View Patent ↗Disclosed is a method of preparing an optically pure (R)- or (S)-tetrahydrofuranyl ketone. By such a method, (R)- or (S)-2-tetrahydrofuran amide is converted to (R)- or (S)-2-tetrahydrofuran nitrile through dehydration in the presence of a dehydrating agent and an amine base. Then, thus prepared (R)- or (S)-2-tetrahydrofuran nitrile is nucelophilic addition-reacted with a nucleophile, followed by hydrolyzing, thereby produce (R)- or (S)-tetrahydrofuranyl ketone having high optical purity, while minimizing production of other by-products.
1. A method of preparing an optically pure (R)-tetrahydrofuranyl ketone, which comprises the following steps of:
dehydrating (R)-2-tetrahydrofuran amide, represented by the following chemical formula 1a, in the presence of a dehydrating agent and an amine base at 50 to 100° C. for 2 to 6 hours to obtain (R)-2-tetrahydrofuran nitrile represented by the following chemical formula 2a;
nucelophilic addition-reacting (R)-2-tetrahydrofuran nitrile with a nucleophile in an organic solvent at the temperature range of −80 to 100° C. for 10 minutes to 4 hours, followed by hydrolyzing by use of aqueous acidic solution to produce (R)-tetrahydrofuranyl ketone represented by the following chemical formula 3a; and
recovering the resulting product obtained from the previous step:
wherein, R is a straight-chained or branched, saturated or unsaturated aliphatic alkyl group having 1-30 carbon atoms; a saturated or unsaturated, substituted or unsubstituted cyclic alkyl group having 3-30 carbon atoms; or a substituted or unsubstituted aryl group having 6-30 carbon atoms.
2. The method as defined in claim 1 , wherein said dehydrating agent is selected from the group consisting of thionyl chloride, para-toluenesulfone chloride, phosphorous pentoxide, phosphorous oxytrichloride, a mixture of dimethylsulfoxide and oxalic acid chloride, trifluoroacetic anhydride, and a mixture of formaldehyde and formic acid.
3. The method as defined in claim 1 , wherein said amine base is selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, diisopropylamine, trimethylamine, triethylamine, diethylisopropylamine, and pyridine.
4. The method as defined in claim 1 , wherein said nucleophile is selected from the group consisting of Grignard reagent, organic lithium compound, organic zinc compound and organic aluminum compound.
5. The method as defined in claim 4 , wherein said Grignard reagent is methylmagnesium chloride, methylmagnesium bromide, methylmagnesium iodide, ethylmagnesium chloride, ethylmagnesium bromide, ethylmagnesium iodide, n-propylmagnesium chloride, n-propylmagnesium bromide, n-propylmagnesium iodide, iso-propylmagnesium chloride, iso-propylmagnesium bromide, iso-propylmagnesium iodide, cyclopentylmagnesium chloride, cyclohexylmagnesium chloride, cyclopentylmagnesium bromide, cyclohexylmagnesium bromide, cyclopentylmagnesium iodide, cyclohexylmagnesium iodide, propargylmagnesium bromide, vinylmagnesium chloride, vinylmagnesium bromide, phenylmagnesium chloride, phenylmagnesium bromide or phenylmagnesium iodide; said organic lithium compound is methyllithium, ethyllithium, propyllithium, iso-propyllithium, n-butyllithium, iso-butyllithium, neobutyllithium or phenyllithium; said organic zinc compound is dimethylzinc or diethylzinc; and said organic aluminum compound is trimethylaluminum or triethylaluminum.
6. The method as defined in claim 1 , wherein said organic solvent is selected from the group consisting of diethylether, di-n-butylether, methylneobutylether, isopropylether, tetrahydrofuran, 1,4-dioxane, n-hexane, n-heptane, benzene, toluene, xylene and mixtures thereof.
7. A method of preparing an optically pure (S)-tetrahydrofuranyl ketone, which comprises the following steps of:
dehydrating (S)-2-tetrahydrofuran amide, represented by the following chemical formula 1b, in the presence of a dehydrating agent and an amine base at 50 to 100° C. for 2 to 6 hours to obtain (S)-2-tetrahydrofuran nitrile represented by the following chemical formula 2b;
nucelophilic addition-reacting the (S)-2-tetrahydrofuran nitrile with a nucleophile in an organic solvent at the temperature range of −80 to 100° C. for 10 minutes to 4 hours, followed by hydrolyzing by use of aqueous acidic solution to produce (S)-tetrahydrofuranyl ketone represented by the following chemical formula 3b; and
recovering the resulting product obtained from the previous step:
wherein, R is a straight-chained or branched, saturated or unsaturated aliphatic alkyl group having 1-30 carbon atoms; saturated or unsaturated, substituted or unsubstituted cyclic alkyl group having 3-30 carbon atoms; or a substituted or unsubstituted aryl group having 6-30 carbon atoms.
8. The method as defined in claim 7 , wherein said dehydrating agent is selected from the group consisting of thionyl chloride, para-toluenesulfone chloride, phosphorous pentoxide, phosphorous oxytrichloride, a mixture of dimethylsulfoxide and oxalic acid chloride, trifluoroacetic anhydride, and a mixture of formaldehyde and formic acid.
9. The method as defined in claim 7 , wherein said amine base is selected from the group consisting of methylamine, ethylamine, propylamine, butylamine, dimethylamine, diethylamine, diisopropylamine, trimethylamine, triethylamine, diethylisopropylamine, and pyridine.
10. The method as defined in claim 7 , wherein said nucleophile is selected from the group consisting of Grignard reagent, organic lithium compound, organic zinc compound and organic aluminum compound.
11. The method as defined in claim 10 , wherein said Grignard reagent is methylmagnesium chloride, methylmagnesium bromide, methylmagnesium iodide, ethylmagnesium chloride, ethylmagnesium bromide, ethylmagnesium iodide, n-propylmagnesium chloride, n-propylmagnesium bromide, n-propylmagnesium iodide, iso-propylmagnesium chloride, iso-propylmagnesium bromide, iso-propylmagnesium iodide, cyclopentylmagnesium chloride, cyclohexylmagnesium chloride, cyclopentylmagnesium bromide, cyclohexylmagnesium bromide, cyclopentylmagnesium iodide, cyclohexylmagnesium iodide, propargylmagnesium bromide, vinylmagnesium chloride, vinylmagnesium bromide, phenylmagnesium chloride, phenylmagnesium bromide or phenylmagnesium iodide; said organic lithium compound is methyllithium, ethyllithium, propyllithium, iso-propyllithium, n-butyllithium, iso-butyllithium, neobutyllithium or phenyllithium; said organic zinc compound is dimethylzinc or diethylzinc; and said organic aluminum compound is trimethylaluminum or triethylaluminum.
12. The method as defined in claim 7 , wherein said organic solvent is selected from the group consisting of diethylether, di-n-butylether, methylneobutylether, isopropylether, tetrahydrofuran, 1,4-dioxane, n-hexane, n-heptane, benzene, toluene, xylene and mixtures thereof.