已经研究了苄胺和硼酸酯之间的偶联反应。邻-Lithiated苄胺与硼酸酯反应,并且一个Ñ -activator,得到邻位与正规1,1'-亚苄基取代的插入苄硼酸酯到C-B键。该反应通过S N 2'的消除和N活化的硼酸酯络合物的1,2-金属化物重排而得到脱芳香化的中间体,该中间体经过路易斯酸催化的1,3-硼向转变以得到硼酸酯产物。高收率和优异的对映体特异性。使用富含对映体的α-取代的苄胺得到相应的具有高ee的仲硼酸酯。
Asymmetric reduction of aliphatic ketones and acyl silanes using chiral anti-pentane-2,4-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid
Aliphatic ketones were reduced to the corresponding secondaryalcohols by using anti-1,3-diol and a catalytic amount of 2,4-dinitrobenzenesulfonic acid (DNBSA) in benzene at reflux. Addition of 1-octanethiol in that media improved the efficiency of the reduction. Asymmetric reduction of aliphatic ketones was performed by using chiral anti-pentane-2,4-diol, and highly asymmetric induction (up to >99%
Highly enantioselective addition of dialkylzincs to aldehydes using dendritic chiral catalysts with flexible carbosilane backbones
作者:Itaru Sato、Ryo Kodaka、Kenji Hosoi、Kenso Soai
DOI:10.1016/s0957-4166(02)00203-3
日期:2002.5
Chiral dendrimers bearing four or twelve chiral β-amino alcohols on the hyperbranched flexible carbosilane chain-ends act as efficient chiral catalysts for the enantioselectiveaddition of dialkylzinc to aldehydes to afford enantiomerically enriched sec-alcohols with up to 93% e.e.
Facile synthesis of chiral isopropyl carbinols with high enantiomeric excess via catalytic enantioselective addition of diisopropylzinc to aldehydes
作者:Weon Ki Yang、Byung Tae Cho
DOI:10.1016/s0957-4166(00)00253-6
日期:2000.7
Highly effective syntheses of chiral alkyl and aryl isopropyl carbinols with highenantiomericexcess (94–98% ee) via catalytic enantioselective addition of diisopropylzinc to aldehydes have been developed.
Application of well-defined chain-end-functionalized polystyrenes with dendritic chiral ephedrine moieties as reagents for highly catalytic enantioselective addition of dialkylzincs to aldehydes
作者:Ashraf A. El-Shehawy、Kenji Sugiyama、Akira Hirao
DOI:10.1016/j.tetasy.2007.12.020
日期:2008.3
having a definite number of chiral ephedrine moieties dendritically distributed at the periphery of their hyperbranched chain-ends were evaluated as chiral catalysts for the enantioselectiveaddition of dialkylzinc reagents to aldehydes. These dendritic macromolecules worked well as homogeneous chiral catalysts and exhibited high catalytic activity and enantioselectivity very similar to those observed
Stereospecific Reaction of α-Carbamoyloxy-2-alkenylboronates and α-Carbamoyloxy-alkylboronates with Grignard Reagents - Synthesis of Highly Enantioenriched Secondary Alcohols
作者:Dieter Hoppe、Edith Beckmann、Vidya Desai
DOI:10.1055/s-2004-832835
日期:——
Highly enantioenriched secondary alcohols were synthesized by treatment of α-carbamoyloxy-2-alkenylboronates and α-carbamoyloxy-alkylboronates with Grignard reagents. An intermediary boronate complex was transformed stereospecifically to the corresponding secondary 2-alkenyl- and alkylboronates by migration of an introduced residue. Oxidative workup furnished the enantioenriched secondary alcohols.