1-Bromo-2-methylpropane → 2-Isobutyl-3-ketoglutarate diethyl ester

関与物質

反応手順

Diethyl 3-oxopentanedioate (45.5 ml, 0.25 mol) was added to a suspension of magnesium ethoxide (prepared from magnesium turnings (9 g, 0.375 mol) and iodine (0.1 g) in dry ethanol (275 ml)), and the mixture was heated under reflux for 90 min. 1-Bromo-2-methylpropane (54 ml, 0.5 mol) was added, and the reaction was heated under reflux for 16 h. Further 1-bromo-2-methylpropane (27 ml, 0.25 mol) was added to the boiling mixture, and after 3 h the solvent was evaporated in vacuo. The residue was partitioned between 2 N hydrochloric acid and ether. After extracting the aqueous phase with ether, the combined organics were washed successively with water, 5% sodium bicarbonate, water and brine, then were dried (Na2SO4) and evaporated in vacuo. The residue was distilled to give the title compound as a colourless oil (40 g, 62%), bp 118°-120° C. (1 mmHg). δ (CDCl3): 0.9 (6H, d, J=6Hz), 1.25 (6H, t, J=7Hz), 1.4-1.9 (3H, m), 3.5 (2H, s), 3.7 (1H, d, J=9Hz) and 4.2 (4H, q, J=7Hz).

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