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
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。
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
Palladium-Catalysed Enantioselective Conjugate Addition of Aromatic Amines to α,β-UnsaturatedN-Imides. Effect of the Chelating Moiety
作者:Pim Huat Phua、Johannes G. de Vries、King Kuok (Mimi) Hii
DOI:10.1002/adsc.200505126
日期:2005.11
Palladium-catalysedenantioselectiveadditions of aromaticamines to α,β-unsaturated N-imides 4–6 are reported. The N-substituent of the Michael acceptor appears to have an unusual modulating effect on the amine activity. The effects of introducing different substituents are examined. Overall, the yield and selectivity of the system appear to be less sensitive to environmental effects than previous