Zinc Chloride Catalyzed Collective Synthesis of Arylmethylene Bis(3- hydroxy-2-cyclohexene-1-ones) and 1,8-Dioxo-octahydroxanthene/acridine Derivatives

Catalytic amount of ZnCl2 efficiently promoted rapid synthesis of arylmethylene bis(3-hydroxy-2-cyclohexene- 1-one) in water at room temperature in excellent yield. At elevated temperature, ZnCl2 also catalyzed one-pot synthesis of 1,8-dioxo-octahydroxanthene and 1,8-dioxo-decahydroacridine derivatives in good yield. In specific instances, unusual dissociation of dimedone from the arylmethylene bis(3-hydroxy-2-cyclohexene-1-one) was identified in the reaction medium. It was minimized/avoided by the addition of known excess dimedone to the reaction mixture in the one-pot synthesis of 1,8-dioxo-octahydroxanthene