Enantioselective Ni–Al Bimetallic Catalyzed exo-Selective C–H Cyclization of Imidazoles with Alkenes
摘要:
A Ni-Al bimetallic catalyzed enantioselective C-H exo-selective cyclization of imidazoles with alkenes has been developed. A series of bi- or polycyclic imidazoles with beta-stereocenter were obtained in up to 98% yield and >99% ee. The bifunctional SPO ligand-promoted bimetallic catalysis proved to be critical to this challenging stereocontrol.
A New, Short, and Stereocontrolled Synthesis of <i>C</i><sub>2</sub>-Symmetric 1,2-Diamines
作者:Rajender Vemula、Nathan C. Wilde、Rajendar Goreti、E. J. Corey
DOI:10.1021/acs.orglett.7b01768
日期:2017.7.21
reaction of ammonia, glyoxal hydrate, and cyclohexanone. It is a very useful precursor for the diastereocontrolled synthesis of many C2-symmetric 1,2-diamines, a class which is important for the generation of a variety of C2-symmetric reagents and catalysts for enantioselective synthesis.
Highly active asymmetric Diels–Alder reactions catalyzed by C2-symmetric bipyrrolidines: catalyst recycling in water medium and insight into the catalytic mode
designed and synthesized for asymmetric organocatalytic Diels–Alder reactions of α,β-unsaturatedaldehydes. The remarkable rate-accelerating effect for the cycloaddition reaction has been observed in aqueous medium. The catalyst 1c·2HClO4 can be recovered and reused several times by simple extraction without significant loss of catalytic activity and stereoselectivity. The catalytic mode has been demonstrated
Titanium(IV)(salen) and Vanadium(V)(salen) Complexes Derived from<i>C</i><sub>2</sub>- and<i>C</i><sub>1</sub>-Symmetric Diamines for Asymmetric Cyanohydrin Synthesis
作者:Michael North、Yuri Belokon’、Jamie Hunt
DOI:10.1055/s-2008-1077900
日期:2008.8
Titanium and vanadium salen complexes have been prepared from C 2 - and Ci-symmetric acyclic diamines. All of the complexes catalysed the asymmetric addition of trimethylsilyl cyanide to benzaldehyde and the sense of asymmetric induction was determined by the nature of the substituents. The vanadiumcomplex of a valine-derived diamine gave good results with a range of aromatic and aliphatic aldehydes
Synthesis of Chiral C2-Symmetric 1,2-Diamines by the Addition of Organolithium Reagents to N,N′-Bis[(S)-1-phenylethyl]ethanediimine
作者:Gianluca Martelli、Stefano Morri、Diego Savoia
DOI:10.1016/s0040-4020(00)00782-1
日期:2000.10
The additions of alkyl-, phenyl- and vinyllithium reagents to N,N′-bis[(S)-1-phenylethyl]ethanediimine in THF at −78°C and in DME at −60°C gave high yields of 1,2-diamines with low stereocontrol. Care was taken to quench the reaction mixtures with de-aerated H2O to avoid formation of N-alkylidene-1-phenylethylamines which were formed through homolysis of the dilithium 1,2-diamides to give α-amido radicals
在-78°C的THF中和在-60°C的DME中,向N,N'-双[(S)-1-苯基乙基]乙二亚胺中添加烷基,苯基和乙烯基锂试剂可得到1,2的高收率-低立体控制的二胺。小心地用脱气的H 2 O淬灭反应混合物,以避免形成N-亚烷基-1-苯基乙胺,后者是通过1,2-二酰胺二锂的均质化反应生成的α-酰胺基与O 2反应而形成的。/ H 2 O在淬灭步骤中。戊二烯基-,肉桂基-和1-三甲基甲硅烷基烯丙基锂试剂仅以高收率和中等至良好的非对映选择性提供线性1,2-二胺。
Synthesis, structure, and reaction of chiral 2-azidoimidazolinium salts: (7aS)-3-azido-5,6,7,7a-tetrahydro-2-[(1R)-1-phenylethyl]-1H-pyrrolo[1,2-c]imidazolium hexafluorophosphate and 2-azido-1,3-bis[(S)-1-phenylethyl]imidazolinium hexafluorophosphate
Two chiral 2-azidoimidazolinium salts [(7aS)-3-azido-5,6,7,7a-tetrahydro-2-[(1R)-1-phenylethyl]-1H-pyrrolo[1,2-c]imidazolium hexafluorophosphate (2) and 2-azido-1,3-bis[(S)-1-phenylethyl]imidazolinium hexafluorophosphate (3)] were synthesized, and their structures were determined by X-ray single crystal structural analysis. Migratory amidation reaction of enol silyl ether with 3 proceeded, but good
两种手性2-叠氮基咪唑啉盐[(7a S)-3-叠氮基-5,6,7,7a-四氢-2-[(1 R)-1-苯乙基] -1 H-吡咯并[1,2- c ]合成了咪唑六氟磷酸盐(2)和2-叠氮基1,3-双[(S)-1-苯基乙基]咪唑啉六氟磷酸盐(3)],并通过X射线单晶结构分析确定了它们的结构。烯醇甲硅烷基醚与3进行迁移性酰胺化反应,但是在反应中未观察到良好的非对映选择性。