Enantioselective rhodium-catalyzed hydrogenation of enol carbamates in the presence of monodentate phosphines

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• 作者：Stephan Enthaler ; Giulia Erre ; Kathrin Junge ; Dirk Michalik ; Anke Spannenberg ; Fabrizio Marras ; Serafino Gladiali ; Matthias Beller
• 关键词：Cyclizations ; Heterocycles ; Medium-sized rings ; Ring-closing metathesis ; Silyl enol ethers
• 刊名：Tetrahedron: Asymmetry
• 出版年：2007
• 出版时间：22 June 2007
• 年：2007
• 卷：18
• 期：11
• 页码：1288-1298
• 全文大小：388 K

文摘

The rhodium-catalyzed asymmetric hydrogenation of different acyclic and cyclic enol carbamates to give optically active carbamates has been examined in the presence of chiral monodentate ligands based on a 4,5-dihydro-3H-dinaphthophosphepine motif 4. The enantioselectivity is largely dependent upon the reaction conditions, the nature of substituents on the phosphorus ligand and structure of the enol carbamate. By applying the optimized reaction conditions, enantioselectivities of up to 96 % ee have been achieved.