Central linkage influence upon mesomorphic and electrooptical behavior of diaryl nematics. General proton magnetic resonance method employing a lanthanide shift reagent for analysis of isomeric azoxybenzenes
Stereospecific Iron-Catalyzed Carbon (sp<sup>2</sup>)–Carbon (sp<sup>2</sup>) Cross-Coupling of Aryllithium with Vinyl Halides
作者:Peng Chen、Zhi-Yong Wang、Xiao-Shui Peng、Henry N.C. Wong
DOI:10.1021/acs.orglett.1c01318
日期:2021.6.4
We present herein an efficient synthetic protocol involving iron-catalyzed cross-coupling of organolithium compounds with vinyl halides as key coupling partners. More than 30 examples were obtained with moderate to good yields and high stereoselectivities. The practicality of this method is evidenced by a gram-scale synthesis. In addition, a preliminary mechanistic investigation was also performed
Copper oxidecatalysts have been prepared by pyrolysis of copper acetate on aluminum oxide. The material resulting from pyrolysis at 800 °C allows for catalytic hydrogenations at low temperature of a variety of unsaturated compounds such as quinolines, alkynes, ketones, imines, and polycyclic aromatic hydrocarbons as well as nitroarenes with good activity and selectivity.
N-graphitic-modified cobalt nanoparticles (Co/[email protected]2-800) are shown to be active in the semihydrogenation of alkynes to alkenes. Key to success for efficient catalysis is both the modification of the metal nanoparticles by nitrogen-doped graphitic layers and the use of silica as support. Several internal alkynes are converted to the Z isomer in high yields with up to 93% selectivity. In addition, a
the selective synthesis of (E)-alkenes via the reductive cross-coupling of alkynes and aryl halides using a bimetallic catalyst system composed of a group 4 metallocene difluoride (Cp2[M]F2; [M] = Hf or Zr; Cp = cyclopentadienide) and palladium dichloride. This reaction proceeds via a coupling between an aryl halide and an in situgenerated alkenyl metallocene intermediate derived from the group 4 metallocene
Heck Couplings at Room Temperature in Nanometer Aqueous Micelles
作者:Bruce H. Lipshutz、Benjamin R. Taft
DOI:10.1021/ol702755g
日期:2008.4.1
or the vitamin E-based PTS, both of which form nanomicelles in water, promotes Heck cross-couplings of non-water-soluble partners at ambient temperatures. These are the first examples of Heck reactions conducted in water (as the only solvent) at roomtemperature.