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. Formate serves as the C1 source, hydrogen donor, and reducing agent.