Tuning the Regioselective Functionalization of Trifluoromethylated Dienes via Lanthanum-Mediated Single C-F Bond Activation

The development of new fluorine-containing building blocks and their efficient synthetic access is currently a challenging research field. Herein, the highly regio- and stereoselective addition of a large range of aldehydes onto trifluoromethylated benzofulvenes was achieved using a simple La/I-2/DIBAL-Cl system via a selective C-F bond activation process. This versatile methodology provided homodienyl alcohols bearing a terminal CF2-alkene with potential further applications, as shown by the dehydration to the first benzofulvenes carrying a difluorovinyl group. In addition, for certain electron-poor aldehydes, unprecedented ipso substitution of the CF3 group in a diene was observed, which, according to DFT studies, is related to the presence of the large, Lewis-acidic lanthanum metal.

Automated summary

A highly selective method was developed in this study for the regio- and stereoselective addition of a variety of aldehydes onto trifluoromethylated benzofulvenes. The resulting products have potential for further applications and can be transformed into benzofulvenes carrying a difluorovinyl group.