Preparation of (z)-olefins from the reaction of ethyl 3,3-dimethyl acryl ate (1) and carbonyl compounds was investigated. Ethyl 3,3-dimethylacrylate (1) was deprotonated by LDA in THF, and then this anion was allowed to react with benzaldehyde to give (2Z,4E)-3-methyl-5-phenyl-2,4-pentadienoic acid (2a) in 97 yield. Although the anion of 1 has several nucleophilic centers, product 2a was obtained selectively. Other aromatic and aliphatic aldehydes were converted to 5-substituted (2Z,4E)-3-methyl-2,4-pentadienoic acids in more than 74 yields.
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