Hydrochloric Acid → 1-Chloro-4-(cyclopent-1-en-1-yl)benzene

Participants

Reaction Steps

From 575 g of p-chlorophenyl bromide and 78 g of magnesium turnings in 2.6 liters of anhydrous ether was prepared p-chlorophenyl magnesium bromide to which was added dropwise a solution of 252 g of cyclopentanone in 1 liter of ether. The mixture was stirred overnight and was decomposed by careful addition of dilute hydrochloric acid. The organic phase was separated, washed and dried, and the solvent was evaporated. The resulting solid was recrystallized from ethanol to give 316 g of 1-(p-chlorophenyl)cyclopentene, M.P. 71°-73° C., which was dissolved in 2.9 liters of acetic acid containing 6 ml of concentrated sulfuric acid. To this solution 133 g of 50% hydrogen peroxide was added dropwise during which time the reaction temperature was maintained at 30° to 35° C. The reaction mixture was stirred overnight after which water was added and the product was extracted into ether. The extract was washed, dried and the solvent evaporated leaving crude 2-(p-chlorophenyl)cyclopentanone which was distilled, B.P. 135°-154° C. (0.1 mm) yielding 140 g. The oxime, M.P. 154°-155° C. was reduced using Raney nickel in alcoholic ammonia to give 2-(p-chlorophenyl)cyclopentylamine which was subsequently converted to the hydrochloride salt, M.P. 226°-228° C. Following the procedure of Example 1, only substituting for cis-2-phenylcyclopentylamine hydrochloride, an appropriate amount of 2-(p-chlorophenyl)cyclopentylamine hydrochloride, the desired product was obtained, M.P. 253°-255° C.

Provenance & Evidence