25027-33-2Relevant academic research and scientific papers
Efficient Pd-Catalyzed Direct Coupling of Aryl Chlorides with Alkyllithium Reagents
Dilchert, Katharina,Gessner, Viktoria H.,Gro?johann, Angela,Rodstein, Ilja,Scherpf, Thorsten,Steinert, Henning,Tappen, Jens
supporting information, p. 20596 - 20603 (2020/09/09)
Organolithium compounds are amongst the most important organometallic reagents and frequently used in difficult metallation reactions. However, their direct use in the formation of C?C bonds is less established. Although remarkable advances in the coupling of aryllithium compounds have been achieved, Csp2?Csp3 coupling reactions are very limited. Herein, we report the first general protocol for the coupling or aryl chlorides with alkyllithium reagents. Palladium catalysts based on ylide-substituted phosphines (YPhos) were found to be excellently suited for this transformation giving high selectivities at room temperature with a variety of aryl chlorides without the need for an additional transmetallation reagent. This is demonstrated in gram-scale synthesis including building blocks for materials chemistry and pharmaceutical industry. Furthermore, the direct coupling of aryllithiums as well as Grignard reagents with aryl chlorides was also easily accomplished at room temperature.
Regioselective differentiation of vicinal methylene C-H bonds enabled by silver-catalysed nitrene transfer
Scamp, Ryan J.,Scheffer, Bradley,Schomaker, Jennifer M.
supporting information, p. 7362 - 7365 (2019/06/27)
Silver-catalyzed nitrene insertion enables the formation of benzosultams in good yield and with regioselectivity complementary to other transition metal nitrene-transfer catalysts. Preferential formation of six-membered benzosultam rings predominates for alkyl-substituted benzenesulphonamide precursors. Ligand-controlled tunability is also achieved for benzenesulphonamides with γ-branched alkyl substituents. Mechanistic probes suggest that the reaction pathway differs depending on whether a α (benzylic) or β (homobenzylic) C-H bond undergoes amidation, as well as the catalyst identity.
Air stable, sterically hindered ferrocenyl dialkylphosphines for palladium-catalyzed C-C, C-N, and C-O bond-forming cross-couplings
Kataoka, Noriyasu,Shelby, Quinetta,Stambuli, James P.,Hartwig, John F.
, p. 5553 - 5566 (2007/10/03)
Pentaphenylferrocenyl di-tert-butylphosphine has been prepared in high yield from a two-step synthetic procedure, and the scope of various cross-coupling processes catalyzed by complexes bearing this ligand has been investigated. This ligand creates a remarkably general palladium catalyst for aryl halide amination and for Suzuki coupling. Turnovers of roughly 1000 were observed for aminations with unactivated aryl bromides or chlorides. In addition, complexes of this ligand catalyzed the formation of selected aryl ethers under mild conditions. The reactions encompassed electron-rich and electron-poor aryl bromides and chlorides. In the presence of catalysts containing this ligand, these aryl halides coupled with acyclic or cyclic secondary alkyl- and arylamines, with primary alkyl- and arylamines, and with aryl- and primary alkylboronic acids. These last couplings provide the first general procedure for reaction of terminal alkylboronic acids with aryl halides without toxic or expensive bases. The ligand not only generates highly active palladium catalysts, but it is air stable in solution and in the solid state. Palladium(0) complexes of this ligand are also air stable as a solid and react only slowly with oxygen in solution.
Perfluorooctanesulfonic acid catalyzed Friedel-Crafts alkylation with alkyl halides
Fu,He,Lei,Luo
, p. 1273 - 1279 (2007/10/02)
A new procedure to prepare superacid perfluorooctanesulfonic acid (POSA) is reported. POSA catalyzed Friedel-Crafts alkylation of aromatic compounds with alkyl halides in liquid-phase reactions. Alkylation gave higher total yields than the corresponding reactions with Nafion-H, without the need of any complex decomposition or work-up. The reactions do not need to be carried out under absolutely anhydrous condition. The catalyst POSA can be easily separated from the reaction mixture and reused or recovered. The reactivity of the alkylation reagents and the mechanism of the reaction are discussed.
