Premium
Investigation and Comparison of the Mechanistic Steps in the [(Cp*MCl 2 ) 2 ] (Cp*=C 5 Me 5 ; M=Rh, Ir)‐Catalyzed Oxidative Annulation of Isoquinolones with Alkynes
Author(s) -
Wang Nuancheng,
Li Bin,
Song Haibin,
Xu Shansheng,
Wang Baiquan
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201203374
Subject(s) - annulation , iridium , catalysis , chemistry , oxidative coupling of methane , oxidative addition , yield (engineering) , oxidative phosphorylation , alkyne , catalytic cycle , rhodium , medicinal chemistry , single crystal , crystal structure , stereochemistry , photochemistry , crystallography , organic chemistry , materials science , biochemistry , metallurgy
The mechanism of the [(Cp*MCl 2 ) 2 ] (M=Rh, Ir)‐catalyzed oxidative annulation reaction of isoquinolones with alkynes was investigated in detail. In the first acetate‐assisted CH‐activation process (cyclometalated step) and the subsequent mono‐alkyne insertion into the MC bonds of the cyclometalated compounds, both Rh and Ir complexes participated well. However, the desired final products, dibenzo[ a,g ]quinolizin‐8‐one derivatives, were only formed in high yield when the Rh species participated in the final oxidative coupling of the CN bond. Moreover, a Rh I sandwich intermediate was isolated during this transformation. The iridium complexes were found to be inactive in the oxidative coupling processes. All of the relevant intermediates were fully characterized and determined by single‐crystal X‐ray diffraction analysis. Based on this mechanistic study, a Rh III →Rh I →Rh III catalytic cycle was proposed for this reaction.