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DOI: 10.1055/s-0030-1257896
Palladium-Catalyzed Cross-Coupling by Intramolecular Activation of Trialkylsilanes
Contributor(s):Paul Knochel, Andreas J. WagnerKyoto University, Japan
Cross-Coupling Reactions through the Intramolecular Activation of Alkyl(triorgano)silanes
Angew. Chem. Int. Ed. 2010, 49: 4447-4450
Publication History
Publication Date:
23 August 2010 (online)
Key words
cross-coupling - trialkylsilanes - palladium
Significance
Herein, the authors report that 2-(2-hydroxyprop-2-yl)phenyl-substituted alkylsilanes selectively transfer an alkyl group to aryl and heteroaryl chlorides and bromides under palladium catalysis. Primary and secondary alkyl chains can be cross-coupled affording the alkylated products in very good yields.
Comment
While the ferrocene-based Qphos ligand gives optimal results for methylations, other alkyl groups, such as n-butyl or isopropyl, require the use of copper hexafluoroacetylacetonate. Without this salt O-arylation and Brook-type rearrangements predominantly take place, underlining the important role of alkylcopper species in the copper-to-palladium transmetalation step. For other examples of Si-Me bond activation, see: I. Ojima, D. A. Fracchiolla, R. J. Donovan, P. Banerji J. Org. Chem. 1994, 59, 7594.