scholarly journals An efficient computational model to predict protonation at the amide nitrogen and reactivity along the C–N rotational pathway

2015 ◽  
Vol 51 (29) ◽  
pp. 6395-6398 ◽  
Author(s):  
Roman Szostak ◽  
Jeffrey Aubé ◽  
Michal Szostak
Keyword(s):  
Nitrogen Atom ◽  
Computational Model ◽  
Amide Bond ◽  
Amide Nitrogen

A computational model enabling prediction of protonation at the amide bond nitrogen atom along the C–N rotational pathway is reported.

scholarly journals Unexpected Resistance to Base-Catalyzed Hydrolysis of Nitrogen Pyramidal Amides Based on the 7-Azabicyclic[2.2.1]heptane Scaffold

Molecules ◽  
2018 ◽  
Vol 23 (9) ◽  
pp. 2363 ◽  
Author(s):  
Diego Ocampo Gutiérrez de Velasco ◽  
Aoze Su ◽  
Luhan Zhai ◽  
Satowa Kinoshita ◽  
Yuko Otani ◽  
...  
Keyword(s):  
Nitrogen Atom ◽  
Amide Bond ◽  
Free Energies ◽  
Amide Nitrogen ◽  
Bond Rotation ◽  
Entropy Term ◽  
And Inversion ◽  
Kinetics Of ◽  
Hydrolysis Of ◽  
Amide Nitrogen Atom

Non-planar amides are usually transitional structures, that are involved in amide bond rotation and inversion of the nitrogen atom, but some ground-minimum non-planar amides have been reported. Non-planar amides are generally sensitive to water or other nucleophiles, so that the amide bond is readily cleaved. In this article, we examine the reactivity profile of the base-catalyzed hydrolysis of 7-azabicyclo[2.2.1]heptane amides, which show pyramidalization of the amide nitrogen atom, and we compare the kinetics of the base-catalyzed hydrolysis of the benzamides of 7-azabicyclo[2.2.1]heptane and related monocyclic compounds. Unexpectedly, non-planar amides based on the 7-azabicyclo[2.2.1]heptane scaffold were found to be resistant to base-catalyzed hydrolysis. The calculated Gibbs free energies were consistent with this experimental finding. The contribution of thermal corrections (entropy term, –TΔS‡) was large; the entropy term (ΔS‡) took a large negative value, indicating significant order in the transition structure, which includes solvating water molecules.

Influence of alkyl group on amide nitrogen atom on fluorescence quenching of tyrosine amide and N-acetyltyrosine amide

2004 ◽  
Vol 111 (2) ◽  
pp. 105-113 ◽  
Author(s):  
Justyna Mrozek ◽  
Alicja Rzeska ◽  
Katarzyna Guzow ◽  
Jerzy Karolczak ◽  
Wiesław Wiczk
Keyword(s):  
Nitrogen Atom ◽  
Fluorescence Quenching ◽  
Alkyl Group ◽  
Amide Nitrogen ◽  
Amide Nitrogen Atom

Micellar Catalysis of Organic Reactions. XVII. Hydrolysis of Nitrazepam and Some N-Alkylated Derivatives

1985 ◽  
Vol 38 (7) ◽  
pp. 1037 ◽  
Author(s):  
TJ Broxton ◽  
SR Morrison
Keyword(s):  
Aqueous Solution ◽  
Nitrogen Atom ◽  
Sodium Dodecyl Sulfate ◽  
Sodium Dodecyl ◽  
Initial Attack ◽  
Amide Nitrogen ◽  
High Acid ◽  
Alkyl Derivatives ◽  
Hydrolysis Of ◽  
Amide Nitrogen Atom

Product studies for the acid catalysed hydrolysis of nitrazepam and some N-alkyl derivatives in the presence of micelles of sodium dodecyl sulfate ( sds ) have been carried out by a U.V. spectrophotometric technique. Attack of water at C2 leading to initial amide cleavage is favoured by high acid concentrations, by micelles of sds and by small R groups attached to the amide nitrogen atom. For nitrazepam, a change of mechanism from water attack at C5 (leading to initial azomethine cleavage) to water attack at C2 (leading to initial amide cleavage) was observed on transfer from water to micelles of sds . For N-benzyl nitrazepam (1d), however, no change of mechanism was detected. Initial attack of water occurred at C5 (leading to initial azomethine cleavage), both in aqueous solution and in micelles of sds.

KI-catalyzed imidation of sp3 C–H bond adjacent to amide nitrogen atom

2012 ◽  
Vol 10 (39) ◽  
pp. 7869 ◽  
Author(s):  
Zhi-Qi Lao ◽  
Wen-He Zhong ◽  
Qing-Hua Lou ◽  
Zhong-Jun Li ◽  
Xiang-Bao Meng
Keyword(s):  
Nitrogen Atom ◽  
Amide Nitrogen ◽  
Amide Nitrogen Atom

scholarly journals Heteroatom Substitution at Amide Nitrogen—Resonance Reduction and HERON Reactions of Anomeric Amides

Molecules ◽  
2018 ◽  
Vol 23 (11) ◽  
pp. 2834 ◽  
Author(s):  
Stephen Glover ◽  
Adam Rosser
Keyword(s):  
Amide Bond ◽  
Anomeric Effect ◽  
Amide Nitrogen ◽  
Carbonyl Carbon ◽  
Heteroatom Substitution ◽  
Electronegative Atom ◽  
Anomeric Effects ◽  
Acyl Derivatives

This review describes how resonance in amides is greatly affected upon substitution at nitrogen by two electronegative atoms. Nitrogen becomes strongly pyramidal and resonance stabilisation, evaluated computationally, can be reduced to as little as 50% that of N,N-dimethylacetamide. However, this occurs without significant twisting about the amide bond, which is borne out both experimentally and theoretically. In certain configurations, reduced resonance and pronounced anomeric effects between heteroatom substituents are instrumental in driving the HERON (Heteroatom Rearrangement On Nitrogen) reaction, in which the more electronegative atom migrates from nitrogen to the carbonyl carbon in concert with heterolysis of the amide bond, to generate acyl derivatives and heteroatom-substituted nitrenes. In other cases the anomeric effect facilitates SN1 and SN2 reactivity at the amide nitrogen.

The HERON reaction — Origin, theoretical background, and prevalence

2005 ◽  
Vol 83 (9) ◽  
pp. 1492-1509 ◽  
Author(s):  
Stephen A Glover ◽  
Arvi Rauk ◽  
Jeanne M Buccigross ◽  
John J Campbell ◽  
Gerard P Hammond ◽  
...  
Keyword(s):  
Gas Phase ◽  
Theoretical Basis ◽  
Historical Perspective ◽  
Theoretical Background ◽  
Amide Bond ◽  
Chemical Transformations ◽  
Amide Nitrogen ◽  
Gas Phase Reactions ◽  
Physical Organic ◽  
Computational Work

The origin of the HERON reaction is reviewed from a historical perspective and shown to have its foundation in the unusual properties of bisheteroatom-substituted amides, so-called anomeric amides. The reaction involves migration of anomerically destabilized oxo-substituents on an amide nitrogen to the amide carbon and dissociation of the amide bond. Computational work providing a theoretical basis for the reaction is presented, together with physical organic measurements that support results therefrom. The rearrangement has been observed in a number of chemical transformations of N-alkoxy-N-aminoamides, reactions of 1-acyloxy-1-alkoxydiazenes, N-alkoxy-N-aminocarbamates, N-alkoxyhydroxamic acids, as well as in the gas-phase reactions of N-acyloxy-N-alkoxyamides.Key words: HERON reaction, anomeric amides, rearrangements, hindered esters, concerted reactions.

Partition coefficients and ultraviolet absorption maxima for the cinnamoyl derivatives of some long-chain and large-ring amines

1970 ◽  
Vol 48 (8) ◽  
pp. 1340-1343 ◽  
Author(s):  
D. J. Currie ◽  
H. L. Holmes
Keyword(s):  
Nitrogen Atom ◽  
Chain Length ◽  
Partition Coefficients ◽  
The Other ◽  
Ring Size ◽  
Amide Nitrogen ◽  
Derivatives Of ◽  
Limiting Value ◽  
Long Chain ◽  
Amide Nitrogen Atom

Partition coefficients of the title compounds in the system cyclohexane–water do not increase steadily with increasing chain length or ring size but level off to a limiting value. Reasons are advanced to account for this observation. Absorption maxima, on the other hand, are not influenced by the size of the ring or the length of the chain but are dependent only upon the degree of substitution on the amide nitrogen atom.

scholarly journals Synthesis and optical properties of poly(p-benzamide)s bearing oligothiophene on the amide nitrogen atom through an alkylene spacer

2013 ◽  
Vol 45 (12) ◽  
pp. 1171-1176 ◽  
Author(s):  
Koji Takagi ◽  
Katsuya Nobuke ◽  
Yuma Nishikawa ◽  
Ryohei Yamakado
Keyword(s):  
Optical Properties ◽  
Nitrogen Atom ◽  
Amide Nitrogen ◽  
Amide Nitrogen Atom
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