Assembling the prenylneoflavone system through a Pechmann condensation/Mitsunobu reaction/Claisen rearrangement/olefin cross-metathesis sequence

The multistep synthesis of a prenylneoflavone through a sequence of the Mitsunobu reaction/Claisen rearrangement/olefin cross-metathesis reaction has been accomplished in 5% yield over six steps starting from commercially available 3-methoxyacetophenone. The sequence is shown to be compatible with a Pechmann condensation which proved to be a robust and cost-effective method for the assembling of the α-pyrone core. The results open doors to a general approach to the prenylneoflavone system starting from phenol and acetophenone derivatives. Graphic abstract