Synthesis of Allenes via Palladium-Catalyzed Hydrogen-Transfer Reactions: Propargylic Amines as an Allenyl Anion Equivalent
Hiroyuki Nakamura,* Takaya Kamakura, Makoto Ishikura and Jean-François Biellmann
*Department of Chemistry, Faculty of Science, Gakushuin University, Mejiro,
Toshima-ku, Tokyo 171-8588, Japan, Email: hiroyuki.nakamuragakushuin.ac.jp
H. Nakamura, T. Kamakura, M. Ishikura, J.-F. Biellmann, J. Am. Chem. Soc., 2004, 126, 5958-5959.
DOI: 10.1021/ja039175+
Abstract
Various propargylic amines underwent a palladium-catalyzed hydrogen-transfer reaction in the presence of (C6F5)3P, giving the corresponding allenes in good yields.
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Details
The document discusses the synthesis of allenes via palladium-catalyzed hydrogen-transfer reactions using propargylic amines as an allenyl anion equivalent. This method is significant due to the growing interest in allenes as building blocks for organic synthesis, particularly in transition metal-catalyzed reactions. Traditional methods for preparing allenes include displacement with organocopper species, homologation of 1-alkynes, and various reduction and coupling reactions. The study explores the transformation of propargylic amines into allenes using a palladium catalyst, with different amines yielding varying efficiencies. The best results were obtained with N,N-diisopropyl-3-phenylprop-2-ynylamine, achieving a 99% yield. The reactions were conducted in dioxane at 100°C for 24 hours. The study also examined the synthesis of various allenes from different aromatic iodides and propargylic amines, achieving yields up to 99%. The document includes detailed experimental procedures and results, highlighting the importance of (C6F5)3P in the catalytic process. The research presents a novel and efficient method for allene synthesis, with potential for further development and application in organic chemistry.
Key Words
Allenes, Propargylic Alcohols, Sonogashira Coupling
ID: J48-Y2004-1480