Ethylene Glycol → 3-Bromo-4,4-ethylenedioxy-bicyclo[3.2.1]oct-6-en-2-one

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Reaction Steps

A sodium glycolate solution is prepared by stirring 124 mg (5.4 mmol) of metallic sodium into 2.7 ml (42.42 mmol) of anhydrous ethylene glycol at ambient temperature and, when the sodium has completely dissolved, 1.5 ml of tetrahydrofuran are added. To the resulting monosodium glycolate solution there is then added dropwise a solution of 1 g (3.6 mmol) of 3,4-dibromo-bicyclo[3.2.1]octa-3,6-dien-2-one (prepared according to Organic Lett. 4(12), 1997 (2002)) dissolved in 5 ml of tetrahydrofuran. The reaction mixture is then stirred at ambient temperature for 90 minutes with TLC monitoring (mobile phase hexane/ethyl acetate 4:1). The reaction mixture is then treated with 8 ml of 10% sodium dihydrogen phosphate solution and extracted with ethyl acetate (3×). The organic phase is washed with water to remove ethylene glycol, then dried and concentrated by evaporation. 930 mg (˜100%) of 3-bromo-4,4-ethylenedioxy-bicyclo[3.2.1]oct-6-en-2-one are obtained in the form of a white solid.

Provenance & Evidence