NMR study of E/Z isomerism in N‐alkoxybenzoimidic acid derivatives

Schraml, Jan; Blechta, Vratislav; Karban, Jindřich; Mindl, Jaromír

doi:10.1002/mrc.1076

Cited by 2 publications

(1 citation statement)

References 15 publications

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“…32 With the exception of the ortho-chloro derivative, we see only one set of signals in all the NMR spectra. In contrast, in aliphatic hydroxamic or dihydroxamic acids the two conformers of the hydroxamic group, E and Z, differ in their 15 4,6 similar differences are seen in the spectra of anomalous 2-chloro derivative.…”

Section: Solution Chemical Shiftsmentioning

confidence: 96%

Ring‐substituted benzohydroxamic acids: ¹H, ¹³C and ¹⁵N NMR spectra and NHOH proton exchange

Schraml

Tkadlecová

Pataridis

et al. 2005

Magnetic Reson in Chemistry

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NMR spectra (1H, 13C, 15N) of para- and meta-substituted benzohydroxamic acids were studied in dry dimethyl sulfoxide solutions. The 13C chemical shifts were very close to those found by cross-polarization magic angle spinning in solids, the hydroxamic (not hydroximic) structure of which is unambiguous. The hydroxamic structure of these acids in DMSO solutions was proved independently by their 15N chemical shifts. The 15N and 1H chemical shifts of the NH-OH fragment showed excellent mutual dependences and dependences on the nature of the ring substituent. According to these dependences and ab initio energy calculations, all the acids assume the same Z conformation. Proton exchange between hydroxamic OH and NH groups in DMSO proceeded by both intra- and intermolecular exchange and the rates did not exhibit any simple relationship to the substituent constants.

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Section: Solution Chemical Shiftsmentioning

confidence: 96%

Ring‐substituted benzohydroxamic acids: ¹H, ¹³C and ¹⁵N NMR spectra and NHOH proton exchange

Schraml

Tkadlecová

Pataridis

et al. 2005

Magnetic Reson in Chemistry

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¹⁵N chemical shifts of a series of isatin oxime ethers and their corresponding nitrone isomers

Xiao-hong

Huang

Sin

et al. 2010

Magnetic Reson in Chemistry

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In this article, we describe the characteristic (15)N chemical shifts of isatin oxime ethers and their isomer nitrone. These oxime ethers and nitrones are the alkylation reaction products of isatin oximes. In our study, the (15)N chemical shifts observed in these oxime ethers were in the 402-408 (or 22-28) ppm range, although those for their corresponding nitrone series were in the 280-320 (or -100 to -60) ppm range. This remarkable difference in (15)N NMR chemical shift values could potentially be used to determine the O- versus N-alkylation of oximes, even when only one isomer is available. In this paper, the differences in (15)N NMR chemical shifts serve as the basis for a discussion about how to distinguish both regioisomers derived from the oximes alkylation.

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NMR study of E/Z isomerism in N‐alkoxybenzoimidic acid derivatives

Cited by 2 publications

References 15 publications

Ring‐substituted benzohydroxamic acids: ¹H, ¹³C and ¹⁵N NMR spectra and NHOH proton exchange

Ring‐substituted benzohydroxamic acids: ¹H, ¹³C and ¹⁵N NMR spectra and NHOH proton exchange

¹⁵N chemical shifts of a series of isatin oxime ethers and their corresponding nitrone isomers

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NMR study of E/Z isomerism in N‐alkoxybenzoimidic acid derivatives

Cited by 2 publications

References 15 publications

Ring‐substituted benzohydroxamic acids: 1H, 13C and 15N NMR spectra and NHOH proton exchange

Ring‐substituted benzohydroxamic acids: 1H, 13C and 15N NMR spectra and NHOH proton exchange

15N chemical shifts of a series of isatin oxime ethers and their corresponding nitrone isomers

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Ring‐substituted benzohydroxamic acids: ¹H, ¹³C and ¹⁵N NMR spectra and NHOH proton exchange

Ring‐substituted benzohydroxamic acids: ¹H, ¹³C and ¹⁵N NMR spectra and NHOH proton exchange

¹⁵N chemical shifts of a series of isatin oxime ethers and their corresponding nitrone isomers