Hydrochloric Acid → 3-tert-Butyl-1-ethylcyclopenta-1,3-diene

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Reaction Steps

A 300-ml three-necked flask equipped with a magnetic stirring bar and a three-way cock was charged with 200 ml of dehydrated diethyl ether and 52 ml (154 mmol) of a 3.0-M diethyl ether solution of ethyl magnesium bromide under a nitrogen atmosphere. To the solution was added dropwise 17.8 g (129 mmol) of 3-tert-butylcyclopentenone over 1 hour in an ice bath. After stirring at room temperature for 20 hours, the reaction solution was poured into 100 ml of 2N hydrochloric acid. The organic layer was separated and the aqueous layer was subjected to extraction with 50 ml of ether twice. The combined organic layer was washed with saturated sodium hydrogen carbonate aqueous solution twice, with water twice, and with saturated brine twice. After drying over magnesium sulfate, the solvent was distilled off. The residue was purified by column chromatography to obtain 20.2 g (GC purity: 75%) of pale yellow transparent liquid. The yield was 78%. The identification was carried out by 1H-NMR spectrum. The measurement results are shown below.

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