Pd-Catalyzed Inter- and Intramolecular Carbene Transfer from Group 6 Metal−Carbene Complexes<sup>1</sup>
作者:Miguel A. Sierra、Juan C. del Amo、María J. Mancheño、Mar Gómez-Gallego
DOI:10.1021/ja002497i
日期:2001.2.1
intramolecular carbene transfer reactions has been studied. Thus, pentacarbonyl[(aryl)(methoxy)carbene]chromium(0) and tungsten complexes, 10, efficiently dimerize at room temperature in the presence of diverse Pd(0) and Pd(II)/Et(3)N catalysts. The effect of additives (PPh(3), AsPh(3), or SbPh(3)) on the nature and the isomeric ratio of the reaction products is negligible. The nature of the reaction products
Control over the <i>E</i>/<i>Z</i> Selectivity of the Catalytic Dimerization of Group 6 (Fischer) Metal Carbene Complexes
作者:Gong M. Chu、Israel Fernández、Miguel A. Sierra
DOI:10.1021/jo302130h
日期:2013.2.1
additives in the reaction of self-dimerization of alkoxychromium(0) (Fischer) carbenecomplexes resulted in the selection of Pd(PtBu3)2 to effect this transformation with good to excellent E selectivities and acceptable to excellent chemical yields. This catalyst will allow the control of the geometry in the synthesis of polyconjugated olefins, one emerging application of these catalytic reactions.
对烷氧基铬(0)(Fischer)卡宾配合物自二聚反应中不同催化剂和添加剂的影响进行系统研究后,选择了Pd(P t Bu 3)2来实现具有良好或优异E的转化。选择性和优良的化学收率是可以接受的。该催化剂将允许控制聚共轭烯烃的合成中的几何形状,这些催化反应的一种新兴应用。
Quasi-template effect: a tool for controlling stereochemistry in acyclic systems. Attempted stereoselective synthesis of α,α′-dimethoxystilbene
作者:Yoshihisa Inoue、Hirokazu Ikeda、Tadao Hakushi
DOI:10.1039/p29860000259
日期:——
reaction of benzoin with a series of alkali-metal hydroxides in THF, gave (E)- and (Z)-α,α′-dimethoxystilbenes as the major products in most cases, the E:Z ratio of which varies from 0.4 to 5.0 depending upon the alkali-metal cation employed; the results are rationalized in the quasi-templateeffect in an acyclicsystem and the hard–soft ion principle.
The invention relates to novel compounds denominated halocombstatins. The halocombstatins are derivatives of combretastatin A-3, and include compounds that exhibit cancer growth cell inhibition against a panel of human cancer cell lines and the murine P388 leukemia, as well as activity as inhibitors of tubulin polymerization and inhibitors of the binding of colchicine to tubulin.
Distilled tall oil fatty acids are improved by irradiation which isomerizes trans-dimethoxystilbene (trans-DMS) impurity to cis-dimethoxystilbene which is easily removed by fractional distillation. Thus, the trans-DMS is removed without loss of fatty acid components from the distilled tall oil fatty acid.