Alkynes as Synthetic Equivalents to Stabilized Wittig Reagents:  Intra- and Intermolecular Carbonyl Olefinations Catalyzed by Ag(I), BF3, and HBF4

Jong Uk Rhee and Michael J. Krische*
Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712
Org. Lett., 2005, 7 (12), pp 2493–2495
DOI: 10.1021/ol050838x
Publication Date (Web): May 11, 2005
Copyright © 2005 American Chemical Society

Abstract

Abstract Image

The first use of cationic silver (AgSbF4) as a catalyst for intra- and intermolecular alkyne−carbonyl coupling to form conjugated enones is described, and a comparison to corresponding Brønsted acid (HBF4) and Lewis acid (BF3) catalyst systems is made. Notably, intermolecular coupling proceeds stereoselectively to afford the corresponding trisubstituted enones as single geometrical isomers. This transformation represents a completely atom economical alternative to the use of stabilized Wittig reagents in carbonyl olefination and may be viewed as a formal alkyne−carbonyl metathesis.

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History

  • Published In Issue June 09, 2005
  • Received April 16, 2005

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