670-96-2Relevant articles and documents
Nitrene-like Behaviour of Diazoazoles?
Farras, Jaume,Vilarrasa, Jaume
, p. 1127 - 1129 (1986)
Treatment of 4,5-dicyano-2-diazoimidazole, 2-diazoimidazole, amd 3-diazopyrazole with 1,1-dimethoxyethene affords azolo-as-triazines (1c), (3c), and (8c), respectively; the involvement as intermediates of either aziridines (d), arising from a 'nitrene-like reaction' of diazoazoles, or azoalkenes (b) should be questioned at present.
A sustainable approach towards the three-component synthesis of unsubstituted 1H-imidazoles in the water at ambient conditions
Kapale, Suraj S.,Chaudhari, Hemchandra K.,Mali, Suraj N.,Takale, Balaram S.,Pawar, Hitesh
, p. 712 - 716 (2020/05/22)
A green protocol for the synthesis of unsubstituted imidazoles has been demonstrated herein. The reaction is realized using commercially available lipase enzyme, porcine pancreas lipase (PPL) in water. The reaction conditions are selective and mild which helped to tolerate a wide variety of functional groups to give the desired products in good chemical yields. (Figure presented.).
Electron Transfer Photoredox Catalysis: Development of a Photoactivated Reductive Desulfonylation of an Aza-Heteroaromatic Ring
Qiang-Liu,Liu, Yu-Xiu,Song, Hong-Jian,Wang, Qing-Min
supporting information, p. 3110 - 3115 (2020/07/04)
Herein, we report a protocol for desulfonylation of aza-heteroaromatic rings via photoinduced electron transfer and hydrogen atom transfer. This general protocol has a wide substrate range and moderate to good yields. The utility of the method was demonstrated by the chemoselective desulfonylation of a molecule containing both an aliphatic and an aromatic sulfonamide. (Figure presented.).
Rh/TiO2-Photocatalyzed Acceptorless Dehydrogenation of N-Heterocycles upon Visible-Light Illumination
Bahnemann, Detlef W.,Balayeva, Narmina O.,Dillert, Ralf,Mamiyev, Zamin,Zheng, Nan
, p. 5542 - 5553 (2020/08/25)
TiO2 is an effective and extensively employed photocatalyst, but its practical use in visible-light-mediated organic synthesis is mainly hindered by its wide band gap energy. Herein, we have discovered that Rh-photodeposited TiO2 nanoparticles selectively dehydrogenate N-heterocyclic amines with the concomitant generation of molecular hydrogen gas in an inert atmosphere under visible light (λmax = 453 nm) illumination at room temperature. Initially, a visible-light-sensitive surface complex is formed between the N-heterocycle and TiO2. The acceptorless dehydrogenation of N-heterocycles is initiated by direct electron transfer from the HOMO energy level of the amine via the conduction band of TiO2 to the Rh nanoparticle. The reaction condition was optimized by examining different photodeposited noble metals on the surface of TiO2 and solvents, finding that Rh0 is the most efficient cocatalyst, and 2-propanol is the optimal solvent. Structurally diverse N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, indolines, and others bearing electron-deficient as well as electron-rich substituents underwent the dehydrogenation in good to excellent yields. The amount of released hydrogen gas evinces that only the N-heterocyclic amines are oxidized rather than the dispersant. This developed method demonstrates how UV-active TiO2 can be employed in visible-light-induced synthetic dehydrogenation of amines and simultaneous hydrogen storage applications.
Base-promoted annulation of amidoximes with alkynes: Simple access to 2,4-disubstituted imidazoles
Hua, Ruimao,Iqbal, Muhammad Asif,Lu, Le,Mehmood, Hina
, (2020/09/17)
An efficient construction of imidazole ring by a Cs2CO3-promoied annulation of amidoximes with terminal alkynes in DMSO has been developed. This protocol provides a simple synehetic ropte with high atom-utilieation for the synthesis of 2,4-disubstituted imidazoles in good yields under transition-metal-free and ligand-free conditions. Intornal alkynes can also undetgo the annulation to give 2,4,5-trisubstituted imidazoles.
Deprotection of N-tert-Butoxycarbonyl (Boc) Protected Functionalized Heteroarenes via Addition–Elimination with 3-Methoxypropylamine
Carrick, Jesse D.,Gulledge, Zachary Z.
supporting information, (2020/03/24)
Continued pursuit of functionalized soft-N-donor complexant scaffolds with favorable solubility and kinetics profiles applicable for the separation of the trivalent minor actinides from the lanthanides has attracted significant interest over the last three decades. Recent work from this laboratory resulted in the production of various N-Boc protected [1,2,4]triazinyl-pyridin-2-yl indole Lewis basic procomplexants which necessitated the removal of the indole N-Boc protecting group prior to evaluation of complexant efficacy in separations assays. Traditional deprotection strategies involving trifluoroacetic and other protic and Lewis acids proved unsuccessful in removal of the recalcitrant indole-N-Boc protecting group necessitating the development of a new strategy for deprotection of this complexant class. A serendipitous result facilitated utilization of 3-methoxypropylamine as a mild deprotecting agent for various N-Boc protected heteroarenes via a proposed addition–elimination mechanism. Method development, application to various heteroarenes including indoles, 1,2-indazoles, 1,2-pyrazoles, and related derivatives, a ten-fold scale-up reaction, and experimental evaluation of a preliminary mechanistic hypothesis are reported herein.
Imidazole diarylethene switches: An alternative to acid-gated photochromism
Jiang, Yue,Li, Meng-Lian,Xiong, Kang-Tai,Xu, Hai-Bing,Zeng, Ming-Hua
supporting information, p. 8061 - 8067 (2020/06/10)
We prepared five diarylethenes containing 2-aryl-imidazole as the ethene bridge (L1-L5), and introduced response sites in imidazole rather than in the traditional appended aryl units to regulate their photochromism and thermal stability under acid stimulus. The results show that we can change the thermal stability from P- to T-type, and prevent their photoactivity by acidification, and it is clarified that the stronger the acid or the more acid added, the faster the decay rate of the diarylethene photostability. Furthermore, the prohibited photoactivity could be restored by neutralization with an equimolar amount of base.
Visible-Light-Mediated Photocatalytic Aerobic Dehydrogenation of N-heterocycles by Surface-Grafted TiO2 and 4-amino-TEMPO
Balayeva, Narmina O.,Zheng, Nan,Dillert, Ralf,Bahnemann, Detlef W.
, p. 10694 - 10704 (2019/11/14)
Herein, the visible-light-induced dehydrogenation of N-heterocycles such as tetrahydroquinolines, tetrahydroisoquinolines, and indolines in O2-containing suspensions of a commercially available titanium dioxide photocatalyst yielding the corresponding heteroarenes is presented. 4-Amino-2,2,6,6-tetramethylpipiridinyloxyl (4-amino-TEMPO) was found to exhibit a beneficial role, as it increased the yield and improved the selectivity of the dehydrogenation reaction. Both the selectivity and the yield are further enhanced by grafting 0.1 wt % of Ni(II) ions onto the TiO2 surface. It is proposed that the basic reactant adsorbs at Lewis acid sites present at the TiO2 surface. The dehydrogenation reaction is initiated by visible-light excitation of the resulting surface complex and a subsequent single-electron transfer from the excited N-heterocycle via the conduction band of TiO2 to O2. Ni(II) ions possibly serve as an electron transfer bridge between the conduction band of TiO2 and O2, while the TEMPO derivative is assumed to act as a selective redox mediator involved in reactions of the generated reactive oxygen species.
Palladium catalyzed hydrodefluorination of fluoro-(hetero)arenes
Gair, Joseph J.,Grey, Ronald L.,Giroux, Simon,Brodney, Michael A.
supporting information, p. 2482 - 2487 (2019/04/10)
Palladium catalyzed hydrodefluorination was developed for fine-tuning the properties of fluoro-(hetero)aromatic compounds. The robust reaction can be set up in air, requires only commercially available components, and tolerates a variety of heterocycles and functionalities relevant to drug discovery. Given the prevalence of fluorine incorporation around metabolic hotspots, the corresponding deuterodefluorination reaction may prove useful for converting fluorinated libraries to deuterated analogues to suppress the oxidative metabolism by kinetic isotope effects.
An Angle on MK2 Inhibition—Optimization and Evaluation of Prevention of Activation Inhibitors
Hedstr?m, Ulf,Norberg, Monica,Evertsson, Emma,Lever, Sarah R.,Munck af Rosensch?ld, Magnus,L?nn, Hans,Bold, Peter,K?ck, Helena,Berntsson, Pia,Vinblad, Johanna,Liu, Jianming,Welinder, Anette,Karlsson, Johan,Snijder, Arjan,Pardali, Katerina,Andersson, Ulf,Davis, Andrew M.,Mogemark, Mickael
supporting information, p. 1701 - 1709 (2019/08/21)
The mitogen-activated protein kinase p38α pathway has been an attractive target for the treatment of inflammatory conditions such as rheumatoid arthritis. While a number of p38α inhibitors have been taken to the clinic, they have been limited by their efficacy and toxicological profile. A lead identification program was initiated to selectively target prevention of activation (PoA) of mitogen-activated protein kinase-activated protein kinase 2 (MK2) rather than mitogen- and stress-activated protein kinase 1 (MSK1), both immediate downstream substrates of p38α, to improve the efficacy/safety profile over direct p38α inhibition. Starting with a series of pyrazole amide PoA MK2 inhibitor leads, and guided by structural chemistry and rational design, a highly selective imidazole 9 (2-(3′-(2-amino-2-oxoethyl)-[1,1′-biphenyl]-3-yl)-N-(5-(N,N-dimethylsulfamoyl)-2-methylphenyl)-1-propyl-1H-imidazole-5-carboxamide) and the orally bioavailable imidazole 18 (3-methyl-N-(2-methyl-5-sulfamoylphenyl)-2-(o-tolyl)imidazole-4-carboxamide) were discovered. The PoA concept was further evaluated by protein immunoblotting, which showed that the optimized PoA MK2 compounds, despite their biochemical selectivity against MSK1 phosphorylation, behaved similarly to p38 inhibitors in cellular signaling. This study highlights the importance of selective tool compounds in untangling complex signaling pathways, and although 9 and 18 were not differentiated from p38α inhibitors in a cellular context, they are still useful tools for further research directed to understand the role of MK2 in the p38α signaling pathway.
