WITTIG-HORNER REACTIONS AND TRANSESTERIFICATION BY ANIONIC ACTIVATION OF C-H AND O-H BONDS IN A HETEROGENEOUS POTASSIUM CARBONATE-ALCOHOL SOLUTION

The Wittig-Horner reaction carried out in various alcohols is accompanied by transesterification of the alkyl radical of the alpha, beta-ethylenic ester formed. The occurrence of these two reactions in the same reaction medium is affected by the behavior of: i) the alcohol (solvent and reagent), ii) potassium carbonate (reagent and catalyst). The propensity for the two reactions to occur was found to depend on the polarity of the alcohol. Protic alcohols speeded both the Wittig-Horner and the subsequent transesterification reaction. Both reactions were quantitative despite the use of non-stoichiometric amounts of potassium carbonate. Regeneration in situ of the solid base observed in aprotic medium was markedly enhanced under these reaction conditions. The mechanism proposed for these two reactions incorporates this regeneration process.