Acetophenone → Ethyl 3-(4-cyclohexylphenyl)-3-oxopropanoate

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Reaction Conditions

Reaction Steps

Into a three-neck 2 L round-bottom flask equipped with an addition funnel, nitrogen inlet, magnetic stirrer, heating mantle, thermocouple and condenser, was placed 21.7 g (0.543 moles) of a 60%-in-oil dispersion of sodium hydride. To this was added dry hexane (1 L). The resulting suspension was stirred for 15 minutes, stirring was halted and the solids were allowed to settle. The clear supernatant containing the hexane and dissolved oil was then removed via a cannula. Diethyl carbonate(1 L) was added and the suspension was heated to 120° C. To this suspension was cautiously added dropwise, over 40 minutes, a solution of 100 g (0.494 moles) of 4′-cyclohexyl actephenone dissolved in 250 mL of diethyl carbonate. As addition proceeded a reaction initiated, hydrogen was evolved and the color changed to tan. After the acetophenone derivative addition was complete, the reaction was heated for 1 additional hour. The reaction mixture was cooled and was poured into a 2 L separatory funnel. The diethyl carbonate layer was twice washed with 10% acetic acid solution and then dried over MgSO4. The solution was then filtered and concentrated on a rotary evaporator followed by pumping with high vacuum at 70° C. for 18 hr. The concentrated solution crystallised on cooling over 24 hrs to give a colorless solid. The product obtained was then used without further purification, yield 133 g (98%). 1H NMR reveals that the β-keto ester product actually exists as a keto-enol tautomer mixture in solution, with the keto form predominant in the solid.

Provenance & Evidence