Ethyl 2-oxovalerate → 4-HYDROXY-4-METHYL-5-HEXENOIC ACID gamma LACTONE

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Reaction Steps

To a solution of ethyl 2-ketopentanoate (10 mL, 71 mmol) in 100 mL of THF at −78° C. was added dropwise a solution of 1.0 M vinyl magnesium bromide (80 mL, 80 mmol). After completion of the addition, the mixture was stirred for two more hours, the cooling bath was removed and the mixture was gradually warmed to ambient temperature. After the removal of the most of the solvent, the residue was poured to 2N HCl aqueous solution, extracted with ethyl acetate and dried over MgSO4. Purification by lash column chromatography on silica gel with DCM as elute afforded 4.80 grams of 5-methyl-5-vinyl-dihydro-furan-2-one. 1H-NMR (300 MHz, CDCl3) δ (ppm): 5.824-5.917 (dd, 1H); 5.29 (d, 1H); 5.13 (d, 1H); 2.50-2.56 m, (2H); 2.07-2.18 (m, 2H); 1.48 (s, 3H).

Provenance & Evidence