HFO-1234yf as a CF3-building block: Synthesis of trifluoromethyl-benzophenone derivatives by deoxygenative aromatisation

Trifluoromethyl ynones derived from the 4th generation refrigerant 2,3,3,3-tetrafluoropropene (HFO-1234yf) undergo rapid Diels-Alder cycloaddition reactions with furans in near quantitative yields. Subsequent deoxygenation of the resulting oxabicyclic adducts leads to formation of ortho-trifluoromethylbenzophenones in generally good yields without the need for purification by column chromatography. Complete selectivity for a single regioisomer was observed in all cases. This method provides a new route from an inexpensive feedstock to highly substituted CF3-aromatic systems that can be difficult to access selectively by established methods.