1-Phenyl-1-propanone → HCID 178444327, compound

Participants

Reaction Steps

A solution of 7.1 mmol of ethylmagnesium bromide (prepared from 172 mg of magnesium and 530 μl of ethyl bromide) in 20 ml of absolute tetrahydrofuran was placed at -78° C. while gassing with argon in a sulphonation flask provided with a thermometer, dropping funnel and serum cap and treated in sequence with 3.6 ml of a 0.48M solution of dilithium tetrachlorocuprate in absolute tetrahydrofuran and with a solution of 500 mg of p-[trans-4-(3-acetoxy-trans-1-propenyl)cyclohexyl]benzonitrile in 10 ml of absolute tetrahydrofuran. After completion of the addition, the mixture was warmed to -15° C., stirred at this temperature for 1.5 hours, subsequently treated with 20 ml of saturated ammonium chloride solution and stirred at room temperature for a further 1 hour. The aqueous phase, which was now deep blue, was separated and extracted twice with 50 ml of diethyl ether each time. The organic phases were washed twice with 50 ml of water each time, dried over magnesium sulphate and concentrated. Low-pressure chromatography (0.5 bar) of the residue (0.4 g) on silica gel with ethyl acetate/petroleum ether (vol. 3:97) gave 375 mg of crude p-[trans-4-(trans-1-pentenyl)cyclohexyl]benzonitrile which, according to analysis by gas chromatography, was contaminated to 8.5% with p-[trans-4-(trans-1-pentenyl)cyclohexyl]propiophenone and to 4.0% with p-[trans-4-(1-vinylpropyl)cyclohexyl]benzonitrile. Treatment of this crude product with an excess of sodium borohydride in methanol at 0° C. (in order to reduce the propiophenone), working-up, low-pressure chromatography (0.5 bar) on silica gel with ethyl acetate/petroleum ether (vol. 1:9) and finally recrystallization from methanol at -78° C. gave p-[trans-4-(trans-1-pentenyl)cyclohexyl]benzonitrile in a purity of 98.6%; m.p. (C--N) 15.5° C., cl.p. (N--I) 57.0° C.

Provenance & Evidence