Ruthenium-Catalyzed Regioselective 1,4-Hydroboration of Pyridines

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• 作者：Akash Kaithal ; Basujit Chatterjee ; Chidambaram Gunanathan
• 刊名：Organic Letters
• 出版年：2016
• 出版时间：July 15, 2016
• 年：2016
• 卷：18
• 期：14
• 页码：3402-3405
• 全文大小：387K
• 年卷期：0
• ISSN：1523-7052

文摘

Simple ruthenium precursor [Ru(p-cymene)Cl₂]₂ 1 catalyzed regioselective 1,4-dearomatization of pyridine derivatives using pinacolborane is reported. Two catalytic intermediates, [Ru(p-cymene)Cl₂Py] 2 and [Ru(p-cymene)Cl₂(P(Cy)₃)] 3, involved in this process are identified, independently synthesized, characterized, and further used directly as effective catalysts; two more catalytic intermediates [Ru(p-cymene)Cl₂(Py)(P(Cy)₃)] 4 and [Ru(p-cymene)(H)Cl(Py)(P(Cy)₃)] 5 are identified in solution. Complex 5 is the active catalytic intermediate. An intramolecular selective 1,5-hydride transfer in 5 leading to the regioselective 1,4-hydroboration of pyridine compounds is proposed.