5682-08-6Relevant academic research and scientific papers
Tris-NHC-propagated self-supported polymer-based Pd catalysts for heterogeneous C-H functionalization
Choudhury, Joyanta,Dutta, Tapas Kumar,Mandal, Tanmoy,Mohanty, Sunit
supporting information, p. 10182 - 10185 (2021/10/12)
Three-dimensionally propagated imidazolium-containing mesoporous coordination polymer and organic polymer-based platforms were successfully exploited to develop single-site heterogenized Pd-NHC catalysts for oxidative arene/heteroarene C-H functionalization reactions. The catalysts were efficient in directed arene halogenation, and nondirected arene and heteroarene arylation reactions. High catalytic activity, excellent heterogeneity and recyclability were offered by these systems making them promising candidates in the area of heterogeneous C-H functionalization, where efficient catalysts are still scarce.
Diverse Reactions of Thiophenes, Selenophenes, and Tellurophenes with Strongly Oxidizing I(III) PhI(L)2 Reagents
Egalahewa, Sathsara,Albayer, Mohammad,Aprile, Antonino,Dutton, Jason L.
supporting information, p. 1282 - 1288 (2017/02/15)
We report the outcomes of the reactions of aromatic group 16 thiophene, selenophene, and tellurophene rings with the I(III) oxidants PhI(OAc)(OTf) and [PhI(Pyr)2][OTf]2 (Pyr = pyridine). In all reactions, oxidative processes take place, with generation of PhI as the reduction product. However, with the exception of tellurophene with PhI(OAc)(OTf), +4 oxidation state complexes are not observed, but rather a variety of other processes occur. In general, where a C-H unit is available on the 5-membered ring, an electrophilic aromatic substitution reaction of either ?IPh or pyridine onto the ring occurs. When all positions are blocked, reactions with PhI(OAc)(OTf) give acetic and triflic anhydride as the identifiable oxidative byproducts, while [PhI(Pyr)2][OTf]2 gives pyridine electrophilic aromatic substitution onto the peripheral rings. Qualitative mechanistic studies indicate that the presence of the oxidizable heteroatom is required for pyridine to act as an electrophile in a substantial manner.
Pd/C as a catalyst for completely regioselective c=h functionalization of thiophenes under mild conditions
Tang, Dan-Tam D.,Collins, Karl D.,Ernst, Johannes B.,Glorius, Frank
supporting information, p. 1809 - 1813 (2014/03/21)
The completely C3-selective arylation of thiophenes and benzo[b]thiophenes was achieved by using Pd/C as a heterogeneous catalyst without ligands or additives under mild reaction conditions. The practicability of this transformation is demonstrated by notable functional group tolerance and the insensitivity of the reaction to H2O and air. This method is also applicable to nitrogen- and oxygen-containing heterocycles, yielding the corresponding C2-arylated products. Three-phase tests along with Hg-poisoning and hot-filtration tests suggest that the catalytically active species is heterogeneous in nature. I+ can do better! Pd/C can be used without ligands or additives to catalyze the completely C3-selective arylation of diversely substituted thiophenes and benzo[b]thiophenes under mild reaction conditions. The physical nature of the catalytic species was investigated and the mechanism was studied. Relative rate data generated in a "robustness screen" were used to design a complex substrate that undergoes highly chemoselective sequential functionalization. Copyright
Pd-catalyzed β-selective direct C-H bond arylation of thiophenes with aryltrimethylsilanes
Funaki, Kenji,Sato, Tetsuo,Oi, Shuichi
supporting information, p. 6186 - 6189 (2013/02/23)
Direct arylation of thiophenes and benzothiophenes with aryltrimethylsilanes was effectively catalyzed by PdCl2(MeCN) 2 in the presence of CuCl2 as an oxidant. The reaction preferentially occurred at the β-position of both
Thiophenes as Traps for Benzyne. 2. Cycloadditions and Ene Reactions
Reinecke, Manfred G.,Mazza, Dario Del
, p. 2142 - 2146 (2007/10/02)
The reactions of 11 mono- and disubstituted thiophenes (1b-1l) with benzyne generated from diphenyliodonium 2-carboxylate (7) were studied under a standard set of conditions.The major products were naphthalenes (3) whose substitution patterns indicated that both and cycloaddition occurred, with the former predominating.A significant proportion of cycloaddition was found only with the 3-halothiophenes 1i and 1k, suggesting enamine-like enhancement of the 2?-character of the thiophene.Benzothiophenes (8) were found in low yields in several of the reactions, and their substitution patterns suggested a cycloaddition mechanism involving an intermediate betaine 11.Ene (17) and especially double ene (18) products were observed with the alkylthiophenes 1b-d and 1g.The halothiophenes 1h-l underwent substantial carbon-halogen bond cleavage leading to halogenated phenylthiophenes.
