Double-Asymmetric Hydrogenation Strategy for the Reduction of 1,1-Diaryl Olefins Applied to an Improved Synthesis of CuIPhEt, a C2-Symmetric N-Heterocyclic Carbenoid

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• 作者：Elizabeth Spahn ; Abigail Albright ; Michael Shevlin ; Larissa Pauli ; Andreas Pfaltz ; Robert E. Gawley
• 刊名：The Journal of Organic Chemistry
• 出版年：2013
• 出版时间：March 15, 2013
• 年：2013
• 卷：78
• 期：6
• 页码：2731-2735
• 全文大小：282K
• 年卷期：v.78,no.6(March 15, 2013)
• ISSN：1520-6904

文摘

A library of iridium and rhodium phosphine catalysts have been screened for the double-asymmetric hydrogenation of 2,6-di-(1-phenylethenyl)-4-methylaniline to produce the C₂-symmetric aniline precursor of the N-heterocyclic carbenoid CuIPhEt. The best catalyst produced the desired enantiomer in 98.6% selectivity. This rare example of a highly selective hydrogenation of a 1,1-diaryl olefin enables a four-step asymmetric synthesis of the C₂-symmetric phenylethyl imidazolium ion (IPhEt) from p-toluidine and phenylacetylene and its conversion to the hydrosilylation catalyst CuIPhEt.