Electro-organic Synthesis of Some Natural Products Analogues
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Date
1980-07
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Addis Ababa Universty
Abstract
In this project an attempt was made to prepare lignans
by oxidative and reductive coupling of the a-enolates and
a-bromo derivatives of substituted propiophenones respectively.
Propiophenone derivatives were prepared by the addition of
ethylmagnesium iodide to substituted benzaldehydes followed
by oxidation of the intermediate alcohols with Jones’ reagent.
The a-bromo propiophenone derivatives were prepared by
treating the ketones obtained with bromine in chloroform
solution.
Prior to preparative electrolysis of the a-enolates
and a-bromo derivatives, the working potentials were determined
by cyclic voltammetry and PC polarography. It was
found out that the carbonyl functional group was reduced
at a potential greater than -1.9V and C-Br bond it was
cleaned to the corresponding free radical or carbanion
in the potential range of -0,2V to -1.4V.
Preparative electrolysis of 3,4-methylenedioxypropiophenone
in methanol containing, sodium methoxide and pota -
ssium iodide at 1.05V (divided cell)gave the a-hydroxy
prcpiophenone derivatives. The methyl, ether propiophenone
derivatives were also obtained when the ketones
were electrolyzed at various working potentials in qqueousmethanol
medium containing the electrolytes sodium hydroxide
and potassium iodide. Exhaustive preparative electrolysis
of the a-bromo-3,4-dimethoxynropiophenone derivative
at -1.7V vs SCE using platinum electrode(divided cell)gave
a lipnan of the 1,4-diaroylbutane derivatives.
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Electro-organic