Conformational analysis. Part 30.1 The conformational analysis of some lactones by the lanthanide induced shift (LIS) technique

Abraham, Raymond J.; Ghersi, A.; Petrillo, Giovanni; Sancassan, Fernando

doi:10.1039/a700159b

Cited by 25 publications

(23 citation statements)

References 31 publications

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“…Similar behavior has been inferred in the equilibrium of the model compounds 4-hydroxy-δ-valerolactone and 4-hydroxymethyl-γ-butyrolactone (Scheme 5). [39,40] In addition, there is an unfavorable steric interaction for the lactones 4a and 6a between the equatorial substituent on C-2 and the ester functionality in the 4 H 3 conformation adopted by these lactones (Figure 2). [3] Scheme 5…”

Section: Isomerization Reactions Thermodynamic Considerationsmentioning

confidence: 97%

δ‐Galactonolactone: Synthesis, Isolation, and Comparative Structure and Stability Analysis of an Elusive Sugar Derivative

Bierenstiel

Schlaf

2004

Eur J Org Chem

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δ‐D‐Gluconolactone, δ‐D‐mannonolactone, and — for the first time — the thermodynamically unstable δ‐D‐galactonolactone have been prepared and isolated from DMF solution by oxidizing the corresponding sugars with Shvo’s catalyst [(C4Ph4CO)(CO)2Ru]2 and a hydrogen acceptor. The preferred conformation of δ‐D‐galactonolactone in [D6]DMSO solution has been determined by 1H NMR spectroscopy experiments and DFT calculations to be 4H3 and is compared to those of the previously established conformations of δ‐D‐gluconolactone (4H3) and δ‐D‐mannonolactone (B2,5). The conformations of the lactones suggest an explanation for their relative rates of isomerization to their respective γ‐D‐lactones by an intramolecular mechanism. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

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Section: Isomerization Reactions Thermodynamic Considerationsmentioning

confidence: 97%

δ‐Galactonolactone: Synthesis, Isolation, and Comparative Structure and Stability Analysis of an Elusive Sugar Derivative

Bierenstiel

Schlaf

2004

Eur J Org Chem

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“…The dihedral angle between the ester group and the benzene ring was determined from a lanthanide-induced shift (LIS) investigation using the LIRAS program; 51,52 full details will be given elsewhere (R. J. Abraham, F. Sancassan and M. Mobli, to be published). It is convenient to summarize here the results from this analysis.…”

Section: Phenyl Acetate (5)mentioning

confidence: 99%

¹H chemical shifts in NMR. Part 21—Prediction of the ¹H chemical shifts of molecules containing the ester group: a modelling and ab initio investigation

Abraham

Bardsley

Mobli

et al. 2004

Magnetic Reson in Chemistry

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The 1H NMR spectra of 24 compounds containing the ester group are given and assigned. These data were used to investigate the effect of the ester group on the 1H chemical shifts in these molecules. These effects were analysed using the CHARGE model, which incorporates the electric field, magnetic anisotropy and steric effects of the functional group for long-range protons together with functions for the calculation of the two- and three-bond effects. The effect of the ester electric field was given by considering the partial atomic charges on the three atoms of the ester group. The anisotropy of the carbonyl group was reproduced with an asymmetric magnetic anisotropy acting at the midpoint of the carbonyl bond with values of Deltachi(parl) and Deltachi(perp) of 10.1 x 10(-30) and -17.1 x 10(-30) cm3 molecule(-1). An aromatic ring current (=0.3 times the benzene ring current) was found to be necessary for pyrone but none for maleic anhydride. This result was confirmed by GIAO calculations. The observed 1H chemical shifts in the above compounds were compared with those calculated by CHARGE and the ab initio GIAO method (B3LYP/6-31G**). For the 24 compounds investigated with 150 1H chemical shifts spanning a range of ca 10 ppm, the CHARGE model gave an excellent r.m.s. error (obs - calc) of <0.1 ppm. The GIAO calculations gave a very reasonable r.m.s. error of ca 0.2 ppm although larger deviations of ca 0.5 ppm were observed for protons near to the electronegative atoms. The accurate predictions of the 1H chemical shifts given by the CHARGE model were used in the conformational analysis of the vinyl esters methyl acrylate and methyl crotonate. An illustration of the use of the CHARGE model in the prediction of the 1H spectrum of a complex organic molecule (benzochromen-6-one) is also given.

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“…As both the C 3 and the C 4 atoms were reported in the literature to be in the out-of-plane orientation, [27,30,33] mo- Figure 1. DQF-COSY and TOCSY spectra of 5b show no coupling between the hydrogen atoms of the lactone rings and the central macrocycle ring lecular mechanics calculations were performed to find the most stable conformations and the actual position of the plane of the lactone rings in 1a؊5a.…”

Section: Conformational and Nmr Studiesmentioning

confidence: 99%

Synthesis, Conformation and Equilibrium Study of New Piperazine and Azamacrocyclic Ligands with N-(Tetrahydro-2-oxofuran-3-yl) and N-[(Carboxy)(2-hydroxyethyl)methyl] Pendant Arms

et al. 2002

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Conformational analysis. Part 30.1 The conformational analysis of some lactones by the lanthanide induced shift (LIS) technique

Cited by 25 publications

References 31 publications

δ‐Galactonolactone: Synthesis, Isolation, and Comparative Structure and Stability Analysis of an Elusive Sugar Derivative

δ‐Galactonolactone: Synthesis, Isolation, and Comparative Structure and Stability Analysis of an Elusive Sugar Derivative

¹H chemical shifts in NMR. Part 21—Prediction of the ¹H chemical shifts of molecules containing the ester group: a modelling and ab initio investigation

Synthesis, Conformation and Equilibrium Study of New Piperazine and Azamacrocyclic Ligands with N-(Tetrahydro-2-oxofuran-3-yl) and N-[(Carboxy)(2-hydroxyethyl)methyl] Pendant Arms

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Conformational analysis. Part 30.1 The conformational analysis of some lactones by the lanthanide induced shift (LIS) technique

Cited by 25 publications

References 31 publications

δ‐Galactonolactone: Synthesis, Isolation, and Comparative Structure and Stability Analysis of an Elusive Sugar Derivative

δ‐Galactonolactone: Synthesis, Isolation, and Comparative Structure and Stability Analysis of an Elusive Sugar Derivative

1H chemical shifts in NMR. Part 21—Prediction of the 1H chemical shifts of molecules containing the ester group: a modelling and ab initio investigation

Synthesis, Conformation and Equilibrium Study of New Piperazine and Azamacrocyclic Ligands with N-(Tetrahydro-2-oxofuran-3-yl) and N-[(Carboxy)(2-hydroxyethyl)methyl] Pendant Arms

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¹H chemical shifts in NMR. Part 21—Prediction of the ¹H chemical shifts of molecules containing the ester group: a modelling and ab initio investigation