one-pot green synthesis 1,3,5-triarylpentane-1,5-dione, triarylmethane, and flavonoid derivatives from the reaction between 2,4-dihydroxybenzaldehyde and hydroxyacetophenones via Aldol, Michael, and Friedel–Crafts additions using boric acid as catalyst in polyethylene glycol 400. The synthetic compounds demonstrated significant tyrosinaseinhibitory activities much stronger than that of kojicacid. More important