Rhodium (â…¢) And Ruthenium (â…¡) Catalyzed C-H Activation And Its Mechanism Study

Reactions catalyzed by [Cp*RhCl2]2or [(p-cymene)RuCl2]2and its mechanism studies were focused on this thesis. They could contribute to our further insight into C-H bond activation reactions.The mechanism of the [(Cp*MCl2)2](M=Rh, Ir)-catalyzed oxidative annulation reaction of isoquinolones with alkynes was investigated in detail. In the first acetate-assisted C-H activation process (cyclometalated step) and the subsequent monoalkyne insertion into the M-C bonds of the cyclometalated compounds, both Rh and Ir complexes participated well. However, the desired final products, dibenzofa, g]quinolizin-8-one derivatives, were only formed in high yield when the Rh species participated in the final oxidative coupling of the C-N bond. Moreover, a Rh(I) sandwich intermediate was isolated during this transformation. The indium complexes were found to be inactive in the oxidative coupling process. All of the relevant intermediates were folly characterized and determined by single-crystal X-ray diffraction analysis. Based on this mechanistic study, a Rh(â…¢)â†'Rh(â… )â†'Rh(â…¢) catalytic cycle was proposed for this reaction.An efficient and regioselective ruthenium-catalyzed oxidative annulation of enamides with alkynes to synthesize N-acetyl substituted pyrroles via the cleavage of C(sp2)-H/N-H bonds is reported. Besides, the reactions can afford N-unsubstituted pyrroles by altering the reaction conditions slightly.The amidation reactions of8-methylquinolines with azides catalyzed by a cationic rhodium complex proceed efficiently to give quinolin-8-ylmethanamine derivatives in good yields via C(sp3)-H bond activation under external oxidant-free conditions. A catalytical competent five-membered rhodacycle has been isolated and characterized, revealing a key intermediate in the catalytic cycle. This is a rare example involving in Rhâ…¢ catalyzed C(sp3)-H bond activation.