1,4-Biradicals generated upon photo-irradiation of 2-aryl-3-{(thiophen-2-yl)methoxy}chromones produced angular tetracyclic products bearing the thienyl group. The dehydrogenation and ring contraction products were also observed depending upon the electron density on the 2-aryl ring.
alkoxychromone; type-II reaction; 1,4-biradical; ring contraction; angular tetracyclic
