Influences of Electronic Effects and Anions on the Enantioselectivity in the Oxazaborolidine-Catalyzed Asymmetric Borane Reduction of Ketones
作者:Xu、Wei、Zhang
DOI:10.1021/jo048959i
日期:2004.10.1
influence of electronic effects on the enantioselectivity of the oxazaborolidine-catalyzedasymmetricboranereduction of ketones has been observed and investigated with use of para-substituted acetophenones and propiophenones with a variety of functional groups and B-unsubstituted and B-methoxyoxazaborolidines derived from (S)-2-(diphenylhydroxymethyl)pyrrolidine with borane and trimethyl borate as catalysts
Chiral bis(amino alcohol)oxalamides as ligands for asymmetric catalysis. Ti(IV) catalyzed enantioselective addition of diethylzinc to aldehydes
作者:Gonzalo Blay、Isabel Fernández、Alícia Marco-Aleixandre、José R. Pedro
DOI:10.1016/j.tetasy.2005.01.039
日期:2005.3
Several chiral bis(aminoalcohol)oxalamides with C2-symmetry have been prepared and used as ligands for the enantioselectiveaddition of diethylzinc to aromatic and aliphatic aldehydes. The reaction proceeds in the presence of titanium isopropoxide to give the corresponding (S)-alcohols with ee up to 78%. In the absence of Ti(IV), the alcohols with the opposite configuration are obtained.
2-Amino-Substituted 1-Sulfinylferrocenes as Chiral Ligands in the Addition of Diethylzinc to Aromatic Aldehydes
作者:Julián Priego、Olga García Mancheño、Silvia Cabrera、Juan Carlos Carretero
DOI:10.1021/jo016271p
日期:2002.2.1
ferrocenyl sulfoxides and their use as chiral catalysts in the asymmetric addition of diethylzinc to aromaticaldehydes is described. Moderate to high enantioselectivities (up to 96% ee) were obtained in the case of the arylsulfonamide ligands (R(Fc), R(S))-4h and (R(Fc), R(S))-4i. It has been demonstrated that the planar chirality of the ferrocene unit is the decisive chiral element involved in the reaction
Synthesis of Novel 1,4-Bissulfonamide Ligands for Enantioselective Addition of Diethylzinc to Aldehydes
作者:Minghua Yang、Jiangtao Sun、Chengjian Zhu
DOI:10.1002/cjoc.201180303
日期:2011.8
Several novel chiral sulfonamide ligands based on (1R,2S,4R,5S)‐1,4‐diamino‐2,5‐dimethylcyclohexane skeleton have been synthesized and their application in the enantioselective addition of diethylzinc to aldehydes was investigated in the presence of Ti(OiPr)4. The effect of ligands, temperature and the loading amount of ligands was studied. Under optimized conditions, enantioselective addition of diethylzinc
合成了几种基于(1 R,2 S,4 R,5 S)-1,4-二氨基-2,5-二甲基环己烷骨架的新型手性磺酰胺配体,并研究了它们在二乙基锌对醛的对映选择性加成中的应用。 Ti(O i Pr)4的存在。研究了配体的影响,温度和配体的负载量。在最佳条件下,二乙基锌与各种芳基醛和脂族醛的对映选择性加成反应顺利进行,并提供了高达88%ee的手性仲醇。
Preparation and Application of Polymer-Grafted Ti–BINOL Complexes as Chiral Catalysts in the Enantioselective Addition of Diethylzinc to Aldehydes
BINOL respectively. The resulting functionalized polymers 4 and 7 have been used as chiral ligands in the Ti-catalytic enantioselectiveaddition of diethylzinc to aldehydes. Compared with the homogeneous ligands 5 and 8 in the same reaction, the polymer-supported ligands 4 and 6 gave, in some cases, higher enantioselectivity. The conformational inflexibility of the ligands was analyzed to illustrate the