The Interaction of Carbonyl Groups with Substituents

Wiberg, Kenneth B.

doi:10.1021/ar990008h

Cited by 128 publications

(114 citation statements)

References 32 publications

(54 reference statements)

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“…As the earlier model with two canonical structures did not explain these results, one that incorporated a carbonyl dipolar canonical form was suggested (2). Therefore, the rotational barrier is attributed mainly to the resonance structures 2/3 and 5/6 [22,23].…”

mentioning

confidence: 69%

“…Moreover, an insignificant difference in charge density at the oxygen was observed in the planar form and the transition state. Hence, the oxygen is assumed to simply polarize the C-O bond, resulting in a large δ + on the carbon [22]. As the earlier model with two canonical structures did not explain these results, one that incorporated a carbonyl dipolar canonical form was suggested (2).…”

mentioning

confidence: 84%

“…The disruption of favorable interactions between N and C raises the rotational barrier. In the case of formamide, the barrier is 18 kcal mol −1 [22][23][24][25]. Wiberg et al conducted theoretical studies concerning the amide bond rotation.…”

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confidence: 99%

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Characterization of Amide Bond Conformers for a Novel Heterocyclic Template of N-acylhydrazone Derivatives

et al. 2013

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Herein we describe NMR experiments and structural modifications of 4-methyl-2-phenylpyrimidine-N-acylhydrazone compounds (aryl-NAH) in order to discover if duplication of some signals in their 1 H-and 13 C-NMR spectra was related to a mixture of imine double bond stereoisomers (E/Z) or CO-NH bond conformers (syn and anti-periplanar). NMR data from NOEdiff, 2D-NOESY and 1 H-NMR spectra at different temperatures, and also the synthesis of isopropylidene hydrazone revealed the nature of duplicated signals of a 4-methyl-2-phenylpyrimidine-N-acylhydrazone derivative as a mixture of two conformers in solution. Further we investigated the stereoelectronic influence of substituents at the ortho position on the pyrimidine ring with respect to the carbonyl group, as well as the OPEN ACCESSMolecules 2013, 18 11684 electronic effects of pyrimidine by changing it to phenyl. The conformer equilibrium was attributed to the decoplanarization of the aromatic ring and carbonyl group (generated by an ortho-alkyl group) and/or the electron withdrawing character of the pyrimidine ring. Both effects increased the rotational barrier of the C-N amide bond, as verified by the ΔG ≠ values calculated from dynamic NMR. As far as we know, it is the first description of aryl-NAH compounds presenting two CO-NH bond-related conformations.

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Characterization of Amide Bond Conformers for a Novel Heterocyclic Template of N-acylhydrazone Derivatives

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“…The addition to water to carbonyl compounds follows an overall process (1) [3][4][5][6][7] . Only some structural effects will be therefore briefly discussed here.…”

Section: Covalent Additions To a Carbonyl Groupmentioning

confidence: 99%

“…Some of the aspects of covalent addition to carbonyl groups has already been extensively reviewed [3][4][5][6][7] with stress on reactions of aliphatic compounds. Therefore this aspect is in the present review treated only briefly.…”

Section: Introductionmentioning

confidence: 99%

Additions of water, hydroxide ions, alcohols and alkoxide ions to carbonyl and azomethine bonds

Zuman¹

2002

Arkivoc

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In this review are discussed equilibria involved in nucleophilic additions of H 2 O, HO -, ROH, and RO -(where R is an alkyl) to compounds containing carbonyl and azomethine bonds. These reactions result in a formation of covalent bonds between the heteroatom of the nucleophile and the carbon of the carbonyl double bond. After a brief summary of reactions resulting in additions to aliphatic carbonyl compounds, attention is paid to additions to benzaldehydes and formyl aromatic heterocycles. Equilibria involving additions to pyridoxal and some related compounds are dealt with in some detail. Discussion of additions of stated nucleophiles to azomethine bonds is practically restricted to additions to C=N bonds in heterocyclic rings. The reactivity of nucleophiles in such additions depends on the number of heteroatoms (in particular nitrogen) in the attacked ring, as well as on the number and position of substituents in such rings. In polynuclear compounds the reactivity depends on the number and kind of annelled rings, on the number and mutual position of heteroatoms and on the kind, number and position of substituents. In particular additions to pyrimidines, quinazolines, 1,2,4-and 1,3,5-triazines, pteridines and other heterocycles with four nitrogens, as well as 8-azapurines are mentioned.

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Reactions of Aldehydes and Ketones and Their Derivatives

Murray¹

Organic Reaction Mechanisms• 1999

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The Interaction of Carbonyl Groups with Substituents

Cited by 128 publications

References 32 publications

Characterization of Amide Bond Conformers for a Novel Heterocyclic Template of N-acylhydrazone Derivatives

Characterization of Amide Bond Conformers for a Novel Heterocyclic Template of N-acylhydrazone Derivatives

Additions of water, hydroxide ions, alcohols and alkoxide ions to carbonyl and azomethine bonds

Reactions of Aldehydes and Ketones and Their Derivatives

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