Group 9 [Cp*MIII] complex-catalyzed C–H olefination of arenes in water at room temperature: a study on the catalytic activity

Herein, we report our discovery of group 9 [Cp*M-III] complexes catalyzing the olefination of arenes in water at ambient temperature. The reaction afforded the desired products in moderate to good yields. Among the group 9 [Cp*M-III] complexes, [Cp*RhCl2](2) was found to be the most efficient catalyst in this reaction, with the highest catalytic activity, the best scalability, the best recyclability and the broadest substrate scope. Mechanistic investigation revealed that the C-H bond cleavage was most likely to be achieved through the concerted metalation-deprotonation (CMD).