C–H Alkenylation of Heteroarenes: Mechanism, Rate, and Selectivity Changes Enabled by Thioether Ligands
作者:Bradley J. Gorsline、Long Wang、Peng Ren、Brad P. Carrow
DOI:10.1021/jacs.7b03887
日期:2017.7.19
catalytic intermediate in these reactions may also account for unusual catalyst-controlled site selectivity wherein C–H alkenylation of five-atom heteroarenes can occur under electronic control with thioether ligands even when this necessarily involves reaction at a more hindered C–H bond. The thioether effect also enables short reaction times under mild conditions for many O-, S-, and N-heteroarenes (55 examples)
Vinyl tris(trimethylsilyl)silanes: substrates for Hiyama coupling
作者:Zhizhong Wang、Jean-Philippe Pitteloud、Lucresia Montes、Magdalena Rapp、Djenny Derane、Stanislaw F. Wnuk
DOI:10.1016/j.tet.2008.03.024
日期:2008.5
The oxidative treatment of vinyl tris(trimethylsilyl)silanes with hydrogen peroxide in aqueous sodium hydroxide in tetrahydrofuran generates reactive silanol or siloxane species that undergo Pd-catalyzed cross-couplings with aryl, heterocyclic and alkenyl halides in the presence of Pd(PPh(3))(4) and tetrabutylammonium fluoride. Hydrogen peroxide and base are necessary for the coupling to occur while
Aerobic Dehydrogenative Heck Reactions of Heterocycles with Styrenes: A Negative Effect of Metallic Co-Oxidants
作者:Alexandre Vasseur、Dominique Harakat、Jacques Muzart、Jean Le Bras
DOI:10.1002/adsc.201200787
日期:2013.1.14
The aerobicdehydrogenativeHeckreaction (DHR) of heterocycles with styrenes was found to be more efficient in the absence of metallic co‐oxidants. According to a study of the isotope effect, the CH cleavage was the rate‐determining step of the catalytic cycle. Electrospray ionization mass spectrometry, subsequent MS/MS, and high‐resolution mass spectrometry were used to detect and characterize catalytic
Dehydrogenative Heck Reaction of Furans and Thiophenes with Styrenes under Mild Conditions and Influence of the Oxidizing Agent on the Reaction Rate
作者:Alexandre Vasseur、Jacques Muzart、Jean Le Bras
DOI:10.1002/chem.201101992
日期:2011.11.4
CH vs. CBr in Heck: The direct dehydrogenative coupling of furans and thiophenes with styrenes occurs under mild conditions (see scheme). This method allows the coupling of brominated substrates through CH bond activation. In addition, DMSO and benzoquinone had a positive effect on the reaction rate.
Zeolite Y nanosheets with micro-meso-macroporous structure was synthesized, and applied to assemble Pd catalyst (Pd/NS-Y) for direct vinylation of thiophenes in high activity and selectivity, as compared to Pd(OAc)2, Pd(NO3)2,...