Kumada-Corriu Reactions of Alkyl Halides with Alkynyl Nucleophiles
Lian-Ming Yang, Li-Fu Huang and Tien-Yau Luh*
*Institute of Chemistry, Academia Sinica, Nangang, Taipei, Taiwan 115,
Email: tyluh
chem.sinica.edu.tw
L.-M. Yang, L.-F. Huang, T.-Y. Luh, Org. Lett., 2004, 6, 1461-1463.
DOI: 10.1021/ol049686g
Abstract
Pd2(dba)3-Ph3P-catalyzed Kumada-Corriu coupling reactions of unactivated alkyl bromides or iodides with alkynyllithiums or the corresponding Grignard reagents furnish Csp-Csp3 bond formation. The superior performance of Ph3P ligand over the trialkylphosphine ligands indicates that this cross-coupling reaction may be a reductive-elimination-controlled process.
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Details
The document discusses the Kumada−Corriu coupling reactions of unactivated alkyl bromides or iodides with alkynyl nucleophiles, catalyzed by Pd(dba)−PhP. This reaction forms Csp−Csp3 bonds and uses alkynyllithiums or Grignard reagents as nucleophiles. The study highlights the superior performance of the Ph3P ligand over trialkylphosphine ligands, suggesting that the reaction is controlled by the reductive elimination step. The mechanism involves oxidative addition, transmetalation, and reductive elimination. The research found that zero-valent palladium catalysts are essential, and Ph3P is more effective than trialkylphosphine ligands in preventing oxidative dimerization of alkynes. The study also demonstrated that slow addition of the Grignard reagent improves yields. Various alkyl halides and alkynyl nucleophiles were tested, showing satisfactory yields. The findings suggest that Pd2(dba)3 and Ph3P are crucial for the catalytic process, and the study provides insights into the development of new catalytic systems. The research was supported by the National Science Council and the Ministry of Education of the Republic of China. Experimental details and NMR spectra are available online.
Key Words
Palladium-Catalysis, Kumada Coupling, Alkynes
ID: J54-Y2004-330
