Acetic Acid → Methyl 6-methoxy-1-oxo-1,2,3,4-tetrahydronaphthalene-2-carboxylate

Beteiligte Stoffe

Reaktionsschritte

A suspension of 24.0 g (0.60 mole) of sodium hydride (60% dispersion in mineral oil) and 49.5 ml (52.9 g; 0.59 mole) of dimethyl carbonate (freshly distilled from sodium hydride) in 240 ml of tetrahydrofuran under a nitrogen atmosphere was stirred and heated to reflux. Reflux was maintained while a solution of 29.7 g (0.17 mole) of 6-methoxy-1-tetralone in 105 ml of tetrahydrofuran was added dropwise over two hours. After addition was complete, the mixture was stirred at reflux for an additional 90 minutes, cooled in ice, and treated dropwise with 36 ml of glacial acetic acid, followed by 450 ml of ice water. The two-phase reaction mixture was extracted with ethyl acetate (4×250 ml), and the combined organic layers were washed with water (1×600 ml), 5% aqueous sodium bicarbonate solution (3×600 ml), and water again. The ethyl acetate extract was dried (anhydrous sodium sulfate and evaporated (vacuum). The residue was pulverized and stirred in 500 ml of hexane. Filtration yielded 37.9 g (96% yield) of the ester product, mp 79°-81°, suitable for further synthesis. A sample purified by bulb-to-bulb distillation followed by recrystallization from hexane/ethyl acetate was analytically pure, mp 82°-84° (a mp of 88°-89° is given by J. Jacques and A. Horeau, Bull. Soc. Chem. France, 512 (1950)).

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