Stereoselective photochemistry of heteroaryl chalcones in solution and the antioxidant activities

Two new δ-truxinic type dimers; compound 1, rel-(1β,2α)-di-(2-thienoyl)-rel-(3β,4α)-di-(4-methoxy)phenylcyclobutane and compound 2, rel-(1β,2α)-di-(2-thienoyl)-rel-(3β,4α)-di-(3,4-dimethoxy)phenylcyclobutane were synthesized stereoselectively in solution by the dimerization of two known methoxy derivatives of heteroaryl chalcones (2E)-1-(2-thienyl)-3-(4-methoxy)-phenylpropen-1-one (3) and (2E)-1-(2-thienyl)-3-(3,4-dimethoxy)-phenylpropen-1-one (4). Precursor chalcones and the dimeric products showed antioxidant activities of different extents with respect to individual compounds as well as to the antioxidant methods.