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Title
Japanese: 
English:Functionalized Cyclopentadienyl Ligands and Their Substituent Effects on a Rhodium(III)‐Catalyzed Oxidative [4+2] Annulation of Indole‐ and Pyrrole‐1‐Carboxamides with Alkynes 
Author
Japanese: 山田 高之, 柴田 祐, 田中 健.  
English: Takayuki Yamada, Yu Shibata, Ken Tanaka.  
Language English 
Journal/Book name
Japanese:Asian Journal of Organic Chemistry 
English:Asian Journal of Organic Chemistry 
Volume, Number, Page Vol. 3    No. 0    pp. 1396?1402
Published date May 18, 2018 
Publisher
Japanese: 
English:Wiley-Blackwell 
Conference name
Japanese: 
English: 
Conference site
Japanese: 
English: 
Official URL https://doi.org/10.1002/ajoc.201800262
 
DOI https://doi.org/10.1002/ajoc.201800262
Abstract Abstract The effect of substituents on carbamoylmethyl?cyclopentadienyl (CpA) ligands on the neutral rhodium(III)?catalyzed oxidative [4+2] annulation of indole? and pyrrole?1?carboxamides with alkynes, in which the C?H bond cleavage is the partially rate?limiting step, was investigated. As a result, in the reactions with terminal alkynes, a rhodium(III) complex with a dimethyl?substituted CpA ligand (CpA3) showed high catalytic activity and improved the regioselectivity as compared to a commercially available Cp*RhIII complex. On the other hand, in reactions with internal alkynes, a rhodium(III) complex with a diphenyl?substituted CpA ligand (CpA1 or CpA2) showed high catalytic activity, which is comparable to the activity of the Cp*RhIII complex. Interestingly, a rhodium(III) complex with an electron?deficient di(ethoxycarbonyl)?substituted Cp ligand (CpE) that shows high catalytic activity toward the annulation of benzamides with internal alkynes, in which the C?H cleavage is rate?limiting, showed low catalytic activity toward the reactions with both terminal and internal alkynes. The ligand effects above provide important guidelines for the application of our CpA and CpE ligands to the rhodium(III)?catalyzed C?H bond functionalization reactions.

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