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

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Reaction Steps

A 300 ml three neck flask equipped with a magnetic stirrer and a three-way cock was charged with 200 ml of diethyl ether and 52 ml (154 mmol) of a diethyl ether solution of 3.0-Methylmagnesium bromide under nitrogen atmosphere. 3-tert-Butylcyclopentenone 17.8 g (129 mmol) was added dropwise in one hour on an ice and water bath. The solution was stirred at room temperature for 20 hours, and then the reaction solution was poured into 100 ml of 2N hydrochloric acid. The organic layer was separated, and the aqueous layer was extracted twice with 50 ml of ether. The organic layers thus obtained were combined and washed twice with a saturated sodium hydrogen carbonate aqueous solution, twice with water and twice with a saturated salt solution. The organic layer was dried on magnesium sulfate, and the solvent was removed by distillation. Then, the residue was purified by column chromatography to obtain 20.2 g (GC purity: 75%) of a pale yellow transparent liquid. The yield was 78%. The product was identified by means of a 1H-NMR spectrum. The measurement results thereof are shown below.

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