Diisopropylamine → 3-[(Z)-6-methoxycarbonyl-2-hexenyl]-4-oxotetrahydropyran

Participants

Reaction Steps

To a solution of lithium diisopropylamide (2.40 mmol) in tetrahydrofuran (5 ml), prepared from diisopropylamine (0.35 ml) with n-butyllithium (1.7 ml, 1.5 M solution in hexane) using an usual manner, was added 4-oxotetrahydropyran (220 mg) in tetrahydrofuran (2 ml) at -78° C. and the mixture was stirred for 30 minutes at the same temperature. To the resulting solution was added methyl(Z)-7-bromo-5-heptenate (500 mg) in tetrahydrofuran (2 ml) at -78° C. After being stirred at room temperature for 5 hours, the reaction mixture was quenched with saturated aqueous ammonium chloride and the solution was extracted with ethyl acetate. The organic layer was washed successively with water and brine and dried over magnesium sulfate. The solvent was evaporated in vacuo and the residue was chromatographed on a silica gel column (10 g) with a mixture of n-hexane and ethyl acetate (4:1) as an eluent to give 3-[(Z)-6-methoxycarbonyl-2-hexenyl]-4-oxo-tetrahydropyran (100 mg) as a colorless oil.

Provenance & Evidence