388-82-9Relevant academic research and scientific papers
Catalyst-Free Synthesis of O-Heteroacenes by Ladderization of Fluorinated Oligophenylenes
Feofanov, Mikhail,Akhmetov, Vladimir,Takayama, Ryo,Amsharov, Konstantin
supporting information, p. 5199 - 5203 (2021/02/21)
A novel catalyst-free approach to benzoannulated oxygen-containing heterocycles from fluorinated oligophenylenes is reported. Unlike existing methods, the presented reaction does not require an oxygen-containing precursor and relies on an external oxygen source, potassium tert-butoxide, which serves as an O2? synthon. The radical nature of the reaction facilitates nucleophilic substitution even in the presence of strong electron-donating groups and enables de-tert-butylation required for the complete annulation. Also demonstrated is the applicability of the method to introduce five-, six-, and seven-membered rings containing oxygen, whereas multiple annulations also open up a short synthetic path to ladder-type O-heteroacenes and oligodibenzofurans.
Zirconium-redox-shuttled cross-electrophile coupling of aromatic and heteroaromatic halides
Fu, Yue,Liu, Fang-Jie,Liu, Peng,Tang, Jian-Tao,Toste, F. Dean,Wu, Ting-Feng,Ye, Baihua,Zhang, Yue-Jiao
supporting information, p. 1963 - 1974 (2021/07/07)
Transition metal-catalyzed cross-electrophile coupling (XEC) is a powerful tool for forging C(sp2)–C(sp2) bonds in biaryl molecules from abundant aromatic halides. While the synthesis of unsymmetrical biaryl compounds through multimetallic XEC is of high synthetic value, the selective XEC of two heteroaromatic halides remains elusive and challenging. Herein, we report a homogeneous XEC method, which relies on a zirconaaziridine complex as a shuttle for dual palladium-catalyzed processes. The zirconaaziridine-mediated palladium (ZAPd)-catalyzed reaction shows excellent compatibility with various functional groups and diverse heteroaromatic scaffolds. In accord with density functional theory (DFT) calculations, a redox transmetallation between the oxidative addition product and the zirconaaziridine is proposed as the crucial elementary step. Thus, cross-coupling selectivity using a single transition metal catalyst is controlled by the relative rate of oxidative addition of Pd(0) into the aromatic halide. Overall, the concept of a combined reducing and transmetallating agent offers opportunities for the development of transition metal reductive coupling catalysis.
Synthesis of biaryl compounds via Suzuki homocoupling reactions catalyzed by metal organic frameworks encapsulated with palladium nanoparticles
Bao, Yan-Sai,Cui, Xin-Yu,Han, Zheng-Bo,Li, Xin,Tang, Hong,Yang, Ming,Zhang, Yu-Yang,Zhao, Kun,Zhou, Mei-Li
, (2020/12/17)
Heterogeneous homocoupling reactions of phenylboronic acids were greatly accelerated via Suzuki homocoupling reactions. In this work, a tandem route was designed which firstly one part of phenylboronic acids reacted with iodine to form iodobenzenes, then another part of phenylboronic acids coupled with iodobenzenes to produce biaryl compounds. The tandem reaction were catalyzed by a bifunctional heterogeneous catalyst of metal organic frameworks encapsulated with palladium nanoparticles (Pd?MOFs). This strategy for forming symmetric C-C bond between benzene rings has obvious advantages such as high efficiency, easy separation, good recyclability and no addition of toxic halogenated benzene.
Alumina-promoted oxodefluorination
Amsharov, Konstantin,Mikhail, Feofanov,Vladimir, Akhmetov
, p. 10879 - 10882 (2020/03/27)
A simple protocol for the clean preparation of heterocyclic compounds containing dibenzofuran's core via oxodefluorination of fluoroarenes on activated γ-Al2O3 is reported. Alumina can be considered as a reliable oxygen source enabling one-pot substitution of fluorine atoms and yielding benzoannulated furan derivatives. The corresponding C-F bond activation is selective towards less stable C-Br/C-I and occurs under metal- A nd solvent-free conditions.
Palladium/Sensory Component-Catalyzed Homocoupling Reactions of Aryl Halides
Bai, Haixin,Bao, Fengyu,Chai, Guobi,Liu, Pengfei,Liu, Zhikai,Zhang, Haiyan,Zhang, Qidong
supporting information, (2020/09/09)
A novel and efficient catalyst system was developed for homocoupling reactions of aryl halides. The catalyst system consists of Pd(OAc) 2and the peppery sensory component of tobacco leaves. This is the first time that a sensory component has been used in an organic reaction. Experiments using the catalyst system showed that the reactions proceeded smoothly under air in the absence of both an additional ligand and a reductant. Furthermore, the catalyst system can be applied to the coupling reactions of hetaryl iodides. Many functional groups (including a hydroxy group) are tolerated.
Glucopyranoside-substituted imidazolium-based chiral ionic liquids for Pd-catalyzed homo-coupling of arylboronic acids in water
Huang, Zhiqiang,Kong, Lingfang,Li, Jing,Wu, Yue,Xue, Jun,Yuan, Yangyang,Zhou, Zhonggao
, p. 1 - 12 (2020/07/21)
Chiral ionic liquids (CILs) are widely used solvents and materials with prominent properties. Carbohydrate-derived imidazolium-based CILs represent a distinctive type of CILs possessing multiple chiral centers from natural chiral pool. Herein, a series of glucopyranoside-substituted imidazolium-based CILs (Glu-imi-CILs) were synthesized and evaluated as ligands for Pd-catalyzed homo-coupling reactions of arylboronic acids in water. The glucopyranoside substituent was instrumental for improving the catalytic activity of the resulting catalysts. Moreover, a Glu-imi-CIL with a free hydroxyl group for additional coordination was found to be the most efficient ligand. A series of symmetric biaryl compounds (13 examples) were synthesized from arylboronic acids by this method in high isolated yields (85?99percent).
Efficient Pd-catalyzed oxidative homocoupling of arylboronic acids in aqueous NaClO
Li, Min-Xin,Tang, Yan-Ling,Gao, Hui,Mao, Ze-Wei
supporting information, (2020/03/04)
An efficient, mild and practical method was developed for the synthesis of biaryls via the Pd-catalyzed oxidative homocoupling of aromatic/heteroaromatic boronic acids in aqueous NaClO.
Palladium-mediated radical homocoupling reactions: A surface catalytic insight
Favier, Isabelle,Toro, Marie-Lou,Lecante, Pierre,Pla, Daniel,Gómez, Montserrat
, p. 4766 - 4773 (2018/09/29)
In this contribution, we report a palladium nanoparticle-promoted reductive homocoupling of haloarenes that proceeds efficiently to produce corresponding bis-aryls in moderate to excellent yields using relatively low catalyst loading (1 mol%), and exhibits broad functional group tolerance. This work sheds light on how the surface state of Pd(0) nanoparticles plays a crucial role in the reactivity of catalytic systems. Notably, the appropriate choice of palladium salts for the preparation of the preformed nanocatalysts was a key parameter having a major impact on the catalytic activity; thus, the effect of halide anions on the reactivity of the as-prepared palladium nanoparticles could be assessed, with iodide anions being capable of inhibiting the corresponding homocoupling reaction. The homocoupling reaction mechanism has been further studied by means of radical trap and electron paramagnetic resonance (EPR) experiments, revealing that the reaction proceeds via radical intermediates. Taking into account these data, a plausible reaction mechanism based on single-electron transfer processes on the palladium nanoparticle surface is discussed.
The Rolling-Up of Oligophenylenes to Nanographenes by a HF-Zipping Approach
Steiner, Ann-Kristin,Amsharov, Konstantin Y.
supporting information, p. 14732 - 14736 (2017/10/23)
Intramolecular aryl–aryl coupling is the key transformation in the rational synthesis of nanographenes and nanoribbons. In this respect the C?F bond activation was shown to be a versatile alternative enabling the synthesis of several unique carbon-based nanostructures. Herein we describe an unprecedentedly challenging transformation showing that the C?F bond activation by aluminum oxide allows highly effective domino-like C?C bond formation. Despite the flexible nature of oligophenylene-based precursors efficient regioselective zipping to the target nanostructures was achieved. We show that fluorine positions in the precursor structure unambiguously dictate the “running of the zipping-program” which results in rolling-up of linear oligophenylene chains around phenyl moieties yielding target nanographenes. The high efficiency of zipping makes this approach attractive for the synthesis of unsubstituted nanographenes which are difficult to obtain in pure form by other methods.
Pd(OAc)2 catalyzed homocoupling of arenediazonium salts in ionic liquids: Synthesis of symmetrical biaryls
Savanur, Hemantkumar M.,Kalkhambkar, Rajesh G.,Laali, Kenneth K.
, p. 663 - 667 (2016/01/26)
A facile, high yielding, and simple method for the synthesis of a library of symmetrical biaryls by homocoupling of arenediazonium salts is reported, employing catalytic amounts of Pd(OAc)2 and the readily available imidazolium ionic liquids (ILs), without oxidants, ligands, additives, or volatile solvents. Simple product isolation and recycling/reuse of the IL represent additional advantages of this method.
