<i>fac</i>-Re(2,2′-bipyridine)(CO)₃Cl Catalyzes Visible-Light-Driven Functionalization of an Organic Substrate with CO₂

The molecular photocatalyst <i>fac</i>-Re-(2,2'-bipyridine)-(CO)₃Cl (<b>[Re-Cl]</b>) is well established and has been extensively investigated for the highly active and selective conversion of CO₂ to CO. However, its reactivity in processes other than CO₂ reduction has rarely been explored. Herein, we report the application of <b>[Re-Cl]</b> as a catalyst for the visible-light-driven carboxylation of an alkene using CO₂, with phenyl vinyl sulfone (<b>1</b>) serving as a model substrate. The catalytic system successfully catalyzed the carboxylation of <b>1</b> to its corresponding carboxylic acid, with complete suppression of CO formation throughout the reaction. A turnover number (TON) of up to 2600, along with excellent regioselectivity, was achieved under optimized conditions. Control experiments revealed the key role of each reaction component, while isotope labeling with ¹³CO₂ confirmed that the carboxyl group originated from CO₂. Furthermore, mechanistic investigations suggested that the Re-CO₂ intermediate reacts directly with the alkene. These findings highlight the potential of Re-based molecular complexes for broader reactivities and expand their applicability in sustainable synthetic transformations.