31125-05-0Relevant articles and documents
Reversible Photoswitchable Inhibitors Generate Ultrasensitivity in Out-of-Equilibrium Enzymatic Reactions
Teders, Michael,Pogodaev, Aleksandr A.,Bojanov, Glenn,Huck, Wilhelm T. S.
supporting information, p. 5709 - 5716 (2021/05/07)
Ultrasensitivity is a ubiquitous emergent property of biochemical reaction networks. The design and construction of synthetic reaction networks exhibiting ultrasensitivity has been challenging, but would greatly expand the potential properties of life-like materials. Herein, we exploit a general and modular strategy to reversibly regulate the activity of enzymes using light and show how ultrasensitivity arises in simple out-of-equilibrium enzymatic systems upon incorporation of reversible photoswitchable inhibitors (PIs). Utilizing a chromophore/warhead strategy, PIs of the protease α-chymotrypsin were synthesized, which led to the discovery of inhibitors with large differences in inhibition constants (Ki) for the different photoisomers. A microfluidic flow setup was used to study enzymatic reactions under out-of-equilibrium conditions by continuous addition and removal of reagents. Upon irradiation of the continuously stirred tank reactor with different light pulse sequences, i.e., varying the pulse duration or frequency of UV and blue light irradiation, reversible switching between photoisomers resulted in ultrasensitive responses in enzymatic activity as well as frequency filtering of input signals. This general and modular strategy enables reversible and tunable control over the kinetic rates of individual enzyme-catalyzed reactions and makes a programmable linkage of enzymes to a wide range of network topologies feasible.
Photochromic Evaluation of 3(5)-Arylazo-1 H-pyrazoles
Rustler, Karin,Nitschke, Philipp,Zahnbrecher, Sophie,Zach, Julia,Crespi, Stefano,K?nig, Burkhard
, p. 4079 - 4088 (2020/04/09)
The desire to photocontrol molecular properties ranging from materials to pharmacology using light as an external trigger with high spatiotemporal resolution led to the development of a broad range of photochromic scaffolds. Among them, azobenzenes are synthetically well accessible and show excellent fatigue resistance. Their photochromic properties vary with the substitution pattern and for different heteroarenes. However, the photochromism of 3(5)-substituted-1H-pryazoles has not yet been investigated, although this compound class offers interesting possibilities of metal ion coordination and hydrogen bond formation via its NH moiety. Herein, we present the results of an experimental and computational investigation of arylazo-3(5)-arylazo-1H-pyrazoles. To elucidate their properties, solvent and substitution effects on their light absorption, thermal half-lives, photostationary states, fatigue, and quantum yields were determined.
Enantioselective Oxidative Coupling of β-Ketocarbonyls and Anilines by Joint Chiral Primary Amine and Selenium Catalysis
Chen, Wanting,Wang, Yanni,Mi, Xueling,Luo, Sanzhong
supporting information, p. 8178 - 8182 (2019/10/16)
An enantioselective primary amine-catalyzed total N-selective nitroso aldol reaction (N-NA) was achieved through the oxidation of primary aromatic amines to the corresponding nitrosoarenes catalyzed by selenium reagents and 30% H2O2. This protocol provides a facile and highly efficient access to α-hydroxyamino carbonyls bearing chiral quaternary centers under exceedingly mild and green reaction conditions with high chemo-and enantiocontrol.
Substrate-Controlled Divergent Synthesis of Enaminones and Pyrroles from Indolizines and Nitroso Compounds
González-Soria, María José,Alonso, Francisco
supporting information, p. 5005 - 5017 (2019/11/03)
It is imperative to learn new synthetic transformations to succeed in drug discovery and development. We report the substrate-driven synthesis of β-enaminones and N-aryl pyrroles from indolizines and nitrosoarenes; aryl-substituted indolizines lead to β-enaminones in a regio- and diastereoselective manner, whereas alkyl-substituted indolizines produce tetrasubstituted pyrroles. All products contain a pyridine unit, the second most abundant ring (after phenyl) in the FDA Orange Book. In both cases, the reactions proceed at room temperature without any catalyst. Moreover, both types of products can be obtained in one pot from commercial materials as well as at a gram scale. It is worthy of note that the regioselectivity of the β-enaminones is inaccessible by the standard literature methods and their utility has been exemplified in the synthesis of diverse heterocycles. We have made every endeavor to put forward the corresponding reaction mechanisms based on thorough experimental work. (Figure presented.).
Anion ligand promoted selective C-F bond reductive elimination enables C(sp2)-H fluorination
Mao, Yang-Jie,Luo, Gen,Hao, Hong-Yan,Xu, Zhen-Yuan,Lou, Shao-Jie,Xu, Dan-Qian
supporting information, p. 14458 - 14461 (2019/12/09)
A detailed mechanism study on the anion ligand promoted selective C-H bond fluorination is reported. The role of the anion ligand has been clarified by experimental evidence and DFT calculations. Moreover, the nitrate promoted C-F bond reductive elimination enabled a selective C-H bond fluorination of various symmetric and asymmetric azobenzenes to access diverse o-fluoroanilines.
Titania-Supported Gold Nanoparticles Catalyze the Selective Oxidation of Amines into Nitroso Compounds in the Presence of Hydrogen Peroxide
Fountoulaki, Stella,Gkizis, Petros L.,Symeonidis, Theodoros S.,Kaminioti, Eleni,Karina, Athanasia,Tamiolakis, Ioannis,Armatas, Gerasimos S.,Lykakis, Ioannis N.
supporting information, p. 1500 - 1508 (2016/05/19)
In this article, the catalytic activity of titania-supported gold nanoparticles (Au/TiO2) was studied for the selective oxidation of amines into nitroso compounds using hydrogen peroxide (H2O2). Gold nanoparticles deposited on Degussa P25 polymorphs of titania (TiO2) have been found to promote the selective formation of a variety of nitroso arenes in high yields and selectivities, even in a large-scale synthesis. In contrast, alkyl amines are oxidized to the corresponding oximes under the examined conditions. Kinetic studies indicated that aryl amines substituted with electron-donating groups are oxidized faster than the corresponding amines bearing an electron-withdrawing functionality. A Hammett-type kinetic analysis of a range of para-X-substituted aryl amines implicates an electron transfer (ET) mechanism (ρ=-1.15) for oxidation reactions with concomitant formation of the corresponding N-aryl hydroxylamine as possible intermediate. We also show that the oxidation protocol of aryl amines in the presence of 1,3-cyclohexadiene leads in excellent yields to the corresponding hetero Diels-Alder adducts between the diene and the in situ formed nitrosoarenes.
An umpolung approach toward N-aryl nitrone construction: A phosphine-mediated addition of 1,2-dicarbonyls to nitroso electrophiles
Chavannavar, Aditi P.,Oliver, Allen G.,Ashfeld, Brandon L.
supporting information, p. 10853 - 10856 (2014/10/16)
An umpolung approach toward nitrone construction utilizing a phosphine-mediated addition of 1,2-dicarbonyls to nitroso compounds is reported. The reaction exhibits a high degree of chemoselectivity and provides direct access to isoxazolidines, imines, and
N-Arylhydroxamic acids as novel oxidoreductase substrates
Kulys, Juozas,Deussen, Heinz-Josef,Krikstopaitis, Kastis,Lolck, Rikke,Schneider, Palle,Ziemys, Arturas
, p. 3475 - 3484 (2007/10/03)
N-Arylhydroxamic acids (AHAs) are promising novel N-OH mediators for oxidoreductase catalysis. They are electrochemically active compounds with a redox potential of 0.31-0.41 V vs. SCE. Representative oxidoreductases, e.g. fungal peroxidase from Coprinus
13C NMR studies of p-substituted nitrosobenzenes
Al-Tahou, Baheeja M.,Gowenlock, Brian G.
, p. 353 - 355 (2007/10/02)
The 13C NMR spectra of a wide range of monomeric para-substituted nitrosobenzenes have been determined end the results related to a wide range of published data for other para-disubstituted benzenes.It is shown that the nitroso substituent exercises a different pattern of effect for the 13C chemical shifts at the ipso C atom from at least twenty eight other substituents.It is noted that when the para substituent is a ?-donor, the nitroso group functions in a different manner from that operative when the para substituent is a ?-acceptor, a general possibility that has already been suggested in the recent literature.
