Palladium-Catalyzed Intermolecular α-Arylation of Zinc Amide Enolates under Mild Conditions

Takuo Hama, Darcy A. Culkin, and John F. Hartwig*
Contribution from the Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107
J. Am. Chem. Soc., 2006, 128 (15), pp 4976–4985
DOI: 10.1021/ja056076i
Publication Date (Web): March 25, 2006
Copyright © 2006 American Chemical Society
*

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

, john.hartwig@yale.edu

Abstract

Abstract Image

The intermolecular α-arylation and vinylation of amides by palladium-catalyzed coupling of aryl bromides and vinyl bromides with zinc enolates of amides is reported. Reactions of three different types of zinc enolates have been developed. The reactions of aryl halides occur in high yields with isolated Reformatsky reagents generated from α-bromo amides, with Reformatsky reagents generated in situ from α-bromo amides, and with zinc enolates generated by quenching lithium enolates of amides with zinc chloride. This use of zinc enolates, instead of alkali metal enolates, greatly expands the scope of amide arylation. The reactions occur at room temperature or 70 °C with bromoarenes containing cyano, nitro, ester, keto, fluoro, hydroxyl, or amino functionality and with bromopyridines. Moreover, the reaction has been developed with morpholine amides, the products of which are precursors to ketones and aldehydes. The arylation of zinc enolates of amides was conducted with catalysts bearing the hindered pentaphenylferrocenyl di-tert-butylphosphine (Q-phos) or the highly reactive, dimeric, Pd(I) complex {[P(t-Bu)3]PdBr}2.

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History

  • Published In Issue April 19, 2006
  • Received September 2, 2005

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