Studies on formic acid-catalyzed dimerization of isorhapontigenin and of resveratrol to tetralins

The formic acid-catalyzed dimerization of stilbenes, isorhapontigenin and resveratrol, offers a route to tetralin derivatives. Seven products have been obtained, four of which were trisubstituted tetralins and three of which were formed from tetralins by losing substituted benzene groups and methoxy groups during the Diels–Alder reaction. The structures and configurational assignments of the compounds were elucidated mainly by spectroscopic analysis and a possible mechanism is proposed for the reaction. The anti-inflammatory activities of some derivatives obtained were also evaluated.