<sup>1</sup>H NMR Study of Hydrogen Bonding and Hydrogen to Deuterium Isotope Exchange in Ureido Sugars

Wawer, A.; Wawer, Iwona; Piekarska-Bartoszewicz, Bogusława; Temeriusz, Andrzej

doi:10.1080/00387019608007274

Cited by 3 publications

(3 citation statements)

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“…We consider effective intramolecular H-bonding to be responsible for the slow proton exchange. 12 Oximation of the α-oxo functionality of the tertiary amides furnished two geometrical isomers in the case of the pyruvic acid derivative, i.e. (E )-and (Z )-8c whilst only the (Z )-isomer formed from the benzoylformic acid derivative, i.e.…”

Section: Resultsmentioning

confidence: 99%

“…Each of these oximes, like their α-keto precursors, displayed evidence in their 1 H NMR spectra for the existence of two conformers differing in the rotameric state of the tertiary amide bond [e.g. the 13 C NMR spectrum of (E )-8c exhibits CH 3 signals at 12.08 and 12.25 ppm whilst the corresponding carbon atom of (Z )-8c resonates at 16.88 and 17.26 13 ]. Rotamer ratios for the oximes are as follows: (E )-8c 1 : 1.2; (Z )-8c 1 : 1 and (Z )-8d 1 : 1.2.…”

Section: Resultsmentioning

confidence: 99%

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α-Keto amides as precursors to heterocycles—generation and cycloaddition reactions of piperazin-5-one nitrones

et al. 2003

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α-Keto amides 10a,b, formed from reaction of pyruvic or benzoylformic acid with allyl amine are found to present as single rotameric forms whilst their tertiary amido analogues 10c,d present as two rotamers in solution at rt. The hydroxyimino derivatives 8 share the conformational characteristics of their parents. The geometrical make-up of the new α-amidooximes is seen to depend on the structure of the starting acid and on the degree of substitution of the amido group. The oxime 8a derived from pyruvic acid and allyl amine is formed solely as the (E )-isomer whilst its tertiary amido analogue 8c is formed as both (E )-and (Z )-isomers. Oximes derived from benzoylformic acid have the opposite selectivity with both geometrical isomers forming from the secondary amide 8b and only the (Z )-isomer from the tertiary amide 8d. With the exception of 8b all oximes were configurationally stable with (Z )-isomers reacting to form isoxazolopyrrolidinones 11-compounds with a relatively rare bicyclic nucleus and (E )-isomers cyclising to piperazin-5-one nitrones 1-ketopiperazine N-oxides have to date only appeared once in the literature. New nitrones were trapped with phenyl vinyl sulfone, dimethyl acetylenedicarboxylate and methyl propiolate yielding isoxazolidine and isoxazoline fused piperazinones 13,15,21 and 22. Cycloadducts from dimethyl acetylenedicarboxylate and 8a,b are thermally labile and their rearrangement provides a novel route to pyrrolopiperazinones 16. The structure of a representative isoxazolopyrrolidinone, 11c, and a 2,3-dihydroisoxazoline fused piperazinone, 21b, are unambiguously solved following x-ray structural analysis.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

α-Keto amides as precursors to heterocycles—generation and cycloaddition reactions of piperazin-5-one nitrones

et al. 2003

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“…18 Hence, this work is a continuation of our spectroscopic studies (FTIR, ] H NMR and 13 C CP/MAS) which were applied to gain information about the conformational and hydrogen bonding properties of these compounds. 19 ' 20…”

Section: Introductionmentioning

confidence: 98%

Intramolecular Hydrogen Bonding In N-(2-Amino-2-Deoxy-β-D-Glucopyranoside)-N'-Carbamoyl-L-Dipeptidylesters: An Infrared And ¹H Nmr Study

Plass

Weychert

Wawer

et al. 2000

Journal of Carbohydrate Chemistry

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Ten A^-(2-amino-2-deoxy-P-D-glucopyranoside)-//'-carbamoyl-L-dipeptidylesters with different amino acid sequences in the dipeptide unit were studied by means of IR and 'H NMR spectroscopy. In the IR spectra three bands at 3453, 3420 and 3390 cm' 1 were observed which could be assigned to the free NH, the intramolecularly hydrogen bonded NH species forming five-membered, C5, and seven-membered, C7, rings, respectively. Comparing the NH band positions which correspond to the C7 rings of the Gly-Xaa and the Xaa-Gly dipeptidylesters, the signals of the Xaa-Gly sequence were shifted by 10 cm' 1 to lower wave numbers indicating stronger hydrogen bonds. The temperature effect dv/dT was an order of magnitude larger for the C7 associates than for C5 showing the highest enthalpy of the C7 hydrogen bond. The *H NMR spectra give three separate signals for the NH groups. The temperature coefficient A5/AT was the 1059

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First α-deuterium nitroxides; synthesis and EPR study

et al. 2019

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¹H NMR Study of Hydrogen Bonding and Hydrogen to Deuterium Isotope Exchange in Ureido Sugars

Cited by 3 publications

References 9 publications

α-Keto amides as precursors to heterocycles—generation and cycloaddition reactions of piperazin-5-one nitrones

α-Keto amides as precursors to heterocycles—generation and cycloaddition reactions of piperazin-5-one nitrones

Intramolecular Hydrogen Bonding In N-(2-Amino-2-Deoxy-β-D-Glucopyranoside)-N'-Carbamoyl-L-Dipeptidylesters: An Infrared And ¹H Nmr Study

First α-deuterium nitroxides; synthesis and EPR study

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1H NMR Study of Hydrogen Bonding and Hydrogen to Deuterium Isotope Exchange in Ureido Sugars

Cited by 3 publications

References 9 publications

α-Keto amides as precursors to heterocycles—generation and cycloaddition reactions of piperazin-5-one nitrones

α-Keto amides as precursors to heterocycles—generation and cycloaddition reactions of piperazin-5-one nitrones

Intramolecular Hydrogen Bonding In N-(2-Amino-2-Deoxy-β-D-Glucopyranoside)-N'-Carbamoyl-L-Dipeptidylesters: An Infrared And 1H Nmr Study

First α-deuterium nitroxides; synthesis and EPR study

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¹H NMR Study of Hydrogen Bonding and Hydrogen to Deuterium Isotope Exchange in Ureido Sugars

Intramolecular Hydrogen Bonding In N-(2-Amino-2-Deoxy-β-D-Glucopyranoside)-N'-Carbamoyl-L-Dipeptidylesters: An Infrared And ¹H Nmr Study