Chiral alkoxy-imidazolinium salts are easily available via a five-step procedure starting from β-aminoalcohols. This new family of alkoxy-N-heterocyclic carbene (NHC) precursors is shown to be highly active in the enantioselective copper-catalysed conjugateaddition to cyclic enones. Complete conversion with lowcatalystloading and good enantiomeric excesses up to 93% were obtained at room temperature
The Cu-catalyzed asymmetric conjugate addition with chiral diphosphite ligands derived from <scp>D</scp>-(-)-tartaric acid
作者:Zeng-Bo Pang、Mi Tian、Hai-Feng Li、Lai-Lai Wang
DOI:10.1080/00397911.2016.1278231
日期:2017.3.19
diphosphite ligands, which were derivedfrom D-(-)-tartaric acid, have been synthesized and successfully applied in the Cu-catalyzed asymmetric conjugate addition of organozincs to enones. There was a synergic effect between the stereogenic centers of the D-(-)-tartaric acid skeleton and the axially H8-binaphthyl moieties of ligand 2c. And ligand 2c shows a comparative catalytic performance to ligand 1-N-benzylpyrrolidine-3
Design of Chiral Hydroxyalkyl‐ and Hydroxyarylazolinium Salts as New Chelating Diaminocarbene Ligand Precursors Devoted to Asymmetric Copper‐Catalyzed Conjugate Addition
The design and the synthesis of a set of new chiral hydroxyalkyl- and hydroxyaryl-chelating diaminocarbene ligands is reported. Comparative catalytic studies show the importance of the scaffold design around the NHC unit to obtain a high enantiocontrol in Cu-catalyzed asymmetricconjugateaddition (ACA). Whereas low selectivities are observed when the stereogenic centre is placed within the N-heterocyclic
Asymmetric Conjugate Addition of Grignard Reagents to Pyranones
作者:Bin Mao、Martín Fañanás-Mastral、Ben L. Feringa
DOI:10.1021/ol303141x
日期:2013.1.18
efficient enantioselectivesynthesis of lactones was developed based on the catalyticasymmetricconjugateaddition (ACA) of alkyl Grignard reagents to pyranones. The use of 2H-pyran-2-one for the first time in the ACA with Grignard reagents allows for a variety of further transformations to access highly versatile building blocks such as β-alkyl substituted aldehydes or β-bromo-γ-alkyl substituted alcohols
基于烷基格氏试剂向吡喃酮的催化不对称共轭加成(ACA),开发了内酯的有效对映选择性合成。带有Grignard试剂的ACA中首次使用2 H -pyran-2-one可以进行多种进一步的转化,以得到高度通用的结构单元,例如β-烷基取代的醛或β-溴-γ-烷基取代的具有出色的区域选择性和立体选择性的醇。
Chiral phosphine–phosphite ligands in the enantioselective 1,4-addition of Grignard reagents to α,β-unsaturated carbonyl compounds
作者:Qaseem Naeemi、Tobias Robert、Darius P. Kranz、Janna Velder、Hans-Günther Schmalz
DOI:10.1016/j.tetasy.2011.04.018
日期:2011.4
phosphine–phosphite ligands was evaluated in the Cu-catalyzed asymmetric 1,4-addition of Grignard reagents to cyclopentenone, cycloheptenone and 5,6-dihydro-2H-pyran-2-one. TADDOL-based ligands 1a and 1b with a bulky substituent at the ortho-position to the chiral phosphite moiety gave rise to the 1,4-addition products with high enantioselectivities (up to 93% ee). In addition to ethyl-MgBr (as a standard