2-Ketobutyric acid methyl ester → Methyl 2-[3-(1,3-dioxolan-2-yl)-2-fluoro-4-pyridinyl]-2-hydroxybutanoate

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Reaction Steps

6.9 ml (11 mmol) of 1.6M butyllithium in hexane are added dropwise to a solution, stirred at −78° C. under an argon atmosphere, of 3.1 g (11 mmol) of 3-(1,3-dioxolan-2-yl)-2-fluoro-4-iodopyridine in 100 ml of THF. The reaction mixture is then stirred for 10 minutes at −78° C. before the dropwise addition of a solution of 1.5 g (13 mmol) of methyl 2-oxo-butyrate in 20 ml of THF. The mixture is stirred for 3 hours at −78° C., hydrolysed with a mixture of water/THF, and decanted. The aqueous phase is extracted 3 times with 50 ml of ethyl acetate each time, and the combined organic phases are dried over magnesium sulphate and then concentrated. The expected product is obtained by purification of the residue by chromatography over silica (eluant: dichloromethane/acetone 95/5).

Provenance & Evidence