4-Chlorobenzaldehyde → 5-[(4-Chlorophenyl)methylidene]-2,2-dimethylcyclopentan-1-one

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Reaction Steps

100 ml of a 10% aqueous solution of sodium hydroxide were added to a mixture of 10 g of 2,2-dimethylcyclopentanone and 13.8 g of 4-chlorobenzaldehyde in 100 ml of ethanol at 0° C. After 30 minutes, a thick slurry was filtered off and the solid washed and then dried. 12.5 g of 2,2-dimethyl-5-(4-chlorobenzylidene)-1-cyclopentanone with a melting point of 120° C. were obtained. This compound, dissolved in 50 ml of THF, was added to a solution formed in the following manner: 1.9 g of sodium hydride (80% dispersion in mineral oil) in 50 ml of anhydrous DMSO were heated to 80° C. until complete dissolution of the solid. The solution was then diluted with 100 ml of THF, then cooled to -10° C. A solution of 11.5 g of trimethylsulphonium iodide in 80 ml of dimethyl sulphoxide were added to the mixture in the course of ten minutes and the mixture was stirred for 15 minutes at -10° C. A solution of 11.8 g of 2,2-dimethyl-4-chloro-5-(4-chlorobenzylidene)-1-cyclopentanone was then added in 100 ml of THF.

Provenance & Evidence