180267-18-9Relevant academic research and scientific papers
A General Method for the Direct α-Arylation of Nitriles with Aryl Chlorides
You, Jingsong,Verkade, John G.
, p. 5051 - 5053 (2003)
The long-standing challenge of developing a general method for the title methodology is met for a broad range of aryl chlorides through the use of bicyclic P(iBuNCH2CH2)3N (1) as a bulky electron-rich ligand for palladium (see scheme, dba = dibenzylideneacetone).
Palladium-catalyzed arylation of sulfones
Mitin,Kashin,Beletskaya
, p. 802 - 812 (2004)
A procedure was developed for monoarylation of sulfones with aryl halides in the presence of palladium complexes. Optimal reaction conditions were found, and the scope of application of the proposed procedure was determined. The arylation occurs only with those sulfones which are relatively strong CH acids; the corresponding monoarylated sulfones are formed in moderate to high yields. The arylation of carbanions derived from the sulfones and some other CH acids requires the presence of an additional equivalent of base. The presence of the latter is also necessary in stoichiometric reactions of carbanions with the palladium complex CF3C6H4Pd(PPh3)2Br; no reaction occurs in the absence of a base. A new mechanism of arylation was proposed, where the key stage is deprotonation of palladium intermediate ArPdL2CHXY which activates the reductive elimination stage.
Role of base in palladium-catalyzed arylation of carbanions
Mitin, Anton V.,Kashin, Alexander N.,Beletskaya, Irina P.
, p. 1085 - 1090 (2004)
The arylation reaction of carbanions, derived from certain sulfones, cyanoacetic ester and malononitrile, with aryl bromides (using the catalytic system of Pd2dba3/3L, L=PPh3, PtBu3) as well as the reaction of the carbanions with one equivalent of 4-CF3C6 H4 Pd(PPh3)2Br has been studied. These reactions proceed smoothly provided that the base stronger than the initial carbanion is present in the reaction mixture. In the absence of the above type of base the reactions do not proceed at all. Taking that into account we have proposed a novel mechanism of palladium-catalyzed arylation of CH-acids. The main feature of this mechanism is the accelaration of the reductive elimination due to the deprotonation of the intermediate ArPdL2CHXY. The correlation between the carbanion reactivity and the pKa values for related CH-acids as well as the ligand effect are discussed in the framework of the proposed mechanism.
Catalyst for aromatic C—O, C—N, and C—C bond formation
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, (2008/06/13)
The present invention is directed to a transition metal catalyst, comprising a Group 8 metal and a ligand having the structure wherein R, R′ and R″ are organic groups having 1-15 carbon atoms, n=1-5, and m=0-4. The present invention is also directed to a method of forming a compound having an aromatic or vinylic carbon-oxygen, carbon-nitrogen, or carbon-carbon bond using the above catalyst. The catalyst and the method of using the catalyst are advantageous in preparation of compounds under mild conditions of approximately room temperature and pressure.
Palladium-catalyzed arylation of malonates and cyanoesters using sterically hindered trialkyl- and ferrocenyldialkylphosphine ligands
Beare, Neil A.,Hartwig, John F.
, p. 541 - 555 (2007/10/03)
Palladium-catalyzed reactions of aryl bromides and chlorides with two common stabilized carbanions - enolates of dialkyl malonates and alkyl cyanoesters - are reported. An exploration of the scope of these reactions was conducted, and the processes were shown to occur in a general fashion. Using P(t-Bu)3 (1), the pentaphenylferrocenyl ligand (Ph5C5)Fe(C5H4)P(t-Bu) 2 (2), or the adamantyl ligand (1-Ad)P(t-Bu)2 (3), reactions of electron-poor and electron-rich, sterically hindered and unhindered aryl bromides and chlorides were shown to react with diethyl malonate, di-tertbutyl malonate, diethyl fluoromalonate, ethyl cyanoacetate, and ethyl phenylcyanoacetate. Although alkyl malonates and ethyl alkylcyanoacetates did not react with aryl halides using these catalysts, the same products were formed conveniently in one pot from diethylmalonate by cross-coupling of an aryl halide in the presence of excess base and subsequent alkylation.
