A Biomimetic Approach to the Rocaglamides Employing Photogeneration of Oxidopyryliums Derived from 3-Hydroxyflavones

A unified biomimetic approach to the aglain−forbaglin−rocaglamide classes of natural products is reported. The approach involves photogeneration of oxidopyryliums via excited-state intramolecular proton transfer (ESIPT) of 3-hydroxyflavones followed by [3+2] dipolar cycloaddition to the aglain core. An α-ketol (acyloin) rearrangement was employed to transform the aglain core to the rocaglamide framework. This approach was successfully used for the synthesis of the natural product (±)-methyl rocaglate.