The condensation of some phenols with malic acid, maleic acid and maleic anhydride

Abstract

Optimum yields of coumarins are obtained by Pechmann condensation of polyphenols with malic acid in the presence of sulphuric acid at 100- 120° in the absence of water. Under these conditions the Ponndorf reaction with maleic acid does not occur.    Pechmann condensation of pyrogallol with malic acid gives substantial quantities of the novel dicoumarin (2), while the condensation of resorcinol with maleic anhydride in the presence of zinc chloride yields the benzoyl dihydrocoumarin (5a).