Nickel-Catalyzed Enantioselective Synthesis of Pre-Differentiated Homoallylic <i>syn</i>- or <i>anti</i>-1,2-Diols from Aldehydes and Dienol Ethers
作者:Thomas Q. Davies、John J. Murphy、Maxime Dousset、Alois Fürstner
DOI:10.1021/jacs.1c07042
日期:2021.9.1
Nickelcatalysis allied with cyclodiphosphazane or VAPOL-derived phosphoramidite ligands provides selective access to monoprotected vicinal diols by reductive coupling of dienol ethers and aldehydes. The observed regioselectivity is unprecedented, in that the diene reacts at the least nucleophilic and most hindered C atom that is attached to the oxygen substituent rather than at the terminal position
镍催化与环二磷氮烷或 VAPOL 衍生的亚磷酰胺配体结合,通过二烯醇醚和醛的还原偶联提供对单保护的邻二醇的选择性访问。观察到的区域选择性是前所未有的,因为二烯在亲核性最低且受阻最大的 C 原子上反应,该 C 原子连接到氧取代基而不是在末端位置。值得注意的是,产品的顺式和反式非对映异构体都可以根据二烯伙伴的配置获得,通常具有出色的非对映选择性和对映选择性。
Polysilylated Organosilane Compounds
申请人:CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE (C.N.R.S)
公开号:US20150218192A1
公开(公告)日:2015-08-06
The invention concerns a mono- or polyfunctional polysilylated organosilane compound, and the method for preparing same.
A Mechanistic Investigation of the Asymmetric Meerwein−Schmidt−Ponndorf−Verley Reduction Catalyzed by BINOL/AlMe<sub>3</sub>Structure, Kinetics, and Enantioselectivity
作者:Christopher R. Graves、Hongying Zhou、Charlotte L. Stern、SonBinh T. Nguyen
DOI:10.1021/jo070563u
日期:2007.11.1
[Graphics]The kinetics of the Al-catalyzed asymmetric Meerwein-Schmidt-Ponndorf-Verley (MSPV) reduction are presented. Structural identification of the catalytic precursor formed in situ between (S)-2,2'-dihydroxy-1,1'-binapthyl ((S)-BINOL), AlMe3, and 2-propanol was established through H-1 and Al-27 NMR spectroscopies, and APCIMS. All experimental evidence points toward the formation of a BINOL-chelated, pentacoordinate aluminum species in solution. Ligand-accelerated catalysis was confirmed for the phenol ate/AlMe3/2-propanol system. The rate law for the catalytic reaction was determined to be nearly unimolecular dependent on aluminum, zero-order dependent on substrate, and inversely dependent on 2-propanol. At the low catalyst loading employed in the BINOL/AlMe3 system, the inherent reversibility of the MSPV reaction does not affect product yield or enantiomeric excess over time. Systematic ligand studies imply that while a tetrahedral geometry around the aluminum center may result in the most active MSPV reduction catalysts, the enantioselectivity of the reaction is enhanced when the aluminum center allows for a 2-point coordination of the substrate to achieve a pentacoordinate geometry with the fifth ligand weakly coordinated to the axial site of a pseudo square pyramid.