Organocatalyzed asymmetric Michael addition by an efficient bifunctional carbohydrate–thiourea hybrid with mechanistic DFT analysis
作者:Chandra S. Azad、Imran A. Khan、Anudeep K. Narula
DOI:10.1039/c6ob02158a
日期:——
core scaffold were synthesized and examined as catalysts for the asymmetricMichael addition reaction of aryl/alkyl trans-β-nitrostyrenes over cyclohexanone and other Michael donors having active methylene. Excellent enantioselectivities (<95%), diastereoselectivities (<99%), and yields (<99%) were attained undersolvent free conditions using 10 mol% of 1d0. The obtained results were explained through
Goldberg Active Template Synthesis of a [2]Rotaxane Ligand for Asymmetric Transition-Metal Catalysis
作者:Steven Hoekman、Matthew O. Kitching、David A. Leigh、Marcus Papmeyer、Diederik Roke
DOI:10.1021/jacs.5b04726
日期:2015.6.24
report on the active template synthesis of a [2]rotaxane through a Goldberg copper-catalyzed C-N bond forming reaction. A C2-symmetric cyclohexyldiamine macrocycle directs the assembly of the rotaxane, which can subsequently serve as a ligand for enantioselective nickel-catalyzed conjugate addition reactions. Rotaxanes are a previously unexplored ligand architecture for asymmetriccatalysis. We find that
Scope and Mechanism of Enantioselective Michael Additions of 1,3-Dicarbonyl Compounds to Nitroalkenes Catalyzed by Nickel(II)−Diamine Complexes
作者:David A. Evans、Shizue Mito、Daniel Seidel
DOI:10.1021/ja0735913
日期:2007.9.1
Readily prepared Ni(II)-bis[(R,R)-N,N'-dibenzylcyclohexane-1,2-diamine]Br(2) was shown to catalyze the Michaeladdition of 1,3-dicarbonyl compounds to nitroalkenes at room temperature in good yields with high enantioselectivities. The two diamineligands in this system each play a distinct role: one serves as a chiralligand to provide stereoinduction in the addition step while the other functions
容易制备的 Ni(II)-双[(R,R)-N,N'-二苄基环己烷-1,2-二胺]Br(2) 在室温下可催化 1,3-二羰基化合物与硝基烯烃的迈克尔加成反应温度高,产率高,对映选择性高。该系统中的两个二胺配体各自发挥不同的作用:一个作为手性配体在加成步骤中提供立体诱导,而另一个作为底物烯醇化的基础。还研究了催化剂内的配体改性,以促进脂肪族硝基烯烃、1,3-二酮和 β-酮酸的反应。Ni(II)-双[(R,R)-N,N'-di-p-bromo-benzylcyclohex-1,2-diamine]Br(2) 在这些情况下被发现是一种有效的催化剂。此外,单二胺络合物,Ni(II)-[(R,R)-N,N'-二苄基环己烷-1,2-二胺]Br(2),在水存在下催化加成反应。所提出的立体化学诱导模型显示与 X 射线结构分析一致。
Redox-configurable ambidextrous catalysis: structural and mechanistic insight
作者:Shahab Mortezaei、Noelle R. Catarineu、Xueyou Duan、Chunhua Hu、James W. Canary
DOI:10.1039/c5sc02144h
日期:——
A helically chiral copper complex is used as a switchable asymmetric catalyst capable of delivering either enantiomer of a Michael addition reaction.
一个螺旋手性铜配合物被用作可切换的不对称催化剂,能够提供Michael加成反应的任一对映体。
Polysulfonate supported chiral diamine-nickel catalysts: Synthesis and applications
A series of chiral polysulfonate cyclohexyldiamine-Ni(II) catalysts were prepared via sulfur (VI) fluoride exchange click-reactions. The catalysts exhibited good catalytic activity and enantioselectivity in the Michaeladdition of malonates to nitroalkenes. The excellent recyclability of the catalysts was demonstrated via the reuse of the privileged catalyst 7a for ten times. The results provide a