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
Enantioselective Conjugate Addition of Hydrazines to α,β-Unsaturated Imides. Synthesis of Chiral Pyrazolidinones
作者:Mukund P. Sibi、Takahiro Soeta
DOI:10.1021/ja069312d
日期:2007.4.1
This manuscript describes a highlyenantioselectiveconjugate hydrazine addition to α,β-unsaturatedimides. The achiral template used has a significant impact on product enantioselectivity. Reactions at lower temperatures provide a protocol to add substituted hydrazines with selectivity resulting in the formation of a single pyrazolidinone product (>98:2 selectivity). A variety of chiral pyrazolidinones
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.
Highly Enantioselective, Catalytic Conjugate Addition of Cyanide to α,β-Unsaturated Imides
作者:Glenn M. Sammis、Eric N. Jacobsen
DOI:10.1021/ja034635k
日期:2003.4.1
(Salen)Al−Cl complex 1a catalyzes the asymmetric conjugate addition of hydrogen cyanide to α,β-unsaturated imides in high yields and enantioselectivities. The cyanide adducts can readily be converted into a variety of useful chiralbuildingblocks, including α-substituted-β-amino acids and β-substituted-γ-aminobutyric acids. Mechanistic data obtained thus far point to a cooperative bimetallic mechanism
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。