872-31-1Relevant articles and documents
Orthogonal Stability and Reactivity of Aryl Germanes Enables Rapid and Selective (Multi)Halogenations
Deckers, Kristina,Fricke, Christoph,Schoenebeck, Franziska
supporting information, p. 18717 - 18722 (2020/08/25)
While halogenation is of key importance in synthesis and radioimaging, the currently available repertoire is largely designed to introduce a single halogen per molecule. This report makes the selective introduction of several different halogens accessible. Showcased here is the privileged stability of nontoxic aryl germanes under harsh fluorination conditions (that allow selective fluorination in their presence), while displaying superior reactivity and functional-group tolerance in electrophilic iodinations and brominations, outcompeting silanes or boronic esters under rapid and additive-free conditions. Mechanistic experiments and computational studies suggest a concerted electrophilic aromatic substitution as the underlying mechanism.
Multimetallic Ni- and Pd-Catalyzed Cross-Electrophile Coupling to Form Highly Substituted 1,3-Dienes
Olivares, Astrid M.,Weix, Daniel J.
supporting information, p. 2446 - 2449 (2018/02/28)
The synthesis of highly substituted 1,3-dienes from the coupling of vinyl bromides with vinyl triflates is reported for the first time. The coupling is catalyzed by a combination of (5,5′-bis(trifluoromethyl)-2,2′-bipyridine)NiBr2 and (1,3-bis(diphenylphosphino)propane)PdCl2 in the presence of a zinc reductant. This method affords tetra- and penta-substituted 1,3-dienes that would otherwise be difficult to access and tolerates electron-rich and -poor substituents, heterocycles, an aryl bromide, and a pinacol boronate ester. Mechanistically, the reaction appears to proceed by an unusual zinc-mediated transfer of a vinyl group between the nickel and palladium centers.
Sterics vs electronics: Revisiting the catalytic regioselective hydrodebromination of 2,3,5-tribromothiophene
Konkol, Kristine L.,Rasmussen, Seth C.
supporting information, p. 3234 - 3239 (2016/10/09)
The application of sterically hindered palladium catalysts to the regioselective hydrodebromination of 2,3,5-tribromothiophene has been studied in detail, including the effects of catalyst choice, solvent, reaction time, and temperature, as well as the method of NaBH4 addition and the role of chelating additives to effect NaBH4 solubility. Ultimately it was determined that the background reaction between NaBH4 and bromothiophenes is too facile to allow both total conversion and high selectivity. Optimized conditions finally allowed a selectivity of ca. 16:1 with overall conversion of 100%. However, complications of overdebromination under these conditions still limit the yield of the desired 2,3-dibromothiophene to 65%.
Synthesis of poly(thiophene-alt-pyrrole) from a difunctionalized thienylpyrrole by Kumada polycondensation
He, Lu-Ying,Urrego-Riveros, Sara,Gates, Paul J.,N?ther, Christian,Brinkmann, Maren,Abetz, Volker,Staubitz, Anne
supporting information, p. 5399 - 5406 (2015/07/15)
A difunctional thienylpyrrole monomer with a bromide on the thienyl moiety and a magnesium halide on the pyrrole moiety was prepared via chemo-selective magnesium-iodine exchange. Based on this monomer, a π-conjugated alternating poly(thiophene-alt-pyrrole) PTP was synthesized via nickel and palladium catalyzed Kumada polycondensation. The optical and thermal properties of this polymer have been investigated and suggested a wide band gap polymer, with a very low Tg for such polymers.
Enatioselective Chalcogeno-Baylis-Hillman reaction of arylaldehydes with MVK and acrylates catalyzed by chiral thiepin-TiCl4 complex
Yin, Yan,Sun, Guofeng,Zhang, Heng,Zhou, Hong,Wu, Fanhong
, p. 365 - 369 (2014/05/20)
In a rational chiral molecular design of chalcogenides, optically active thiepin with C2-symmetric chirality was synthesized from commercially available thiophene. Then enatioselective Chalcogeno-Baylis-Hillman reactions of arylaldehydes with methyl vinyl ketone (MVK) and acrylates were investigated in the presence of thiepin-Lewis acid complex. Finally, up to 64% ee was achieved in the presence of 0.2 equiv. of (S)-thiepin at 20°C. Enatioselective Chalcogeno-Baylis-Hillman reactions between benzaldehydes and acrylates were investigated in the presence of chiral thiepin-Lewis acid complex. Finally, up to 64% ee was achieved in the presence of 0.2 equiv. of (S)-thiepin at 20°C. Copyright
Dual selectivity: Electrophile and nucleophile selective cross-coupling reactions on a single aromatic substrate
Heinrich, Annika C. J.,Thiedemann, Birk,Gates, Paul J.,Staubitz, Anne
supporting information, p. 4666 - 4669 (2013/10/08)
The development of a high yielding, both nucleophile and electrophile selective cross-coupling reaction with aromatic rings is presented. The reaction is general with respect to functional groups. Furthermore, the products still contain a boronic ester and a bromide. These two functional groups allow them to be easy-to-prepare, highly complex starting materials for further reactions, avoiding protecting group transformations.
Design, synthesis, and fungicidal activity of novel analogues of pyrrolnitrin
Wang, Ming-Zhong,Xu, Han,Feng, Qi,Wang, L.I.-Zhong,Wang, S.U.-Hua,Li, Zheng-Ming
experimental part, p. 7912 - 7918 (2010/09/03)
A series of novel analogues of pyrrolnitrin containing a thiophene moiety were designed and synthesized by a facile method, and their structures were characterized by 1H nuclear magnetic resonance (NMR) and high-resolution mass spectrometry. The isomers IV-h and V-h were isolated, and their structures were identified by 2D NMR, including heteronuclear multiple-quantum coherence (HMQC), heteronuclear multiple-bond correlation (HMBC), and nuclear Overhauser effect spectrometry (NOESY) spectra. Their fungicidal activities against five fungi were evaluated, and the results indicated that some of the title compounds showed excellent fungicidal activities in vitro against Alternaria solani, Gibberella zeae, Physalospora piricola, Fusarium omysporum, and Cercospora arachidicola at the dosage of 50 μg mL-1. Some compounds shown moderate activity at low dosage. Compound V-h could be considered as a leading structure for further design of agricultural fungicides.
Silver-catalyzed protodecarboxylation of heteroaromatic carboxylic acids
Lu, Pengfel,Sanchez, Carolina,Cornella, Josep,Larrosa, Igor
supporting information; experimental part, p. 5710 - 5713 (2010/02/28)
[Chemical Equation Presented] A simple and highly efficient protodecarboxylation procedure for a variety of heteroaromatic carboxylic acids catalyzed by Ag2CO3 and AcOH in DMSO is described. This methodology can also perform the selective monoprotodecarboxylation of several aromatic dicarboxylic acids.
Process for isomerization of 2-halothiophene to 3-halothiophene
-
Page/Page column 3; 4, (2008/06/13)
An improved process and catalyst system for the isomerization of halothiophenes. More particularly, an improved process for the isomerization of 2-halothiopehenes to 3-halothiophenes by reacting a 2-halothiophene with a catalyst and in the presence of a base. The addition of a base additive to the acidic zeolite catalyst allows the desired isomerization reaction to take place while suppressing side-reactions that result in the decomposition of thiophene rings. The catalyst lifetime is thus increased and the amount of catalyst needed for the reaction is reduced, lowering cost.
New regiosymmetrical dioxopyrrolo- and dihydropyrrolo-functionalized polythiophenes
Nielsen, Christian B.,Bjornholm, Thomas
, p. 3381 - 3384 (2007/10/03)
(Chemical Equation Presented) We present the synthesis of two N-alkylated poly(dioxopyrrolothiophene)s and two N-alkylated poly(dihydropyrrolothiophene)s with potential application in the field of conducting polymers. The polymers are synthesized from the corresponding 2,5-dibromothiophenes by an Ullmann-type polymerization and a Stille-type polymerization, respectively. The two N-alkylated poly(dihydropyrrolothiophene)s are the first examples of amino-functionalized polythiophenes built from regiosymmetrical thiophene monomers.
