Palladium catalyzed Suzuki–Miyaura coupling with aryl chlorides using a bulky phenanthryl N-heterocyclic carbene ligand
作者:Chun Song、Yudao Ma、Qiang Chai、Chanqin Ma、Wei Jiang、Merritt B. Andrus
DOI:10.1016/j.tet.2005.05.071
日期:2005.8
carbene (NHC) based palladium acetate catalyst was effective for the coupling of various aryl and vinyl chlorides with organoboron compounds. N,N-Bis-(2,9-dicyclohexyl-10-phenanthryl)-4,5-dihydroimidazolium chloride 8 (H2ICP·HCl) with Pd(OAc)2 and KF·18-c-6 in THF at room temperature gave Suzuki–Miyaura coupling of aryl and vinyl chorides, including unactivated and di-ortho substituted substrates in high
Pd/P(<i>t</i>-Bu)<sub>3</sub>: A Mild and General Catalyst for Stille Reactions of Aryl Chlorides and Aryl Bromides
作者:Adam F. Littke、Lothar Schwarz、Gregory C. Fu
DOI:10.1021/ja020012f
日期:2002.6.1
catalyst for Stille reactions of arylchlorides and bromides, providing solutions to a number of long-standing challenges. An unprecedented array of arylchlorides can be cross-coupled with a range of organotin reagents, including SnBu(4). Very hindered biaryls (e.g., tetra-ortho-substituted) can be synthesized, and arylchlorides can be coupled in the presence of aryl triflates. The method is user-friendly
<i>p</i>-Toluenesulfonic Acid Adsorbed on Silica Gel: An Efficient Dehydrating Agent of Alcohols
作者:Franco D'Onofrio、Arrigo Scettri
DOI:10.1055/s-1985-31463
日期:——
Secondary and tertiary alcohols are efficiently dehydrated by reaction with p-toluenesulfonic acid supported on silica gel. In particular, the procedure allows the direct conversion of 3-hydroxy-steroids into Î2-olefins or Î3,5-dienes, without passing through the mesylate or tosylate esters.
The visible-light photoredox/[Co(III)] cocatalyzed dehydrogenative functionalization of cyclic and acyclic styrylderivatives with carboxylic acids is documented. The methodology enables the chemo- and regioselective allylic functionalization of styrylcompounds, leading to allylic carboxylates (32 examples) under stoichiometric acceptorless conditions. Intermolecular as well as intramolecular variants
Nickel-catalyzedcross-coupling of Grignardreagents with aryl (poly)fluorides or (poly)chlorides can be achieved efficiently in the presence of a new triarylphosphine ligand bearing a nearby hydroxy group. The high reactivity and the unique chemoselectivity (ArF > ArOTf > ArSR) of the catalysis have been attributed to synergy of nickel and magnesium atoms preorganized on the ligand, as has been surmised