A Trialkylphosphine-Derived Palladacycle as a Catalyst in the Selective Cross-Dimerization of Terminal Arylacetylenes with Terminal Propargyl Alcohols and Amides

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• 作者：Matthew G. Lauer ; Benjamin R. Headford ; Olivia M. Gobble ; Michelle B. Weyhaupt ; Deidra L. Gerlach ; Matthias Zeller ; Kevin H. Shaughnessy
• 刊名：ACS Catalysis
• 出版年：2016
• 出版时间：September 2, 2016
• 年：2016
• 卷：6
• 期：9
• 页码：5834-5842
• 全文大小：546K
• 年卷期：0
• ISSN：2155-5435

文摘

A method for the selective cross-dimerization of terminal aryl alkynes with propargyl alcohols to afford linear (E)-enynol products is reported. The complex [Pd(μ-κ²-O,O-OAc)(κ²-C,P-(t-Bu)₂PCH₂C(Me)₂CH₂)]₂ selectively affords (E)-5-aryl-2-en-4-yn-1-ol products in good yields under mild conditions with high chemo-, regio-, and stereoselectivity. In contrast, previously reported examples of this reaction afford the branched 4-aryl-2-hydroxymethanol-1-buten-3-yne. Propargyl amides are also selectively cross-dimerized, but with lower regioselectivity for the linear enyne. The method has been applied to the synthesis of (E)-5-phenyl-2-penten-4-yn-1ol, which is a precursor to type 2 diabetes drug candidate NNC 61-4655, in 72% yield from phenylacetylene and propargyl alcohol. The palladacycle precatalyst reacts with aryl alkynes to afford the first example of a dimeric palladacycle complex with a μ-κ²-C¹,C¹-bound acetylide ligand. This complex is observed during the catalytic reaction and is a competent precatalyst.