Electro-organic Synthesis Of Some Natural Products Analogues

In this project an attempt was made to prepare lignansrnby oxidative and reductive coupling of the a-enolates andrna-bromo derivatives of substituted propiophenones respectively.rnPropiophenone derivatives were prepared by the addition ofrnethylmagnesium iodide to substituted benzaldehydes followedrnby oxidation of the intermediate alcohols with Jones’ reagent.rnThe a-bromo propiophenone derivatives were prepared byrntreating the ketones obtained with bromine in chloroformrnsolution.rnPrior to preparative electrolysis of the a-enolatesrnand a-bromo derivatives, the working potentials were determinedrnby cyclic voltammetry and PC polarography. It wasrnfound out that the carbonyl functional group was reducedrnat a potential greater than -1.9V and C-Br bond it wasrncleaned to the corresponding free radical or carbanionrnin the potential range of -0,2V to -1.4V.rnPreparative electrolysis of 3,4-methylenedioxypropiophenonernin methanol containing, sodium methoxide and pota -rnssium iodide at 1.05V (divided cell)gave the a-hydroxyrnprcpiophenone derivatives. The methyl, ether propiophenonernderivatives were also obtained when the ketonesrnwere electrolyzed at various working potentials in qqueousmethanolrnmedium containing the electrolytes sodium hydroxidernand potassium iodide. Exhaustive preparative electrolysisrnof the a-bromo-3,4-dimethoxynropiophenone derivativernat -1.7V vs SCE using platinum electrode(divided cell)gaverna lipnan of the 1,4-diaroylbutane derivatives.

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