Comparative studies for selective deprotection of the N-arylideneamino moiety from heterocyclic amides: kinetic and theoretical studies. Part 2

Al‐Awadi, Nouria A.; Ibrahim, Yehia A.; Dib, Hicham H.; Ibrahim, Maher R.; George, Boby J.; Abdallah, Mariam R.

doi:10.1016/j.tet.2006.04.054

Cited by 9 publications

(6 citation statements)

References 12 publications

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“…1 H NMR (CDCl 3 ): δ 1.90 (quint, 2H, J = 6.4, CH 2 ), 2.10 (br, 1H, OH), 3.05 (t, 2H, J = 7.0, CH 2 ), 3.78 (t, 2H, J = 6.0, CH 2 ), 7.20 (t, 1H, J = 7.2), 7.30 (t, 2H, J = 7.6), 7.38 (d, 2H, J = 7.8). 13 …”

Section: -mentioning

confidence: 99%

“…The relative ratios of the sample and the internal standard (A) at each reaction temperature was calculated for a minimum of two kinetic runs, made at each of these temperatures that were in agreement within ±2% to ensure reproducible values of A [13,14]. The rate coefficients at T = 600 K were calculated using the kinetic relation log k = log A − E a /2.303 RT, where log A and E a are the Arrhenius parameters obtained for the substrates.…”

Section: Kinetics and Data Analysismentioning

confidence: 99%

“…1 H and 13 C NMR spectra were recorded on a Bruker DPX 400 MHz superconducting NMR spectrometer. Mass spectra were measured on VG Autospec-Q (highresolution, high-performance, tri-sector GC/MS/MS), and with LCMS using Agilent 1100 series LC/MSD with an API-ES/APCI ionization mode.…”

Section: Introductionmentioning

confidence: 99%

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Gas‐phase pyrolytic reaction of 3‐phenoxy and 3‐phenylsulfanyl‐1‐propanol derivatives: Kinetic and mechanistic study

Dib

Ibrahim

Al‐Awadi

et al. 2007

Int J of Chemical Kinetics

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3-Phenoxy-1-propanols 1a-c and 3-phenylsulfanyl-1-propanols 2a-c containing primary, secondary, and tertiary alcohols were prepared and subjected to gas-phase pyrolysis in a static reaction system. Pyrolysis of 4-phenyl-1-butanol 3, 2-methyl-3-phenyl-1-propanol 4, and 2-methyl-3-phenylpropanoic acid 5 was also studied, and results were compared with those obtained for compounds 1-3. The pyrolytic reactions were homogeneous and followed a first-order rate equation. Analysis of the pyrolysate showed the products to be phenol (from 1a to 1c), thiophenol (from 2a to 2c), and toluene (from 3 to 5) and carbonyl compounds. The kinetic results and product analysis of each of the nine investigated compounds are rationalized in terms of a plausible transition state for the elimination pathway. C 2007 Wiley Periodicals, Inc. Int J Chem Kinet 40: [51][52][53][54][55][56][57][58] 2008

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Section: -mentioning

confidence: 99%

Section: Kinetics and Data Analysismentioning

confidence: 99%

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Gas‐phase pyrolytic reaction of 3‐phenoxy and 3‐phenylsulfanyl‐1‐propanol derivatives: Kinetic and mechanistic study

Dib

Ibrahim

Al‐Awadi

et al. 2007

Int J of Chemical Kinetics

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“…6‐azauracil (1,2,4‐triazine‐3,5(2 H ,4 H )‐dione, 6‐AU) was formerly used as an antitumor drug and has been studied extensively. Many experimental and theoretical studies have revealed its structural, chemical, and spectroscopic properties . The crystal structure of 6‐azauracil is reported by Singh and Hodgson .…”

Section: Introductionmentioning

confidence: 99%

A Hybrid statistical mechanics—quantum chemical model for proton transfer in 5‐azauracil and 6‐azauracil in water solution

Маркова

Pejov

Enchev

2015

Int J of Quantum Chemistry

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A hybrid statistical physics—quantum‐chemical methodology was implemented to study the water‐assisted intramolecular proton‐transfer processes in 5‐ and 6‐azauracils in aqueous solutions. The solvent effects were included in the model by explicit inclusion of two pairs of water molecules, which model the relevant part of the first hydration shell around the solute. The position of these water molecules was initially estimated by carrying out a classical Metropolis of dilute water solutions of the title compounds and subsequently analyzing solute–solvent intermolecular interactions in the Monte Carlo‐generated configurations. Sequentially to the statistical physics simulation, ab initio quantum mechanical (QM) level of theory was implemented. The effects of the water as solvent (at ab initio QM level) were introduced at two different levels—using solute–solvent clusters (four‐water molecules) and using the same clusters embedded in an external continuum. Full geometry optimizations of these complexes were carried out at MP2/6–31 + G(d, p) and conductor‐polarizable continuum model (C‐PCM)/MP2/6–31 + G(d, p). Single point calculations were performed at CCSD(T)/6–31 + G(d, p)//MP2/6–31 + G(d, p) computational level to obtain more accurate energies. According to our calculations hydrated azauracils should exist in three forms: mainly dioxo form and two hydroxy forms. The calculated proton transfer activation energies for tautomeric reactions of 5‐azauracil and 6‐azauracil show different pictures for these two compounds. According to C‐PCM/MP2/6–31 +G(d, p) data, water‐assisted proton transfer in 5‐azauracil realizes through two parallel reactions: 1,3,5‐triazine‐2,4(1H,3H)‐dione → 6‐hydroxy‐1,3,5‐triazin‐2(1H)‐one and 1,3,5‐triazine‐2,4(1H,3H)‐dione → 4‐hydroxy‐1,3,5‐triazin‐2(1H)‐one. Tautomeric equilibrium in 6‐azauracil in water could occur by two contiguous reactions: 1,2,4‐triazine‐3,5(2H,4H)‐dione → 5‐hydroxy‐1,2,4‐triazin‐3(2H)‐one and 5‐hydroxy‐1,2,4‐triazin‐3(2H)‐one → 3‐hydroxy‐1,2,4‐triazin‐5(2H)‐one. The proton transfer investigated reactions in 5‐ and 6‐azauracils involve concerted atomic movement. © 2015 Wiley Periodicals, Inc.

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“…N ‐Aminoheteroaromatics are readily obtainable precursors [1–5]. The amino function could then be condensed with aromatic aldehydes into 1 .…”

Section: Introductionmentioning

confidence: 99%

Gas‐phase pyrolysis in organic synthesis: A route for synthesis of cyanamides

Al‐Awadi

Abdelkhalik

El‐Dusouqui

et al. 2009

Journal of Heterocyclic Chem

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in Wiley InterScience (www.interscience.wiley.com).Pyrolysis of 1,7-di-[(E)-1-morpholinomethylidene]-and 1,7-di-[(E)-1-piperidino-methylidene]-4,6,10,12-tetramethylamino-2,8-dioxo-1,7-diaza-3,5,9,11-cyclododecatetraene-3,9-dicarbonitrile 6a,b afforded pyridone 10 in addition to cyanamides 11a,b. On the other hand, pyrolysis of 1-[E-(4-(E-3-cyano-4,6-dimethyl-2-oxopyridin-1(2H)-ylimino) methylpiperazin-1-yl] methylenamino-4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile 8 gave 1-amino-4,6-dimethyl-2-oxo-1,2-dihydropyridine-3-carbonitrile 13 as well as piperazine. The mechanism of pyrolysis and the effect of stereochemistry of pyrolyzed substrates on the nature of the pyrolysates are discussed.

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Comparative studies for selective deprotection of the N-arylideneamino moiety from heterocyclic amides: kinetic and theoretical studies. Part 2

Cited by 9 publications

References 12 publications

Gas‐phase pyrolytic reaction of 3‐phenoxy and 3‐phenylsulfanyl‐1‐propanol derivatives: Kinetic and mechanistic study

Gas‐phase pyrolytic reaction of 3‐phenoxy and 3‐phenylsulfanyl‐1‐propanol derivatives: Kinetic and mechanistic study

A Hybrid statistical mechanics—quantum chemical model for proton transfer in 5‐azauracil and 6‐azauracil in water solution

Gas‐phase pyrolysis in organic synthesis: A route for synthesis of cyanamides

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