79449-08-4Relevant articles and documents
Use of "homeopathic" ligand-free palladium as catalyst for aryl-aryl coupling reactions
Alimardanov, Asaf,Schmieder-Van De Vondervoort, Lizette,De Vries, Andre H. M.,De Vries, Johannes G.
, p. 1812 - 1817 (2004)
We have previously shown that the use of ligand-free palladium employing Pd(OAc)2 as catalyst precursor in the Heck reaction of aryl bromides is possible if low catalyst loadings, typically between 0.01-0.1 mol % are used. We have now tested this phenomenon, which we have dubbed " homeopathic" palladium, in biaryl formation using the Suzuki, the Negishi and the Kumada cross-coupling reactions. The Suzuki reaction of aryl bromides, both activated and deactivated, is possible using 0.02-0.05 mol % of Pd(OAc)2. In this reaction turnover frequencies up to 30,000 have been reached with activated substrates. Even aryl chlorides could be reacted if strongly electron-withdrawing substituents were present. The Negishi coupling with a variety of arylzinc halides was possible on aryl bromides containing electron-withdrawing substituents. The Kumada reaction only gave low yields of products under "homeopathic' conditions.
Selective arylation at the vinylic site of cyclic olefins
Wu, Xiaojin,Zhou, Jianrong
supporting information, p. 4794 - 4796 (2013/06/05)
Cyclic olefins usually give Heck products having an aryl ring residing at the allylic or homoallylic position. We describe herein a new method that allows arylation at the vinylic position of various cyclic olefins.
Feeding the Heck reaction with alcohol: One-pot synthesis of stilbenes from aryl alcohols and bromides
Colbon, Paul,Barnard, Jonathan H.,Purdie, Mark,Mulholland, Keith,Kozhevnikov, Ivan,Xiao, Jianliang
supporting information; scheme or table, p. 1395 - 1400 (2012/07/03)
Aryl alcohols are employed as feedstock for the Heck reaction. Keggin-type heteropolyacids catalyse the selective dehydration of the alcohols to styrenes, which, in one-pot, undergo palladium-catalysed Heck arylation with aryl bromides, affording broadly functionalised stilbenes. The choice of solvent is critical for the cascade dehydration-Heck reaction, with electron-rich aryl alcohols preferring a basic medium while electron-deficient ones demanding solvents of lower basicity. Copyright
Response of Acidity and Magnetic Rtesonance Properties to Aryl Substitution in Carbon Acids and Derived Carbanions: 2- and 3-Arylindenes
Greifenstein, Linda G.,Lambert, Joseph B.,Nienhuis, Ronald J.,Fried, Herbert E.,Pagani, Giorgio A.
, p. 5125 - 5132 (2007/10/02)
Substitution in the aryl ring of 2- and 3-arylindenes has been used to examine the acidity of these hydrocarbons and the charge density and ion pair structure of their anions.Acidities were measured for the 2-arylindenes both in pure Me2SO and in Me2SO-H2
