Hydrogenation of Quinaldine and Benzylic Aldehydes both Separately and Combined in a Tandem Hydrogenation鈥揜eductive Alkylation of Quinaldine by Aldehydes with Iridium Benzoquinoline Catalysts

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• 作者：Michael G. Manas ; Jonathan Graeupner ; Laura J. Allen ; Graham E. Dobereiner ; Kerry C. Rippy ; Nilay Hazari ; Robert H. Crabtree
• 刊名：Organometallics
• 出版年：2013
• 出版时间：August 26, 2013
• 年：2013
• 卷：32
• 期：16
• 页码：4501-4506
• 全文大小：270K
• 年卷期：v.32,no.16(August 26, 2013)
• ISSN：1520-6041

文摘

A series of cyclometalated benzoquinoline complexes of Ir(III) catalyze the hydrogenation of the heterocyclic ring of quinolines under mild conditions. Our best catalyst is active in a significantly wider range of solvents than our previous systems. In the presence of a suitable base, the Ir(III) species is also able to hydrogenate the C鈺怬 bonds of aldehydes. When quinolines and aldehydes are present together, the Ir(III) complex catalyzes a tandem reaction in which the quinoline is first hydrogenated to a tetrahydroquinoline that is subsequently reductively alkylated by the aldehyde. The reductive alkylation competes with the hydrogenation of the aldehyde to the alcohol, and therefore good yields of the alkylated tetrahydroquinoline require the presence of excess aldehyde.