Trichloroacetyl chloride → 3-(Benzyloxymethyl)-2,2-dichlorocyclobutanone

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Zinc dust (6.54 g, 0.1 mol) was suspended in water (30 ml) and argon bubbled through the suspension for 15 minutes before the addition of copper (II) sulphate (780 mg, 3.1 mmol). The reaction mixture was stirred at room temperature, under argon for 30 minutes. The mixture was filtered under a stream of argon and the solid washed with water (100 ml), acetone (100 ml) and dried in vacuo for 4 hours. The resultant zinc/copper couple was suspended in diethyl ether:1,2-dimethoxyethane (70 ml:10 ml) under argon and allyl benzyl ether (4.6 ml, 30 mmol) added. A solution of trichloroacetyl chloride (9 ml, 81 mmol) in diethyl ether:1,2-dimethoxyethane (58 ml:7 ml) was added dropwise over 45 minutes and the reaction mixture heated to reflux for 48 hours. The reaction mixture was filtered through Celite® and the salts washed with diethyl ether (3×70 ml). The filtrate was evaporated in vacuo and the residue redissolved in hexane (150 ml). The remaining solids were removed by filtration and the filtrate washed with a saturated aqueous solution of sodium hydrogen carbonate (2×100 ml), brine (80 ml), dried over magnesium sulphate, filtered and evaporated in vacuo. The crude material was purified by column chromatography over silica gel eluting with 10-25% hexane:diethyl ether. The title compound was obtained as a yellow oil (7.03 g, 27.3 mmol, 91%).

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