Selective deshielding of aromatic protons in some ortho-substituted acetanilides

Bartels-Keith, J. R.; Cieciuch, Ronald F. W.

doi:10.1139/v68-422

Cited by 22 publications

(7 citation statements)

References 17 publications

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“…It is known that the interaction through the hydrogen bond pro-duces a deshielding of the hydrogen involved. [24] As can be seen from Figure 12, for the series of halogenated compounds there is increasing deshielding of the H4B signal from fluorine to iodine, which could be due to increasing strength of the IMHB. …”

Section: General Trendsmentioning

confidence: 92%

3‐(Pyridin‐2‐yl)[1,2,3]triazolo[1,5‐a]quinoline: A Theoretical and Experimental Analysis of Ring‐Chain Isomerisation

Ballesteros‐Garrido¹,

Blanco²,

Ballesteros³

et al. 2009

Eur J Org Chem

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In the course of the synthesis of new fluorophores for molecular recognition an experimental (1H NMR) and theoretical (DFT) study of the ring‐chain isomerism of 3‐(pyridin‐2‐yl)[1,2,3]triazolo[1,5‐a]quinoline derivatives (A) into 2‐([1,2,3]triazolo[1,5‐a]pyridin‐3‐yl)quinoline derivatives (B) has been carried out. The rearrangement is influenced by steric and electronic effects of the substituents present on the quinoline ring. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)

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Section: General Trendsmentioning

confidence: 92%

3‐(Pyridin‐2‐yl)[1,2,3]triazolo[1,5‐a]quinoline: A Theoretical and Experimental Analysis of Ring‐Chain Isomerisation

Ballesteros‐Garrido¹,

Blanco²,

Ballesteros³

et al. 2009

Eur J Org Chem

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“…[12] Thus, the large chemical shift observed for H 1 in compound 5a could be simultaneously influenced by the existence of an intramolecular hydrogen bond interaction between this amine hydrogen and the lone pair of one of the oxygen atoms of the nitro group.…”

Section: Nmr Structural Analysis Of 5- 6- 7-and 8-nitrotetrahydro Qmentioning

confidence: 98%

“…The electronic influence of the nitro groups is equally evident in 13 C NMR analysis where, for each of the four nitro derivatives, a larger displacement of the signal of the ipso-C to the nitro substituent compared with the rest of the aromatic C atoms is observed ( On the contrary, it is known that the interaction by hydrogen bond produces a deshielding of the hydrogen involved. [12] Thus, the large chemical shift observed for H 1 in compound 5a could be simultaneously influenced by the existence of an intramolecular hydrogen bond interaction between this amine hydrogen and the lone pair of one of the oxygen atoms of the nitro group.…”

Section: Nmr Structural Analysis Of 5- 6- 7-and 8-nitrotetrahydro Qmentioning

confidence: 98%

Synthesis of 6‐Nitro‐1,2,3,4‐tetrahydroquinoline: An Experimental and Theoretical Study of Regioselective Nitration

et al. 2011

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A revision of the literature on the nitration of tetrahydroquinolines yielded a number of inconsistencies. Thus, we have carried out a thorough study on the nitration of tetrahydroquinoline and several of its N‐protected derivatives both experimentally and at theoretical level. Usually, nitration is carried out in acidic conditions and, thus, tetrahydroquinoline would be N‐protonated; however, if the amino group is protected, the neutral system will be the one undergoing nitration. Different protecting groups have been explored varying, not only electronic and steric effects, but also deprotection conditions. Additionally, different reagents and reaction conditions have been investigated. From this study we have been able to achieve total regioselectivity for nitration at the 6‐position. A very detailed NMR study has been carried out to unequivocally characterise the four nitro isomers. In parallel, a computational study has been performed that is in agreement with the experimental results obtained. With this purpose, all the σ complexes of the four nitro isomers neutral and N‐protonated have been optimized both in gas and water condensed phases by using the B3LYP/6‐31++G** level of computation.

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“…Selectively deshielded aromatic protons in some ortho-substituted acetanilides [12] exhibit signals at unusually low fields for the aromatic proton adjacent to the acetamido group and for the amido proton itself.…”

Section: Introductionmentioning

confidence: 99%

Understanding Chemistry and Unique NMR Characters of Novel Amide and Ester Leflunomide Analogues

et al. 2017

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A series of diverse substituted 5-methyl-isoxazole-4-carboxylic acid amides, imide and esters in which the benzene ring is mono or disubstituted was prepared. Spectroscopic and conformational examination was investigated and a new insight involving steric interference and interesting downfield deviation due to additional diamagnetic anisotropic effect of the amidic carbonyl group and the methine protons in 2,6-diisopropyl-aryl derivative (2) as conformationaly restricted analogues Leflunomide was discussed. Individual substituent electronic effects through π resonance of p-substituents and most stable conformation of compound (2) are discussed.

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Selective deshielding of aromatic protons in some ortho-substituted acetanilides

Cited by 22 publications

References 17 publications

3‐(Pyridin‐2‐yl)[1,2,3]triazolo[1,5‐a]quinoline: A Theoretical and Experimental Analysis of Ring‐Chain Isomerisation

3‐(Pyridin‐2‐yl)[1,2,3]triazolo[1,5‐a]quinoline: A Theoretical and Experimental Analysis of Ring‐Chain Isomerisation

Synthesis of 6‐Nitro‐1,2,3,4‐tetrahydroquinoline: An Experimental and Theoretical Study of Regioselective Nitration

Understanding Chemistry and Unique NMR Characters of Novel Amide and Ester Leflunomide Analogues

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