The molecular photocatalyst fac-Re(2,2′-bipyridine)(CO)3Cl (Re-Cl) 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 Re-Cl as a catalyst for the visible-light-driven carboxylation of an alkene using CO2, with phenyl vinyl sulfone (1) serving as a model substrate. The catalytic system successfully catalyzed the carboxylation of 1 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.
Lorwongkamol et al. (Mon,) studied this question.