Faverviski Reaction and its mechanism .pptx

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1. Definition The Favorskii reaction is an organic chemistry reaction between an alkyne and a carbonyl group, under basic conditions. The reaction was discovered in the early 1900s by the Russian chemist Alexei Yevgrafovich Favorskii When the carbonyl is an aldehyde (R"=H), a rearrangement can occur to generate enone, although the secondary propargylic alcohol can be isolated in some cases.[2] When this rearrangement is catalyzed by an acid, it is called Meyer–Schuster rearrangement.

2. Mechanism Initially, the α'-carbon is deprotonated to generate an enolate ion which is followed by intra molecular nucleophilic substitution to give a cyclopropanone by ring closure. Thus formed cylcopropanone undergoes nucleophilic addition by a base at the carbonyl carbon which is followed by the cleavage of the CO-Cα bond. Usually the cleavage occurs so as to give less substituted and more stable carbanion.

3. Applications The Favorskii rearrangement is most useful for the preparation of branched-chain aliphatic carboxylic acids and their derivatives and for ring contraction of cyclic ketones. . In acyclic systems the reaction works best when the carbon atom bearing the halide is substituted.