Facile Pd(II)- and Ni(II)-Catalyzed Isomerization of Terminal Alkenes into 2-Alkenes
作者:Hwan Jung Lim、Craig R. Smith、T. V. RajanBabu
DOI:10.1021/jo900180p
日期:2009.6.19
of [(allyl)PdCl]2 or [(allyl)NiBr]2, a triarylphosphine, and silver triflate at room temperature. The isomeric ratio (E:Z) depends on the alkenes, the E-isomer being the major one. The reaction is tolerant to a wide variety of functional groups including other reactive olefins. Unlike the more reactive Ir catalysts, monosubstituted alkenes give almost exclusively the 2-alkenes. Direct comparison to two
通过用催化量的 [(烯丙基)PdCl] 2或 [(烯丙基)NiBr] 处理单取代和 2,2'-二取代末端烯烃,可以将其异构化为更稳定的内 ( Z )- 和 ( E )-烯烃2 、室温下的三芳基膦和三氟甲磺酸银。异构体比例 ( E : Z ) 取决于烯烃,其中E异构体是主要异构体。该反应可耐受多种官能团,包括其他反应性烯烃。与活性更高的 Ir 催化剂不同,单取代烯烃几乎只生成 2-烯烃。还描述了与该过程中两种最著名的催化剂[Ir(PCy 3 ) 3 ] + [BPh 4 ] -和格拉布第二代复分解催化剂}的直接比较。
Tunable Phosphoramidite Ligands for Asymmetric Hydrovinylation: Ligands par excellence for Generation of All-Carbon Quaternary Centers
作者:T. RajanBabu、Craig Smith、Hwan Lim、Aibin Zhang
DOI:10.1055/s-0029-1216826
日期:2009.6
2′-biphenol are almost as good as ligands derived from the more expensive enantiopure 1,1′-bi(2-naphthol)s. The hydrovinylation products, which carry two versatile latent functionalities, an aryl and a vinyl group, are potentially useful for the synthesis of several important natural products containing benzylic all-carbon quaternarycenters. alkenes - asymmetric catalysis - hydrovinylation - phosphoramidite
The first transition metal-free highly stereoselective positional isomerization of various α-alkyl styrenes through a carbocation mechanism triggered strategy is developed by using Al(OTf)3 as a hidden Brønsted acid catalyst, which provides facile access to value-added acyclic tri- and tetra-substituted alkenes in good yields with high stereoselectivity under mild conditions. The practicality of this
Stereospecific Cross Couplings To Set Benzylic, All-Carbon Quaternary Stereocenters in High Enantiopurity
作者:Qi Zhou、Kelsey M. Cobb、Tianyu Tan、Mary P. Watson
DOI:10.1021/jacs.6b08075
日期:2016.9.21
Asymmetric preparation of all-carbonquaternarystereocenters is an important goal. Despite advances in formation of highly enantioenriched products with quaternarystereocenters proximal to a functional group, methods to install quaternarystereocenters isolated from functional groups are limited. Transition metal catalysis offers a potential solution, but prior cross couplings are limited to allylic
全碳四元立体中心的不对称制备是一个重要目标。尽管在形成具有接近官能团的四元立体中心的高度对映体富集的产品方面取得了进展,但安装与官能团分离的四元立体中心的方法是有限的。过渡金属催化提供了一种潜在的解决方案,但先前的交叉偶联仅限于烯丙基底物或几乎没有提供对映体富集。我们报告了立体定向的、镍催化的叔苄基乙酸酯的 Suzuki-Miyaura 芳基化,以高产率和 ee 提供具有二芳基和三芳基四元立体中心的产物。该反应使用廉价、空气稳定的 Ni(II) 盐和市售的膦配体来转化叔醇衍生物,这些衍生物很容易以特殊的 ee、
Coplanarity Effects on the Spectral, Gas Chromatographic, Polarographic, and Diels-Alder Characteristics of 1-Alkyl-1-(2-naphthyl)ethenes<sup>1</sup>