16285-97-5Relevant academic research and scientific papers
Enhanced reactivity of twisted amides inside a molecular cage
Takezawa, Hiroki,Shitozawa, Kosuke,Fujita, Makoto
, p. 574 - 578 (2020)
When an amide group is distorted from its planar conformation, the conjugation between the nitrogen lone pair and the π* orbital of the carbonyl is disrupted and the reactivity towards nucleophiles is enhanced. Although there are several reports on the synthesis of activated twisted amides, amide activation through mechanical twisting is much less common. Here, we report twisted amides that are stabilized through their inclusion in a self-assembled coordination cage. When secondary aromatic amides are included in a Td-symmetric cage, the cis-twisted conformation is favoured over the trans-planar one—as evidenced by single-crystal X-ray diffraction analysis—revealing that the amide can twist by up to 34°. As a consequence of this distortion, the hydrolysis of amides is significantly accelerated upon inclusion. [Figure not available: see fulltext.]
A rapid response near-infrared ratiometric fluorescent probe for the real-time tracking of peroxynitrite for pathological diagnosis and therapeutic assessment in a rheumatoid arthritis model
Lu, Jiao,Li, Zan,Zheng, Xinrui,Tan, Jiangkun,Ji, Zhongyin,Sun, Zhiwei,You, Jinmao
, p. 9343 - 9350 (2020)
Peroxynitrite (ONOO-) is a potent bio-oxidant involved in many physiological and pathological processes; however, most of the pathological effects associated with ONOO-in vivo are still ambiguous. Herein, we designed and synthesized two near-infrared ratiometric fluorescent probes, Ratio-A and Ratio-B, for the detection and biological evaluation of ONOO-. The recognition unit diene in the probes could be specifically cleaved by ONOO- with a 94-fold enhancement in the ratiometric fluorescence signal. By imaging ONOO- in immune stimulated cells and acute inflammation mice model using Ratio-A, we investigated the fluctuations of ONOO- levels in a rheumatoid arthritis (RA) model of mice. Ratio-A could be applied for the effective imaging of RA and could rapidly evaluate the response of the RA treatment with methotrexate (MTX). Thus, Ratio-A can be considered as a promising tool for pathological diagnosis and the therapeutic assessment of a wide range of diseases including RA.
Unexpected resistance to base-catalyzed hydrolysis of nitrogen pyramidal amides based on the 7-azabicyclic[2.2.1]heptane scaffold
De Velasco, Diego Antonio Ocampo Gutiérrez,Su, Aoze,Zhai, Luhan,Kinoshita, Satowa,Otani, Yuko,Ohwada, Tomohiko
, (2018/09/26)
Non-planar amides are usually transitional structures, that are involved in amide bond rotation and inversion of the nitrogen atom, but some ground-minimum non-planar amides have been reported. Non-planar amides are generally sensitive to water or other n
Salivary aldehyde dehydrogenase: Activity towards aromatic aldehydes and comparison with recombinant ALDH3A1
Giebultowicz, Joanna,Wolinowska, Renata,Sztybor, Anna,Pietrzak, Monika,Wroczynski, Piotr,Wierzchowski, Jacek
body text, p. 2363 - 2372 (2009/12/24)
A series of aromatic aldehydes was examined as substrates for salivary aldehyde dehydrogenase (sALDH) and the recombinant ALDH3A1. Para-substituted benzaldehydes, cinnamic aldehyde and 2-naphthaldehydes were found to be excellent substrates, and kinetic p
Structure-activity analysis of base and enzyme-catalyzed 4-hydroxybenzoyl coenzyme A hydrolysis
Song, Feng,Zhuang, Zhihao,Dunaway-Mariano, Debra
, p. 1 - 10 (2008/09/16)
In this study, the second-order rate constant k2 of base-catalyzed hydrolysis and the values of kcat, Km and kcat/Km of wild-type Pseudomonas sp. CBS3 4-hydroxybenzoyl coenzyme A (4-HBA-CoA) thioesterase-catalyzed hydrolysis of 4-HBA-CoA and its para-substituted analogs were measured. For the base-catalyzed hydrolysis, the plot of log k2 vs the σ value of the para-substituents was linear with a slope (ρ) of 1.5. In the case of the enzyme-catalyzed hydrolysis, the kcat/Km values measured for the para-substituted analogs defined substrate specificity. Asp32 was shown to play a key role in substrate recognition, and in particular, in the discrimination between the targeted substrate and other cellular benzoyl-CoA thioesters.
Competitive endo- and exo-cyclic C-N fission in the hydrolysis of N-aroyl β-lactams
Tsang, Wing Y.,Ahmed, Naveed,Hemming, Karl,Page, Michael I.
, p. 1432 - 1439 (2007/10/03)
The balance between endo- and exo-cyclic C-N fission in the hydrolysis of N-aroyl β-lactams shows that the difference in reactivity between strained β-lactams and their acyclic analogues is minimal. Attack of hydroxide ion occurs preferentially at the exocyclic acyl centre rather than that of the β-lactam during the hydrolysis of N-p-nitrobenzoyl β-lactam. In general, both endo- and exo-cyclic C-N bond fission occurs in the alkaline hydrolysis of N-aroyl β-lactams, the ratio of which varies with the aryl substituent. Hence, the Bronsted β-values differ for the two processes: -0.55 for the ring-opening reaction and -1.54 for the exocyclic C-N bond fission reaction. For the pH-independent and acid-catalysed hydrolysis of N-benzoyl β-lactam, less than 3% of products are derived from exocyclic C-N bond fission.
Dissociation Constants of Weak Organic Acids in Protic Solvents Obtained from Their First Hyperpolarizabilities in Solution
Ray, Paresh Chandra,Das, Puspendu Kumar
, p. 17891 - 17895 (2007/10/03)
The first hyperpolarizabilities (β) of some weak aromatic organic acids have been measured in protic solvents by the hyper-Rayleigh scattering (HRS) technique at low concentrations.The measured hyperpolarizability (βm) varies between the two extreme limits: the hyperpolarizability of the acid form (βHA) at the lower side and that of the basic form (βA-) at the higher side.The degree of dissociation (α) of the acid in a solvent is related to the measured hyperpolarizability, βm, by the following relationship: βm2 = (1 - α)βHA2 + αβA-2.The calculated β's including solvent effects in terms of an Onsager field do not reproduce the experimentally measured hyperpolarizabilities.Other solvent-induced effects like hydrogen bonding and van der Waals interactions seem to influence the first hyperpolarizability and, thus, indirectly the extent of dissociation of these weak acids in these protic solvents.
Hammett Equation and Micellar Effects upon Deacylation
Bartoletti, Antonella,Bartolini, Simona,Germani, Raimondo,Savelli, Gianfranco,Bunton, Clifford A.
, p. 723 - 728 (2007/10/02)
Substituent effects upon second order rate constants of reaction of OH- with phenyl p-substituted benzoates at surface of micelles of cetyltrialkylammonium bromide (alkyl = Me, Et, Pr and Bu) and tetradecylquinuclidinium bromide fit the Hammett equation.Values of ρ increase with increasing bulk of the surfactant head group and are considerably larger than in water, corresponding to decreases in micellar surface polarity.The effects of substitution of the propyl group into the phenyl and benzoyl groups show that substrate orientation at micellar surface plays no significant kinetic role.
Kinetics and mechanism of the basic hydrolysis of indomethacin and related compounds: A reevaluation
Cipiciani,Ebert,Linda,Rubessa,Savelli
, p. 1075 - 1076 (2007/10/02)
The kinetics of the hydrolysis of indomethacin and related compounds were studied in an alkaline medium at 25°. The pseudo-first-order rate constants were evaluated from log absorbance versus time plots in the ultraviolet. These compounds showed a second-order rate constant at low concentrations of hydroxide ion and a first-order rate constant at higher concentrations of hydroxide ion.
