Asymmetric Hydrogenation of Unsaturated Ureas with the BIPI Ligands

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• 作者：Carl A. Busacca ; Jon C. Lorenz ; Nelu Grinberg ; Nizar Haddad ; Heewon Lee ; Zhibin Li ; Mary Liang ; Diana Reeves ; Anjan Saha ; Rich Varsolona ; Chris H. Senanayake
• 刊名：Organic Letters
• 出版年：2008
• 出版时间：January 17, 2008
• 年：2008
• 卷：10
• 期：2
• 页码：341 - 344
• 全文大小：70K
• 年卷期：v.10,no.2(January 17, 2008)
• ISSN：1523-7052

文摘

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Asymmetric hydrogenation of unsaturated urea esters with the BIPI Ligands has been examined. Optimization of the P-N ligand structure hasled to the development of chiral rhodium catalysts capable of producing the targets with >99% ee. The critical phosphine borane S_NAr reactionneeded for ligand synthesis has been optimized to give the adducts in high yield at ambient temperature with no racemization. An extremelyconcise, economical, and scalable sequence to these important new ligands for catalysis of asymmetric hydrogenation has been developed.