THE CONDENSATION OF CERTAIN γ-KETONIC ESTERS WITH AROMATIC ALDEHYDES

Abstract

The condensation of methyl and ethyl α-phenyl-β-(para-substituted)benzoyl propionates with benzaldehyde and piperonal in the presence of sodium methylate, followed by acidification, has been found to produce cyclic compounds; the latter are shown to be lactols, six of which are described. The spontaneous ring closure is probably due to the highly branched chain. A mechanism for the reaction is proposed.On oxidation with chromic acid, α-diketones are formed; the latter contain the aryl group introduced as aldehyde. The lactols resemble triphenylcarbinol in several respects, forming a chloride, methyl ether, and acetate on appropriate treatment, all of which, on hydrolysis, regenerate the lactol. They also give colored solutions with concentrated sulphuric acid, from which the starting material is recovered on addition to water. From this work it is evident that in arylated γ-ketonic esters the hydrogen atom alpha to the ketone carbonyl group is more active in alkaline aldol condensations than the hydrogen in the alpha position to the carbalkoxy carbonyl group; the observation of others, that the conjugated system [Formula: see text] is more stable than [Formula: see text], has been confirmed.