Catalytic Direct Arylation with Aryl Chlorides, Bromides, and Iodides: Intramolecular Studies Leading to New Intermolecular Reactions

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• 作者：Louis-Charles Campeau ; Mathieu Parisien ; Annie Jean ; and Keith Fagnou
• 刊名：Journal of the American Chemical Society
• 出版年：2006
• 出版时间：January 18, 2006
• 年：2006
• 卷：128
• 期：2
• 页码：581 - 590
• 全文大小：302K
• 年卷期：v.128,no.2(January 18, 2006)
• ISSN：1520-5126

文摘

A catalyst for the intramolecular direct arylation of a broad range of simple and heterocyclicarenes with aryl iodides, bromides, and chlorides has been developed. These reactions occur in excellentyield and are highly selective. Studies with aryl iodides substrates revealed that catalyst poisoning occursdue to the accumulation of iodide in the reaction media. This can be overcome by the addition of silversalts which also permits these reactions to occur at lower temperature. The utility of the methodology isillustrated by a rapid synthesis of a carbazole natural product and by the synthesis of sterically encumberedtetra-ortho-substituted biaryls via ring-opening reactions of the direct arylation products. Mechanisticinvestigations have provided insight into the catalyst's mode of action and show the presence of a kineticallysignificant C-H bond cleavage in palladium-catalyzed direct arylation of simple arenes. Knowledge garneredfrom these studies has led to the development of new intermolecular arylation reactions with previouslyinaccessible arenes, opening the door for the development of other new direct arylation processes.