Ultrasound-assisted convenient synthesis of hypolipidemic active natural methoxylated (E)-arylalkenes and arylalkanones

An ultrasound-assisted convenient method was developed for the conversion of toxic methoxylated cis-isomer of arylalkenes into its hypolipidemic active trans-isomer. Treatment of cis-isomer or mixture of all three isomers () with ammonium formate and 10% Pd/C gave arylalkanes (), which upon oxidation with DDQ in anhydrous dioxane containing a little amount of silica gel, provided (E)-arylalkenes () in 42–72% yield depending upon the substituents attached at the aryl ring. The same method, upon addition of a few drops of water, provided hypolipidemic active arylalkanones () in 59–65% yield.