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

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Reaction Steps

To a 500 ml three-neck flask equipped with a magnetic stirrer chip and a three-way cock, 100 ml of dehydrated diethyl ether and 57 ml (170 mmol) of diethyl ether solution of 3.0 M methyl magnesium bromide were charged under a nitrogen atmosphere. In the ice bath, 19.6 g (142 mmol) of 3-tert-butylcyclopentenone was added dropwise over 1 hour. The resultant 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 obtained organic layers were combined, washed twice with a saturated aqueous solution of sodium hydrogencarbonate, twice with water, and twice with saturated brine and dried over magnesium sulfate and the solvent was distilled. Thereafter, the purification was conducted by distillation under reduced pressure to obtain 13.5 g of a pale yellowy transparent liquid. The yield was 70%. Identification was done by 1H-NMR spectrum. The measurement results are shown as follows.

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