Synthesis and photochemical <i style="">H</i>-abstractions of some 2-thienyl/furyl-3-allyloxybischromones

216-223The photoirradiation of bischromones with trans-2-butenyl and 2-butynyl, has produced tetracyclic compounds and isomerized ethers as photoproducts. The formation of these photoproducts has been rationalized through H-abstraction by C=O group of the pyrone moiety. The chemical efficiency of the bischromone phototransformations is dictated by the nature of the intermediate spacer unit