The effects of solvent on switchable stereoselectivity: copper-catalyzed asymmetric conjugate additions using D2-symmetric biphenyl phosphoramidite ligands
A highly enantioselective copper-catalyzed conjugateaddition of diethylzinc to acyclic aromatic enones was developed with phosphoramidite ligands bearing a D2-symmetric biphenyl backbone. This type of reaction demonstrated that toluene and THF solvents can completely reverse the absolute configuration of the products, thus simplifying the process of accessing either enantiomer (S: 92% ee, 94% yield;
Catalytic Asymmetric Transfer Hydrogenation of <i>trans</i>-Chalcone Derivatives Using BINOL-derived Boro-phosphates
作者:Fei Na、Susana S. Lopez、Alice Beauseigneur、Lucas W. Hernandez、Zhuoxin Sun、Jon C. Antilla
DOI:10.1021/acs.orglett.0c02042
日期:2020.8.7
Chiral phosphoric-acid-catalyzed asymmetric reductions of trans-chalcones have been investigated in this work. A BINOL-derived boro-phosphate-catalyzed asymmetric transfer hydrogenation of the carbon–carbon double bond of trans-chalcone derivatives employing borane as a hydride source was realized. This methodology provides a convenient procedure to accesschiral dihydrochalone derivatives in high
Enantioselective Catalytic Conjugate Addition of Dialkylzinc Reagents using Copper–Phosphoramidite Complexes; Ligand Variation and Non-linear Effects
作者:Leggy A Arnold、Rosalinde Imbos、Alessandro Mandoli、André H.M de Vries、Robert Naasz、Ben L Feringa
DOI:10.1016/s0040-4020(00)00142-3
日期:2000.4
cyclohexenone and chalcone in order to assess the structural features that are important for stereocontrol. A sterically demanding amine moiety is essential to reach high e.e.’s. Enantioselectivities for chalcones up to 89% and for cyclic enones up to 98% were found. Studies on non-linear effects with the best ligands for both cyclohexenone and chalcone showed clear non-linear effects for both cyclic
Switchable Stereoselectivity: The Effects of Substituents on the D2-Symmetric Biphenyl Backbone of Phosphoramidites in Copper-Catalyzed Asymmetric Conjugate Addition Reactions with Triethylaluminium
A highly enantioselective copper‐catalyzed conjugateaddition with triethylaluminium was developed using phosphoramidite ligands bearing a D2‐symmetric biphenylbackbone. For these ligands we demonstrated that the 3,3′,5,5′‐substituents on the biphenylbackbone can completely reverse the absolute configuration of the products.
Synthesis of Chiral Amino Alcohols Embodying the Bispidine Framework and Their Application as Ligands in Enantioselectively Catalyzed Additions to CO and CC Groups
course of enantioselective transformations, bispidine amino alcohols built up by these two routes were investigated as chiralligands in the enantioselectively catalyzed addition of diethylzinc to aldehydes and chalcone. In general, tridentate ligands containing one chiral amino alcohol fragment and a second amino substituent without a stereogenic center were more efficient than tetradentate ligands with
已经开发了两种普遍适用的合成包含双吡啶骨架的手性氨基醇的路线。在线性路线 A 中,双吡啶骨架是由手性伯胺通过中间体形成哌啶酮和双吡啶酮依次构建的。在收敛路线 B 中,首先形成非手性双吡啶,然后通过氮碱与手性亲电试剂的反应引入 N-取代基。为了确定双吡啶核心及其 N 取代基是否能影响对映选择性转化的空间过程,研究了通过这两种途径构建的双吡啶氨基醇作为手性配体在二乙基锌对醛和查耳酮的对映选择性催化加成中。一般来说,含有一个手性氨基醇片段和没有立体中心的第二个氨基取代基的三齿配体比具有两个氨基醇结构单元的四齿配体更有效。使用最好的配体,二乙基锌对芳香族和脂肪族醛的对映选择性加成以 83-98% ee 进行,二乙基锌向查耳酮的镍催化加成达到 85% ee。