611-32-5Relevant academic research and scientific papers
Three-Component Couplings among Heteroarenes, Difluorocyclopropenes, and Water via C-H Activation
Liu, Xuexin,Chen, Jian,Yang, Chunyan,Wu, Zhouping,Li, Zhiyang,Shi, Yuesen,Huang, Tianle,Yang, Zhongzhen,Wu, Yong
supporting information, p. 6831 - 6835 (2021/09/08)
Three-component couplings have been realized for efficiently constructing various nitrogen-containing skeletons via C-H activation, where difluorocyclopropenes have been first identified as coupling partners. Many substrates including sp2 and sp3 C-H substrates were well tolerated, furnishing the corresponding products in good yields. Furthermore, a catalyst-dependent reaction was also developed, enabling divergent construction of two different frameworks. The application value of these reactions was demonstrated in gram-scale experiments with as little as 1 mol % catalyst.
Metal–Organic Layers Hierarchically Integrate Three Synergistic Active Sites for Tandem Catalysis
Quan, Yangjian,Lan, Guangxu,Shi, Wenjie,Xu, Ziwan,Fan, Yingjie,You, Eric,Jiang, Xiaomin,Wang, Cheng,Lin, Wenbin
supporting information, p. 3115 - 3120 (2020/12/09)
We report the design of a bifunctional metal–organic layer (MOL), Hf12-Ru-Co, composed of [Ru(DBB)(bpy)2]2+ [DBB-Ru, DBB=4,4′-di(4-benzoato)-2,2′-bipyridine; bpy=2,2′-bipyridine] connecting ligand as a photosensitizer and Co(dmgH)2(PPA)Cl (PPA-Co, dmgH=dimethylglyoxime; PPA=4-pyridinepropionic acid) on the Hf12 secondary building unit (SBU) as a hydrogen-transfer catalyst. Hf12-Ru-Co efficiently catalyzed acceptorless dehydrogenation of indolines and tetrahydroquinolines to afford indoles and quinolones. We extended this strategy to prepare Hf12-Ru-Co-OTf MOL with a [Ru(DBB)(bpy)2]2+ photosensitizer and Hf12 SBU capped with triflate as strong Lewis acids and PPA-Co as a hydrogen transfer catalyst. With three synergistic active sites, Hf12-Ru-Co-OTf competently catalyzed dehydrogenative tandem transformations of indolines with alkenes or aldehydes to afford 3-alkylindoles and bisindolylmethanes with turnover numbers of up to 500 and 460, respectively, illustrating the potential use of MOLs in constructing novel multifunctional heterogeneous catalysts.
Covalent Organic Frameworks toward Diverse Photocatalytic Aerobic Oxidations
Liu, Shuyang,Tian, Miao,Bu, Xiubin,Tian, Hua,Yang, Xiaobo
supporting information, p. 7738 - 7744 (2021/05/07)
Photoactive two-dimensional covalent organic frameworks (2D-COFs) have become promising heterogenous photocatalysts in visible-light-driven organic transformations. Herein, a visible-light-driven selective aerobic oxidation of various small organic molecules by using 2D-COFs as the photocatalyst was developed. In this protocol, due to the remarkable photocatalytic capability of hydrazone-based 2D-COF-1 on molecular oxygen activation, a wide range of amides, quinolones, heterocyclic compounds, and sulfoxides were obtained with high efficiency and excellent functional group tolerance under very mild reaction conditions. Furthermore, benefiting from the inherent advantage of heterogenous photocatalysis, prominent sustainability and easy photocatalyst recyclability, a drug molecule (modafinil) and an oxidized mustard gas simulant (2-chloroethyl ethyl sulfoxide) were selectively and easily obtained in scale-up reactions. Mechanistic investigations were conducted using radical quenching experiments and in situ ESR spectroscopy, all corroborating the proposed role of 2D-COF-1 in photocatalytic cycle.
Iron(II)-Catalyzed Aerobic Biomimetic Oxidation of N-Heterocycles
Manna, Srimanta,Kong, Wei-Jun,B?ckvall, Jan-E.
supporting information, p. 13725 - 13729 (2021/09/08)
Herein, an iron(II)-catalyzed biomimetic oxidation of N-heterocycles under aerobic conditions is described. The dehydrogenation process, involving several electron-transfer steps, is inspired by oxidations occurring in the respiratory chain. An environmentally friendly and inexpensive iron catalyst together with a hydroquinone/cobalt Schiff base hybrid catalyst as electron-transfer mediator were used for the substrate-selective dehydrogenation reaction of various N-heterocycles. The method shows a broad substrate scope and delivers important heterocycles in good-to-excellent yields.
Highly Ordered Mesoporous Cobalt Oxide as Heterogeneous Catalyst for Aerobic Oxidative Aromatization of N-Heterocycles
Cao, Yue,Wu, Yong,Zhang, Yuanteng,Zhou, Jing,Xiao, Wei,Gu, Dong
, p. 3679 - 3686 (2021/06/18)
N-heterocycles are key structures for many pharmaceutical intermediates. The synthesis of such units normally is conducted under homogeneous catalytic conditions. Among all methods, aerobic oxidative aromatization is one of the most effective. However, in homogeneous conditions, catalysts are difficult to be recycled. Herein, we report a heterogeneous catalytic strategy with a mesoporous cobalt oxide as catalyst. The developed protocol shows a broad applicability for the synthesis of N-heterocycles (32 examples, up to 99 % yield), and the catalyst presents high turnover numbers (7.41) in the absence of any additives. Such a heterogenous approach can be easily scaled up. Furthermore, the catalyst can be recycled by simply filtration and be reused for at least six times without obvious deactivation. Comparative studies reveal that the high surface area of mesoporous cobalt oxide plays an important role on the catalytic reactivity. The outstanding recycling capacity makes the catalyst industrially practical and sustainable for the synthesis of diverse N-heterocycles.
Visible-light-mediated organoboron-catalysed metal-free dehydrogenation of N-heterocycles using molecular oxygen
Wei, Lanfeng,Wei, Yu,Xu, Liang,Zhang, Jinli
supporting information, p. 4446 - 4450 (2021/06/30)
The surge of photocatalytic transformation not only provides unprecedented synthetic methods, but also triggers the enthusiasm for more sustainable photocatalysts. On the other hand, oxygen is an ideal oxidant in terms of atom economy and environmental friendliness. However, the poor reactivity of oxygen at the ground state makes its utilization challenging. Herein, a visible-light-induced oxidative dehydrogenative process is disclosed, which uses an organoboron compound as the photocatalyst and molecular oxygen as the sole oxidant.Viathis approach, an array of N-heterocycles have been accessed under metal-free mild conditions, in good to excellent yields.
Metal-Free Deoxygenation of Amine N-Oxides: Synthetic and Mechanistic Studies
Lecroq, William,Schleinitz, Jules,Billoue, Mallaury,Perfetto, Anna,Gaumont, Annie-Claude,Lalevée, Jacques,Ciofini, Ilaria,Grimaud, Laurence,Lakhdar, Sami
, p. 1237 - 1242 (2021/06/01)
We report herein an unprecedented combination of light and P(III)/P(V) redox cycling for the efficient deoxygenation of aromatic amine N-oxides. Moreover, we discovered that a large variety of aliphatic amine N-oxides can easily be deoxygenated by using only phenylsilane. These practically simple approaches proceed well under metal-free conditions, tolerate many functionalities and are highly chemoselective. Combined experimental and computational studies enabled a deep understanding of factors controlling the reactivity of both aromatic and aliphatic amine N-oxides.
Cobalt-catalyzed ring-opening addition of azabenzonorbornadienes: Via C(sp3)-H bond activation of 8-methylquinoline
Tan, Heng,Khan, Ruhima,Xu, Dandan,Zhou, Yongyun,Zhang, Xuexin,Shi, Guangrui,Fan, Baomin
supporting information, p. 12570 - 12573 (2020/11/02)
The first ring-opening addition of a benzylic C(sp3)-H bond to azabenzonorbornadienes is demonstrated. The reaction proceeded under the catalytic system of [Cp?CoI2(CO)], AgSbF6 and Fe(OAc)2 in PhOMe. The methodology showed a good substrate scope with up to 96 yield. The relative configuration of the product was determined as cis-configuration by X-ray crystallography.
Iodonium Ylides as Carbene Precursors in Rh(III)-Catalyzed C-H Activation
Jiang, Yuqin,Li, Pengfei,Li, Xingwei,Liu, Bingxian,Zhao, Jie
supporting information, p. 7475 - 7479 (2020/10/12)
The rhodium(III)-catalyzed coupling of C-H substrates with iodonium ylides has been realized for the efficient synthesis of diverse cyclic skeletons, where the iodonium ylides have been identified as efficient and outstanding carbene precursors. The reaction systems are applicable to both sp2 and sp3 C-H substrates under mild and redox-neutral conditions. The catalyst loading can be as low as 0.5 mol % in a gram-scale reaction. Representative products exhibit cytotoxicity toward human cancer cells at nanomolar levels.
Iodine-catalyzed convergent aerobic dehydro-aromatization toward benzazoles and benzazines
Chen, Shanping,Deng, Guo-Jun,Jiang, Pingyu,Ni, Penghui,Tuo, Xiaolong,Wang, Xiaodong
, p. 8348 - 8351 (2020/03/11)
An iodine-catalyzed aerobic dehydro-aromatization has been developed, providing straightforward and efficient access to various benzoazoles and benzoazines. The present transition-metal-free protocol enables the dehydro-aromatization of tetrahydrobenzazoles and tetrahydroquinolines with molecular oxygen as the green oxidant, along with some other N-heterocycles. Hence, a broad range of heteroaromatic compounds are generated in moderate to good yields under facile reaction conditions.
