Enantioselective Formal Hydration of α,β-Unsaturated Imides by Al-Catalyzed Conjugate Addition of Oxime Nucleophiles
作者:Christopher D. Vanderwal、Eric N. Jacobsen
DOI:10.1021/ja045563f
日期:2004.11.1
(salen)Al-catalyzed asymmetric conjugate addition of salicylaldoxime to α,β-unsaturated imides is the key step in an efficient and highly enantioselective two-step formal hydration of these electron-deficient olefins. This reaction constitutes the first example of an enantioselective conjugate addition of an oxygen-centered nucleophile to α,β-unsaturated carboxylic acid derivatives. Application of this method
Enantioselective Michael Additions to α,β-Unsaturated Imides Catalyzed by a Salen−Al Complex
作者:Mark S. Taylor、Eric N. Jacobsen
DOI:10.1021/ja037177o
日期:2003.9.1
conjugate addition of di- and trisubstituted nitriles to a wide range of acyclic alkyl- and aryl-substituted α,β-unsaturated imides. This new methodology provides access to multifunctional compounds that previously have not been readily accessible in enantioenriched form. Synthetic applications of these products include the preparation of enantiomerically enriched piperidines, as exemplified by an expedient
Bifunctional chiral organocatalysts comprising thiourea and tertiaryamine groups were synthesized. They act as efficientcatalysts for asymmetric Michaeladdition of arylthiols to alpha,beta-unsaturated carbonyl compounds. Enantioselectivity up to 85% has been achieved. Asymmetric alpha-protonation reaction (up to 60% ee) can be obtained in the presence of the bifunctionalcatalyst.
Cooperative Dual Catalysis: Application to the Highly Enantioselective Conjugate Cyanation of Unsaturated Imides
作者:Glenn M. Sammis、Hiroshi Danjo、Eric N. Jacobsen
DOI:10.1021/ja046653n
日期:2004.8.1
Cooperative heterobimetallic catalysis was used as a design principle to achieve a highly reactive system for the enantioselective conjugate addition of cyanide to alpha,beta-unsaturated imides. A dual-catalyst pathway involving chiral (salen)Al complex 1b and chiral (pybox)Er complex 4b provides measurable improvements in rates and enantioselectivities relative to single-catalyst systems. Mechanistic
协同异双金属催化被用作设计原理,以实现氰化物对映选择性共轭加成到 α,β-不饱和酰亚胺的高反应性系统。涉及手性 (salen)Al 配合物 1b 和手性 (pybox)Er 配合物 4b 的双催化剂途径提供了相对于单催化剂系统的速率和对映选择性的可测量改进。机理研究指出了一种协同双金属机制,包括通过 Al 配合物激活酰亚胺和通过 Er 配合物激活氰化物。
Enabling Ligand Screening for Palladium-Catalysed Enantioselective Aza-Michael Addition Reactions
作者:Pim Huat Phua、Andrew J. P. White、Johannes G. de Vries、King Kuok (Mimi) Hii
DOI:10.1002/adsc.200505404
日期:2006.3
palladium(II) precursor for the generation of dicationic palladium(II) catalysts. Parallel ligandscreening is enabled for the first time, and twenty-four chiral ligands were evaluated for the asymmetric aza-Michaeladdition of aromatic amines to α,β-unsaturated N-alkenoylimides and carbamates. Enantioselectivities of >99% can be obtained. Catalytic precursors generated from 1 using the new protocol have