F. W. Wehrli, A. P. Marchand and S. Wehrli. Interpretation of carbon‐13 NMR spectra. Wiley, Chichester, New York, Brisbane, Toronto, Singapore, 2nd Edition, 1988, 484 pp. £37.50

Wehrli, Félix W.; Marchand, Alan P.; Wehrli, Suzanne; Griffiths, D. Vaughan

doi:10.1002/mrc.1260270520

Cited by 56 publications

(79 citation statements)

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“…Rifamycins [79][80][81] are antibiotics belonging to the group of naphthalenic ansamycins [82] characterized by an aliphatic bridge (polypropionate chain) linking two nonadjacent centers of an aromatic moiety. They are produced from Streptomyces mediterranei [83] and are active against a large variety of organisms; including bacteria, eukaryotes, and viruses [84].…”

Section: Expeditious Asymmetric Synthesis Of the Stereoheptad C 19 -Cmentioning

confidence: 99%

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Vogel

Turks

Bouchez

et al. 2008

Pure and Applied Chemistry

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At low temperature and in the presence of an acid catalyst, SO 2 adds to 1,3-dienes equilibrating with the corresponding 3,6-dihydro-1,2-oxathiin-2-oxides (sultines). These compounds are unstable above -60°C and equilibrate with the more stable 2,5-dihydrothiophene 1,1-dioxides (sulfolenes). The hetero-Diels-Alder additions of SO 2 are suprafacial and follow the Alder endo rule. The sultines derived from 1-oxy-substituted and 1,3-dioxydisubstituted 1,3-dienes cannot be observed at -100°C but are believed to be formed faster than the corresponding sulfolenes. In the presence of acid catalysts, the 6-oxy-substituted sultines equilibrate with zwitterionic species that react with electron-rich alkenes such as enoxysilanes and allylsilanes, generating β,γ-unsaturated silyl sulfinates that can be desilylated and desulfinylated to generate polypropionate fragments containing up to three contiguous stereogenic centers and an (E)-alkene unit. Alternatively, the silyl sulfinates can be reacted with electrophiles to generate polyfunctional sulfones (one-pot, four-component synthesis of sulfones), or oxidized into sulfonyl chlorides and reacted with amines, then realizing a one-pot, four-component synthesis of polyfunctional sulfonamides. Using enantiomerically enriched dienes such as 1-[(R)-or 1-(S)-phenylethyloxy]-2-methyl-(E,E)-penta-1,3-dien-3-yl isobutyrate, derived from inexpensive (R)-or (S)-1-phenylethanol, enantiomerically enriched stereotriads are obtained in one-pot operations. The latter are ready for further chain elongation. This has permitted the development of expeditious total asymmetric syntheses of important natural products of biological interest such as the baconipyrones, rifamycin S, and apoptolidin A.

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Section: Expeditious Asymmetric Synthesis Of the Stereoheptad C 19 -Cmentioning

confidence: 99%

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Vogel

Turks

Bouchez

et al. 2008

Pure and Applied Chemistry

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“…In aqueous solutions the chemical shift of the α-carbon of glycine was used as a chemical reference as described previously [23]. For non-aqueous solvents either 10 % tetramethylsilane was used as an internal standard or an appropriate solvent signal was used as a secondary reference [24].…”

Section: Table 1 Dissociation Constants Of Aldehyde (R-h) and Glyoxalmentioning

confidence: 99%

A 13C-NMR study of the inhibition of papain by a dipeptide-glyoxal inhibitor

Lowther

Djurdjevic-Pahl

Hewage

et al. 2002

Biochemical Journal

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Z-Phe-Ala-glyoxal (where Z is benzyloxycarbonyl) has been synthesized and shown to be a competitive inhibitor of papain with a Ki = 3.30±0.25nM. 13C-NMR has been used to show that in aqueous media, Z-Phe-[2-13C]Ala-glyoxal gives signals at 207.7p.p.m. and 96.3p.p.m. showing that both the α-keto carbon and its hydrate are present. When this inhibitor is bound to papain a single signal at 209.7p.p.m. is observed due to the 13C-enriched carbon. This demonstrates that the glyoxal α-keto carbon is not hydrated when it is bound to papain and that it does not form a thiohemiketal with the thiol group of Cys-25. Z-Phe-[1-13C]Ala-glyoxal has also been synthesized and its aldehyde carbon is fully hydrated in aqueous solution giving signals at 88.7p.p.m. and 90.2p.p.m. when the α-keto carbon and its hydrate are present respectively. When this inhibitor is bound to papain a single signal at 71.04p.p.m. was observed due to the 13C-enriched carbon showing that the 13C-enriched aldehyde carbon forms a thiohemiacetal with Cys-25.

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“…11 Solid-state 9 Be NMR has been used recently for characterizing a variety of minerals, 12 which are comparatively nontoxic; 13 however, simpler systems composed of relatively small molecules remain generally unexamined. Bis(2,4-pentanedionato-O,O′)beryllium [bis(acetylacetonato)beryllium(II), Be(acac) 2 ] was first examined in solution using 9 Be NMR by Wehrli 14 and more recently by Kanakubo et al 15 Unfortunately, the dual-spin probe relaxation method employed in these solution studies can only provide [C Q 2 (1 + η 2 /3)] 1/2 , where C Q is the nuclear quadrupole coupling constant and η is the asymmetry parameter. In addition, solution studies provide no information on CS tensors.…”

Section: Introductionmentioning

confidence: 99%

“…It has been stated in the literature that the shielding range of 9 Be is no greater than that of hydrogen. 25 Although numerous 1 H shielding tensors have been characterized, 26 to date no experimental characterization of a 9 Be shielding tensor has been reported.…”

Section: Introductionmentioning

confidence: 99%

Beryllium-9 NMR Study of Solid Bis(2,4-pentanedionato-O,O‘)beryllium and Theoretical Studies of ⁹Be Electric Field Gradient and Chemical Shielding Tensors. First Evidence for Anisotropic Beryllium Shielding

Bryce

Wasylishen

1999

J. Phys. Chem. A

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Despite the favorable NMR properties of 9 Be (I ) 3 / 2 ), NMR spectroscopy of this nucleus in the solid state remains comparatively unexplored, perhaps owing to the extreme toxicity of beryllium and its compounds. We present here an integrated experimental and theoretical study of the Be chemical shielding (CS) and electric field gradient (EFG) tensors in bis(2,4-pentanedionato-O,O′)beryllium [Be(acac) 2 ]. Interpretation of the 9 Be NMR data was facilitated by crystal X-ray diffraction results, which indicate two crystallographically unique sites (Onuma, S.; Shibata, S. Acta Crystallogr. 1985, C41, 1181). Beryllium-9 NMR spectra acquired at 4.7 and 9.4 T for magic-angle spinning (MAS) and stationary samples have been fitted in order to extract the nuclear quadrupole coupling constant (C Q ), asymmetry parameter (η), and isotropic chemical shift (δ iso ). The best-fit nuclear quadrupole parameters for the two sites were determined to be C Q (1) ) -294 ( 4 kHz, η(1) ) 0.11 ( 0.04; C Q (2) ) -300 ( 4 kHz, η(2) ) 0.15 ( 0.02. Our analyses of the stationary samples also reveal a definite anisotropy in the beryllium CS tensor and allow us to place upper and lower limits on the spans of 7 and 3 ppm. This is the first evidence for anisotropic shielding in beryllium. Ab initio calculations of the beryllium CS tensors in Be(acac) 2 at the RHF level indicate spans ranging from 7 to 9 ppm; this represents a substantial fraction of the total known chemical shift range for Be (<50 ppm). The calculated C Q s are also in good agreement with the experimental results. To put the Be(acac) 2 results in context, calculations of the beryllium CS tensors for a series of compounds encompassing the known range of 9 Be chemical shifts are also presented. The calculations are in outstanding accord with experimental data from the literature. On the basis of calculations for linear molecules, it is shown that the assumption that the 9 Be chemical shift is governed essentially by the diamagnetic term is erroneous. For some of these molecules, the calculated Be CS tensor spans are greater than the total known chemical shift range.

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F. W. Wehrli, A. P. Marchand and S. Wehrli. Interpretation of carbon‐13 NMR spectra. Wiley, Chichester, New York, Brisbane, Toronto, Singapore, 2nd Edition, 1988, 484 pp. £37.50

Cited by 56 publications

References 0 publications

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

A 13C-NMR study of the inhibition of papain by a dipeptide-glyoxal inhibitor

Beryllium-9 NMR Study of Solid Bis(2,4-pentanedionato-O,O‘)beryllium and Theoretical Studies of ⁹Be Electric Field Gradient and Chemical Shielding Tensors. First Evidence for Anisotropic Beryllium Shielding

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F. W. Wehrli, A. P. Marchand and S. Wehrli. Interpretation of carbon‐13 NMR spectra. Wiley, Chichester, New York, Brisbane, Toronto, Singapore, 2nd Edition, 1988, 484 pp. £37.50

Cited by 56 publications

References 0 publications

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

Use of sultines in the asymmetric synthesis of polypropionate antibiotics

A 13C-NMR study of the inhibition of papain by a dipeptide-glyoxal inhibitor

Beryllium-9 NMR Study of Solid Bis(2,4-pentanedionato-O,O‘)beryllium and Theoretical Studies of 9Be Electric Field Gradient and Chemical Shielding Tensors. First Evidence for Anisotropic Beryllium Shielding

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Product

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About

Beryllium-9 NMR Study of Solid Bis(2,4-pentanedionato-O,O‘)beryllium and Theoretical Studies of ⁹Be Electric Field Gradient and Chemical Shielding Tensors. First Evidence for Anisotropic Beryllium Shielding