Reactions of Carboxylic Acids with Vinyl Grignard Reagent

Abstract

The reactions of vinyl Grignard reagent with carboxylic acids have been studied in detail in various solvents.
The order for the ease of formation of ketone [1] is (CH), CCOOH, HOOH> C, H, COOH> (CH, ) 2CHCOOH> CH₃ (CH₂), COOH> CH, (CH₂) 2COOH > CH, COOH. Pivalic and cyclohexanecarboxylic acids having bulky alkyl groups yield ketone [1]quantitatively.
This result may be explained in terms of the steric hindrance of alkyl groups. It was found that the formation of ketone [1] becomes further difficult with increasing solvent basicity. The reactivity of vinyl Grignard reagent with a, 0-unsaturated carbonyl compouds was found to be similar to that with carboxylic acids. From the result obtained, it was found that the reaction of vinyl Grignard reagent with carboxylic acid proceeds via corresponding alkyl vinyl ketone intermediate.