scholarly journals Synthesis of New C-3 Substituted Kynurenic Acid Derivatives

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 937 ◽  
Author(s):  
Bálint Lőrinczi ◽  
Antal Csámpai ◽  
Ferenc Fülöp ◽  
István Szatmári
Keyword(s):  
Dft Calculations ◽  
Tertiary Amine ◽  
Mannich Reaction ◽  
Kynurenic Acid ◽  
Side Chains ◽  
Aromatic System ◽  
Spectroscopic Measurements ◽  
Tautomer Form ◽  
Influence Of Substituents

The application of kynurenic acid (KYNA) as an electron-rich aromatic system in the modified Mannich reaction has been examined. The extension possibility of the reaction was tested by using amines occurring in a number of bioactive products, such as morpholine, piperidine, or N-methylpiperazine and aldehydes of markedly different reactivities, like formaldehyde and benzaldehyde. The influence of substituents attached to position 3 on the aminoalkylation was also investigated. Thus, reactions of 3-carbamoyl-substituted precursors with tertiary amine containing side-chains were also tested to afford new KYNA derivatives with two potential cationic centers. By means of NMR spectroscopic measurements, supported by DFT calculations, the dominant tautomer form of KYNA derivatives was also determined.

Influence de la structure du prépolymère sur la température de transition vitreuse de polyuréthanes réticulés

1969 ◽  
Vol 47 (24) ◽  
pp. 4515-4520 ◽  
Author(s):  
Guy Perrault
Keyword(s):  
Glass Transition ◽  
Tertiary Amine ◽  
Polymeric Chain ◽  
Side Chains ◽  
Transition Temperatures ◽  
Glass Transition Temperatures

The influence of prepolymer structure on glass transition temperatures (Tg) of cross-linked polyurethanes has been studied with polysebacates from a homologous family of N-substituted bis(2-hydroxyalkyl)amines. The tertiary amine segments have made it possible to study the effect of lengthening the side chains (C1–C18) and inserting gauche interactions in the polymeric chain. The results show that in this system, adding gauche interactions has more effect on Tg than lengthening the side chains. Each time a gauche interaction is introduced in the diol segments, Tg increases by 9 °C. Comparisons with other systems are also presented.

Fourier Transform Infrared Spectroscopy Evidence of the Nanoscale Structural Jump in Medium-Rank Tectonic Coal

2021 ◽  
Vol 21 (1) ◽  
pp. 636-645
Author(s):  
Xiaobing Zhang ◽  
Tianrang Jia ◽  
Hang Zhang ◽  
Yiwen Ju ◽  
Yugui Zhang
Keyword(s):  
Molecular Structure ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Structural Parameters ◽  
Fourier Transform Infrared ◽  
Structure Evolution ◽  
Side Chains ◽  
Aromatic System ◽  
Tectonic Coal

Coal is a pressure-sensitive organic rock. The effect of tectonism on the structural evolution of medium-rank coal has been confirmed by the change in the crystal state of tectonic coal, but the organic molecular level response has not been reported. In this paper, three sets of medium-rank tectonic coals and symbiotic nontectonic coals were selected. The distributions of their functional groups and their molecular structure evolution were assessed using Fourier Transform Infrared Spectroscopy (FTIR), and their structural parameters were determined from the curve-fitting analysis. The nanoscale structural jump characteristics and mechanisms of medium-rank tectonic coal were revealed. Compared with symbiotic nontectonic coal, tectonism accelerated the exfoliation of side chains (groups) in the macromolecular structure, enlarged the aromatic system, and removed the unstable groups such as associative hydrogen bonds at first, which indicated that the molecular structure of tectonic coal was affected by nanoscale deformation, showing obvious advanced evolution characteristics. For the fat coal, the removal of side chains (groups) during the formation of tectonic coal makes the aromatic ring condensation obvious. For the coking coal, the formation of tectonic coal is dominated by cycloaliphatic dehydrogenation and aromatization, accompanied by the condensation of the aromatic rings. The tectonic coal formed from lean coal shows obvious aromatization characteristics. The molecular depolymerization and chemical tailoring caused by tectonism promotes the removal of hydrophobic side chains (groups) and activates some polar structure sites in coal. It is considered that the nanoscale structural jump of medium-rank tectonic coal is the result of the competition between the aromatic system and aliphatic structures.

Controlling intermolecular redox-doping of naphthalene diimides

2019 ◽  
Vol 7 (15) ◽  
pp. 4466-4474 ◽  
Author(s):  
Simon B. Schmidt ◽  
Till Biskup ◽  
Xuechen Jiao ◽  
Christopher R. McNeill ◽  
Michael Sommer
Keyword(s):  
Tertiary Amine ◽  
Energy Levels ◽  
Side Chains ◽  
Naphthalene Diimide ◽  
Naphthalene Diimides ◽  
Derivatives Of

Naphthalene diimide (NDI) with tertiary amine side chains is used to n-dope NDI derivatives of varying energy levels.

PEGylated block copolymers containing tertiary amine side-chains cleavable via acid-labile ortho ester linkages for pH-triggered release of DNA

Polymer ◽  
2014 ◽  
Vol 55 (12) ◽  
pp. 2761-2771 ◽  
Author(s):  
Junping Lai ◽  
Zhangyan Xu ◽  
Rupei Tang ◽  
Weihang Ji ◽  
Rui Wang ◽  
...  
Keyword(s):  
Block Copolymers ◽  
Tertiary Amine ◽  
Side Chains ◽  
Triggered Release ◽  
Ortho Ester ◽  
Acid Labile

A cycloaddition approach to tricyclic taxoid skeletons

1995 ◽  
Vol 73 (12) ◽  
pp. 2239-2252 ◽  
Author(s):  
Yee-Fung Lu ◽  
Alex G. Fallis
Keyword(s):  
Diels Alder ◽  
Allylic Oxidation ◽  
Nucleophilic Additions ◽  
Side Chains ◽  
Diterpene Alkaloid ◽  
Thermal Cyclization ◽  
Protecting Group ◽  
Aromatic System ◽  
Microwave Assisted ◽  
Tricyclic Ketone

A cycloaddition approach to the functionalized tricyclo[9.3.1.03,8]pentadecene skeleton contained in Taxol® is described. The cyclohexenone 13 was converted as illustrated to the nitrile-aldehyde 24 to which the diene and acetylenic side chains were attached by sequential nucleophilic additions. Removal of the trimethylsilyl protecting group and Dess–Martin oxidation afforded the triene 35. Microwave-assisted thermal cyclization stereoselectively generated the tricyclic ketone 36 whose structure was further established by conversion to the aromatic system 37 upon treatment with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). An epoxidation sequence was developed to introduce the epimeric C13 alcohol 47 as required for this cycloaddition strategy. Alternatively, an allylic oxidation (CrO3, 3,5-dimethylpyrazole) afforded the C13 ketone 49. Keywords: Taxol®, Diels–Alder, synthesis, diterpene, alkaloid.

scholarly journals How aromatic system size affects the sensitivities of highly energetic molecules?

RSC Advances ◽  
2021 ◽  
Vol 11 (51) ◽  
pp. 31933-31940
Author(s):  
Ivana S. Veljković ◽  
Jelena I. Radovanović ◽  
Dušan Ž. Veljković
Keyword(s):  
Dft Calculations ◽  
Electrostatic Potential ◽  
System Size ◽  
Aromatic System ◽  
Positive Electrostatic Potential

DFT calculations showed that with the increase of the aromatic system size, values of positive electrostatic potential above the central areas of energetic molecules decrease, leading to the decrease in the sensitivities towards detonation.

New tartrate based cyclic phosphoric acids as organocatalysts in Mannich reactions

2016 ◽  
Vol 3 (1) ◽  
Author(s):  
Tuvshinjargal Budragchaa ◽  
Michael Abraham ◽  
Wolfgang Schöfberger ◽  
Alexander Roller ◽  
Michael Widhalm
Keyword(s):  
Crystal Structure ◽  
Dft Calculations ◽  
Structure Analysis ◽  
Mannich Reaction ◽  
Structural Variation ◽  
Crystal Structure Analysis ◽  
Mannich Reactions ◽  
Optimization Study ◽  
The Mannich Reaction ◽  
Phosphoric Acids

Abstract Cyclic phosphoric acids have attracted much attention as chiral organocatalysts. While binaphthol based ligands have been extensively used in various transformations, the analogous TADDOL-type ligands are less explored. A library of seventeen cyclic phosphoric acids with structural variation of the TADDOL backbone were synthesized and an optimization study of the Mannich reaction of aromatic N-(2-hydroxyphenyl)imines with 2,2-dimethyl-1-methoxy-silylenolate was performed. Enantioselectivities between 96% (S) and 70% (R) were observed and a rationalisation, based on crystal structure analysis and DFT calculations, is provided.

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