Inhibition of Nitrosation by Steric Hindrance

González‐Mancebo, Samuel; Calle, Emilio; García-Santos, M. Pilar; Casado, Julio

doi:10.1021/jf960371s

Cited by 11 publications

(10 citation statements)

References 16 publications

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“…71 The current observation indicates that with o-substituted N,N-diethylanilines their production is prevalent, which could be due to steric hindrance diminishing the sp 2 character of nitrogen. Indeed, steric hindrance from o-substituents has previously been reported to block nitrosation, 72 and no successful p-nitrosations of osubstituted N,N-dialkylanilines appears to have been reported in the literature.…”

Section: The Journal Of Organic Chemistrymentioning

confidence: 99%

Substituted 9-Diethylaminobenzo[a]phenoxazin-5-ones (Nile Red Analogues): Synthesis and Photophysical Properties

et al. 2020

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Nile Red is a benzo[a]phenoxazone dye containing a diethylamino substituent at the 9-position. In recent years, it has become a popular histological stain for cellular membranes and lipid droplets due to its unrivaled fluorescent properties in lipophilic environments. This makes it an attractive lead for chemical decoration to tweak its attributes and optimize it for more specialized microscopy techniques, e.g., fluorescence lifetime imaging or two-photon excited fluorescence microscopy, to which Nile Red has never been optimized. Herein, we present synthesis approaches to a series of monosubstituted Nile Red derivatives (9-diethylbenzo[a]phenoxazin-5-ones) starting from 1-naphthols or 1,3-naphthalenediols. The solvatochromic responsiveness of these fluorophores is reported with focus on how the substituents affect the absorption and emission spectra, luminosity, fluorescence lifetimes, and two-photon absorptivity. Several of the analogues emerge as strong candidates for reporting the polarity of their local environment. Specifically, the one- and two-photon excited fluorescence of Nile Red turns out to be very responsive to substitution, and the spectroscopic features can be finely tuned by judiciously introducing substituents of distinct electronic character at specific positions. This new toolkit of 9-diethylbenzo[a]phenoxazine-5-ones constitutes a step toward the next generation of optical molecular probes for advancing the understanding of lipid structures and cellular processes.

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Section: The Journal Of Organic Chemistrymentioning

confidence: 99%

Substituted 9-Diethylaminobenzo[a]phenoxazin-5-ones (Nile Red Analogues): Synthesis and Photophysical Properties

et al. 2020

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“…Since for the nitrosation of taurine the orders with respect to [Nitrite] o and [Tau] o were found to be 2 and 1, [17] respectively, the initial reaction rate was (14). The v o,D value was obtained from the intercept, and k exp was obtained from the slope.…”

Section: Application Of Approach 1 To the Nitrosation Reaction Of Taumentioning

confidence: 99%

“…Biologists have mainly been interested in the pathogenic mechanisms in which nitroso compounds are involved [8,9], whereas chemists have been more interested in their mechanisms of formation [10][11][12] and hence in ways to block or inhibit them [13,14]. Nitrosation reactions (Scheme 1) occur through the attack of a nitrosatable substrate (S) by nitrosating species (Y-NO).…”

Section: Introductionmentioning

confidence: 99%

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Interference by Nitrous Acid Decomposition in the Kinetic Study of Nitrosation Reactions

Arenas‐Valgañón

Gómez‐Bombarelli

González‐Pérez

et al. 2014

Int J of Chemical Kinetics

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Under the acidic conditions of the stomach lumen, nitrosation reactions can occur in the human body between nitrite (added to meat because of its antibotulinic properties) and many compounds such as amino acids. From the results obtained, two conclusions can be drawn: (i) In the quantitative study of nitrosation reactions, it is necessary to take into account the competing reaction of HNO 2 decomposition, which in some conditions is the dominant reaction; (ii) two alternative approaches based on the initial rate method are necessary to assess the weight of nitrous acid decomposition using taurine and homotaurine as nitrosatable substrates. In strongly acidic media, the decomposition reaction is dominant: In the case of taurine, the decomposition rate is negligible at pH ≥ 3.2. In the pH 3.2−2.5 range, decomposition is lower than nitrosation but not negligible, and at pH ≤ 2.5 decomposition is faster than nitrosation. With homotaurine, HNO 2 decomposition is negligible at pH higher than 4.1. In the pH 4.1−2.8 range, nitrosation is faster but decomposition should be considered, and at pH ≤ 2.8 decomposition is the dominant reaction. C

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“…Biologists are mainly interested in the use of these compounds as models for producing a broad range of cancers 2-9 whereas chemists are more interested first in the mechanisms of formation of nitroso compounds 10- 15 and then in blocking or inhibiting such mechanisms of these species. [16][17][18] N-Nitrosation chemistry has been a fruitful area for the mechanistic organic and physical organic chemist. Many reactions are now well understood, and in several cases the nature of the effective nitrosating species has been established, often by kinetic procedures.…”

Section: Introductionmentioning

confidence: 99%

Aromatic C-nitrosation of a bioactive molecule. Nitrosation of minoxidil

et al. 2011

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Minoxidil (2,4-diamino-6-(piperidin-1'-yl)pyrimidine N(3)-oxide; CASRN 38304-91-5) is a bioactive molecule with several nitrosatable groups widely used as an antihypertensive and antialopecia agent. Here the nitrosation of minoxidil was investigated. The conclusions drawn are as follows: (i) In the pH = 2.3-5.0 range, the minoxidil molecule undergoes aromatic C-nitrosation by nitrite. The dominant reaction was C-5 nitrosation through a mechanism that appears to consist of an electrophilic attack on the nitrosatable substrate by H(2)NO(2)(+)/NO(+), followed by a slow proton transfer; (ii) the reactivity of minoxidil as a C-nitrosatable substrate proved to be 7-fold greater than that of phenol, this being attributed to the preferred para- and ortho-orientations of the two -NH(2) groups at positions 2 and 4 of the minoxidil molecule, which activate electrophilic substitution in the C-5 position through their mesomeric effect. The N-nitrosominoxidil resulting from the nitrosation could be potentially harmful to the minoxidil users.

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Inhibition of Nitrosation by Steric Hindrance

Cited by 11 publications

References 16 publications

Substituted 9-Diethylaminobenzo[a]phenoxazin-5-ones (Nile Red Analogues): Synthesis and Photophysical Properties

Substituted 9-Diethylaminobenzo[a]phenoxazin-5-ones (Nile Red Analogues): Synthesis and Photophysical Properties

Interference by Nitrous Acid Decomposition in the Kinetic Study of Nitrosation Reactions

Aromatic C-nitrosation of a bioactive molecule. Nitrosation of minoxidil

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