Semi-empirical PM3 treatment of diaryl and dialkyl triazene decomposition in acid media

Rakotondradany, Felaniaina; Williams, Christopher I.; Whitehead, M. A.; Jean-Claude, B.

doi:10.1016/s0166-1280(00)00595-9

Cited by 10 publications

(2 citation statements)

References 12 publications

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“…(1). Instability of triazenes in acidic media precludes measurement of their basicity; however, theoretical calculations have systematically shown that protonation of N3, in spite of being thermodynamically less favorable, is able to compete with that of the (more basic) N1 position 13. That the p K a of TH + (for 1 and 2 ) is much lower than the lowest pH used in this study (i.e., p K a ≪ 6) is fully consistent with the p K a value of 4.95 reported for acid‐promoted decomposition of triazene (HNNNH 2 ) 14, since resonance effects are expected to decrease the electron density, and hence basicity, of the triazeno moiety in diphenyltriazenes relative to that of triazene.…”

Section: Resultsmentioning

confidence: 99%

Inhibition of acid‐induced decomposition of diphenyltriazenes by complexation with cyclodextrins

Asadi

Barra

2010

Int J of Chemical Kinetics

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Acid-promoted N N bond cleavage in 1,3-diphenyltriazenes (X-Ph-N=N-NH-Ph-X; X = H, 4-OCH 3 ), leading to formation of diazonium ions and anilines, is strongly inhibited in aqueous solutions in the presence of cyclodextrins (CDs). The inhibition is ascribed to the formation of inclusion complexes that render the guest diphenyltriazene significantly less basic as a result of the less polar nature of the CD cavity (a microsolvent effect). Association equilibrium constants for 1:1 host-guest complexes increase in the order α-CD <β-CD ∼ permethyl-β-CD < hydroxypropyl-β-CD, with values for X = 4-OCH 3 being larger than those for X = H. In the case of α-CD, formation of 2:1 host-guest complexes is also involved. C

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Section: Resultsmentioning

confidence: 99%

Inhibition of acid‐induced decomposition of diphenyltriazenes by complexation with cyclodextrins

Asadi

Barra

2010

Int J of Chemical Kinetics

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“…[16] Under the latter conditions, these compounds undergo protonation at the N 3 atom followed by scission of the N 2 -N 3 bond to form a secondary amine and a diazonium ion. [17] Indeed, this is a reaction that has been used to release dialkylamines protected as a triazene functionality. [1] However, an investigation by Vaughan and coworkers [18] showed that aryloxymethyltriazenes behaved more like acetals than 3,3-dialkyltriazenes.…”

Section: Introductionmentioning

confidence: 99%

The Mechanism of Hydrolysis of Aryl Ether Derivatives of3‐Hydroxymethyltriazenes

Carvalho¹,

Francisco²,

Iley

et al. 2005

Eur J Org Chem

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1-Aryl-3-aryloxymethyl-3-methyltriazenes hydrolyse to the corresponding anilines and phenols by specific-acid-catalysed, general-acid-catalysed and pH-independent mechanisms. All compounds studied exhibit specific-and general acid catalysis, though for 5a general acid catalysis was not observed below a pH of approximately 4, while for compounds 5e,f, such catalysis was absent above a pH of approximately 5. The pH-independent pathway is observed only for those compounds, 5d-f, that contain good aryloxy nucleofugic groups. The specific-acid-catalysed pathway is supported by a solvent deuterium isotope effect (SDIE) of 0.64, consistent with a mechanism involving protonation of the substrate followed by rate-determining unimolecular decomposition of the protonated species. The k H+ values gave rise to a Hammett ρ value of -0.93, reflecting the competing effect of the substituents on the protonation of the substrate and the cleavage of the aryl ether. Correlation of k H + with the pK a of the phenol leaving group affords a β lg of 0.3. Decomposi-

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Suzuki Coupling of Activated Aryltriazenes for Practical Synthesis of Biaryls from Anilines

2022

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Aryltriazenes can hardly take part in productive organic transformations unless stoichiometric Brönsted or Lewis acid activators are used. We report here for the first time a palladiumcatalyzed Suzuki coupling of aryltriazenes activated by a sulfonyl group at N3 atom under the common basic conditions. Benefiting from elimination of stoichiometric acid activators, activated aryltriazenes could efficiently couple with arylboronic acids to afford diaryls in modest to excellent yields by using a simple catalyst at low loading, 0.3 mol% Pd(PPh 3 ) 2 Cl 2 . Scope and limitation of the coupling are demonstrated with 26 examples.

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Semi-empirical PM3 treatment of diaryl and dialkyl triazene decomposition in acid media

Cited by 10 publications

References 12 publications

Inhibition of acid‐induced decomposition of diphenyltriazenes by complexation with cyclodextrins

Inhibition of acid‐induced decomposition of diphenyltriazenes by complexation with cyclodextrins

The Mechanism of Hydrolysis of Aryl Ether Derivatives of3‐Hydroxymethyltriazenes

Suzuki Coupling of Activated Aryltriazenes for Practical Synthesis of Biaryls from Anilines

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