反应详情

Into a solution of 6.18 g (42.9 mmol) of tetrahydropyran-4-carboxylic acid methyl ester in tetrahydrofuran (140 mL) was dropped, at −78° C. under an atmosphere of argon, 25.7 mL (51.5 mmol) of 2 mol/L lithium diisopropylamide in hexane-heptane-ethylbenzene (available from Aldrich), and stirred for 90 minutes. To this solution, 8.5 g (60.1 mmol) of methyl iodide was added at −78° C. and stirred for 4 hours. Saturated aqueous ammonium chloride solution (30 mL) was added to the reaction mixture and stirred for 10 minutes. Then the reaction mixture was concentrated to about one third of its volume under a reduced pressure and the residue was extracted with ethyl acetate-hexane (3:1). The organic layer was washed with water (twice) and saturated brine successively, and dried over anhydrous magnesium sulfate, and then the solvent was removed. The obtained residue was purified by medium pressure liquid column chromatography on silica gel (developing solvent: hexane:ethyl acetate) to obtain 5.9 g (yield 86.4%) of 4-methyltetrahydropyran-4-carboxylic acid methyl ester (IX-60) as colorless liquid. Its physical property is shown below.

1. stirringstirred for 10 minutes
2. concentrationThen the reaction mixture was concentrated to about one third of its volume under a reduced pressure
3. extractionthe residue was extracted with ethyl acetate-hexane (3:1)
4. washThe organic layer was washed with water (twice) and saturated brine successively
5. dry with materialdried over anhydrous magnesium sulfate
6. customthe solvent was removed
7. customThe obtained residue was purified by medium pressure liquid column chromatography on silica gel (developing solvent: hexane:ethyl acetate)