Double-tandem [4π+2π]·[2π+2π]·[4π+2π]·[2π+2π] synthetic sequence with photoprotolytic oxametathesis and photoepoxidation in the chromone series.

Chromones are introduced into a double-tandem [4(π)+2(π)]·[2(π)+2(π)]·[4(π)+2(π)]·[2(π)+2(π)] synthetic sequence, culminating in photoprotolytic oxametathesis, which leads to an expeditious growth of molecular complexity over a few experimentally simple steps. The overall reaction can potentially be utilized in diversity-oriented synthesis, as it allows for three or more diversity inputs furnishing novel unique polycyclic scaffolds decorated with a variety of functionalities and aromatic/heterocyclic pendants. The polycyclic alkenes, resulting from the oxametathesis step, were found to undergo efficient and clean photoinduced epoxidation when irradiated in the presence of molecular oxygen.