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(pi)+2(pi)]center dot[2(pi)+2(pi)]center dot[4(pi)+2(pi)]center dot[2(pi)+2(pi)] 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.