Controlled Defluorinative Carboxylation Cascade of Sterically Hindered CF-Alkenes with Formate Salt via Photocatalysis.

A controlled cleavage of double C-F bonds in sterically hindered tetrasubstituted CF-alkenes using formate salt has been achieved through a photoinduced electron transfer approach. Diverse γ-branched multifunctionalized -difluoroalkenes and α-fluoroacrylic acids are obtained sequentially via hydrodefluorination and C-F bond carboxylation with good-to-high yields. Precisely controlling the quantity of formate salt and the reaction time is crucial for obtaining divergent defluorinative products.