Examination of the molecular properties of <scp>D</scp>-fructose and <scp>L</scp>-sorbose by <i>ab</i><i>initio</i> LCAO-MO calculations

Szarek, Walter A.; Korppi-Tommola, Sirkka-Liisa; Martin, Olivier R.; Smith, Vedene H.

doi:10.1139/v84-257

Cited by 10 publications

(5 citation statements)

References 7 publications

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“…This approach seems to lend support to Birch's proposal since it was found that the zone of greatest hydrophilicity in P-D-fructopyranose was centered around the 4-OH group, thus possibly making this group essential for sweetness. This is also consistent with our prediction that the 0 -4 atom would be the most attractive site for protonation (9). Of relevance are also the observations that both the 6-thio-(15) and the 6-carba-(16) analogs of P-Dfructopyranose are intensely sweet, presumably as a result of the expansion of the hydrophobic region of the molecule (2).…”

supporting

confidence: 90%

Structure–sweetness relationships for fructose analogs. Part III. 3-Deoxy-D-erythro-hexulose (3-deoxy-D-fructose): composition in solution and evaluation of sweetness

Szarek¹,

Rafka²,

Yang³

et al. 1995

Can. J. Chem.

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Abstract:As part of continuing studies on the structural features responsible for the intense sweetness of D-fructose, 3-deoxy-D-erythro-hexulose (3-deoxy-D-fructose, 1) was prepared, its solution composition was determined, and its taste was evaluated. In aqueous solution, 3-deoxy-D-fructose exists as a complex mixture of five tautomeric forms in which the P-D-pyranose form is preponderant (52.5% at 22OC) and the a-D-pyranose form is the least abundant (5%). Quite remarkable is the behavior of the open-chain keto form of 1: its content increases from 7.5% at 22"C, to 36% at 82OC, and to 47% at 97OC, making this form the preponderant one at high temperatures. 3-Deoxy-D-fructose was found to be sweet, albeit probably not as sweet as D-fructose. The hydroxyl group at C-3 is thus not an essential function of the glycophore of D-fructose. The significance of this result is discussed in relation to the evidence already available and the divergent theories that have been proposed to explain the origin of the sweet taste of D-fructose.Key words: 3-deoxy-D-erythro-hexulose (3-deoxy-D-fructose), sweetness, solution composition.Resume : La poursuite d'ttudes sur les attributs structuraux responsables pour la douceur intense du D-fructose nous a conduit B prCparer le 3-dCsoxy-D-Prythro-hexulose (3-dCsoxy-D-fructose, I), B determiner sa composition en solution et h Cvaluer son gotit. En solution aqueuse, le 3-dCsoxy-D-fructose existe sous forme d'un mClange complexe de cinq formes tautomkres dans lequel la forme P-D-pyranose est prtpondtrante (52.5% j. 22°C) et la forme a-D-pyranose est la moins abondante (5%). Le comportement de la forme a chalne ouverte ce'to est tout-i-fait remarquable : prtsente i 7.5% i 22"C, sa concentration augmente i 36% i 82°C et i 47% B 97"C, ce qui en fait la forme la plus abondante i haute tempkrature. Le 3-dCsoxy-D-fructose est doux, cependant probablement pas aussi doux que le D-fructose. Le groupement hydroxyle en C-3 apparait ainsi ne pas &tre une fonction essentielle du glycophore du D-fructose. L'importance de ce rtsultat est discutC en relation avec les donnCes dCji disponibles et les thCories divergentes qui ont Ct C proposCes pour expliquer l'origine de la douceur du D-fructose.Mots clPs : 3-dtsoxy-D-e'rythro-hexulose (3-dtsoxy-D-fructose), caractkre sucrt, composition d'une solution.The origin of the intense sweetness of D-fructose, the sweetest of the natural sugars (I), has been the object of much debate (2). While the lipophilic component X of the presumed tripartite AH-B-X glycophore (3) can be attributed to one of the methylene groups (2), the assignment of the hydrogen bond donor (AH) and acceptor (B)-couple remains unresolved. As part of continuing studies on deoxy ketohexoses designed to probe the role of individual hydroxyl groups in the glycophore of D-fructose, we have already shown (4) that the 5-OH group is not essential for the sweet response since 5-deoxy-D-threohexulose (5-deoxy-D-fructose) is nearly as sweet as D-fructose. We have now completed studies on 3-and 4-deoxy...

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supporting

confidence: 90%

Structure–sweetness relationships for fructose analogs. Part III. 3-Deoxy-D-erythro-hexulose (3-deoxy-D-fructose): composition in solution and evaluation of sweetness

Szarek¹,

Rafka²,

Yang³

et al. 1995

Can. J. Chem.

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“…The simplest carbohydrates are monosaccharides, whose low-energy conformations can be reliably predicted by suitably chosen computational methods . Theoretical conformational studies appeared for glucose, − fructose, − ribose, , deoxyribose, , and erythrose. − The availability of high-accuracy structural and spectroscopic data for gas-phase C 4 and C 5 monosaccharides is a prerequisite for their possible detection in space. − …”

Section: Introductionmentioning

confidence: 99%

Tautomers of Gas-Phase Erythrose and Their Interconversion Reactions: Insights from High-Level ab Initio Study

Szczepaniak

Moc

2015

J. Phys. Chem. A

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D-Erythrose is a C4 monosaccharide with a biological and potential astrobiological relevance. We have investigated low-energy structures of d-erythrose and their interconversion in the gas phase with the highest-level calculations up-to-date. We have identified a number of structurally distinct furanose and open-chain isomers and predicted α ↔ α and β ↔ β furanose interconversion pathways involving the O-H rotamers. We have estimated relative Gibbs free energies of the erythrose species based on the CCSD(T)/aug-cc-pVTZ electronic energies and MP2/aug-cc-pVTZ vibrational frequencies. By using natural bond orbital theory we have also quantified a stabilization of erythrose conformers and interconversion transition states by intramolecular H-bonds.

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“…To prevent the sugar's thermal decomposition, 30 the two groups used high-speed laser evaporation which was combined with microwave (MW) spectroscopy to measure rotational In addition to the recent MW spectroscopic search of D-fructose, 7,29 there were (mostly) low-level theoretical studies on this sugar in the gas phase which will now be briefly reviewed. The early ab initio RHF/STO-3G calculations by Szarek et al 31,32 assumed the crystal structure as input geometry. These authors also reported semiempirical AM1 optimized structures and energies of β-D-fructopyranose.…”

Section: Introductionmentioning

confidence: 99%

Cyclic and Acyclic Fructose Conformers in the Gas Phase: A Large-Scale Second-Order Perturbation Theory Study

Szczepaniak

Moc

2014

J. Phys. Chem. A

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We performed large-scale second-order perturbation theory gas-phase calculations to study about five hundred structures of D-fructose. The two lowest energy fructose structures identified are β-pyranoses possessing (2)C5 chair, with ΔG(298 K) of 6 kJ/mol, differing in orientation of the equatorially positioned hydroxymethyl group, gt and g'g, where the gt rotamer is the global minimum, consistent with the recent microwave spectroscopy study. We have found that interconversions from the fructose global minimum to the second and third most stable β-pyranose rotamers involve the energy barriers of ca. 30 kJ/mol. Among numerous fructofuranose conformers discovered (about 250), a pair of the ((3)T2) α- and (E3) β-anomers are energetically most preferred and lie at least 12 kJ/mol above the global minimum. We also found that the fructose open-chain structures lie significantly higher in energy than the most stable cyclic species. The commonly used M06-2X density functional performs well compared to MP2 and G4 theory at identifying the low-energy fructose minima, including the global one, and at reproducing their intramolecular H-bond geometric parameters. The lowest-energy gas-phase pyranose and furanose structures of fructose benefit from stabilization due to the cooperative or quasi-linear H-bonding and both endo and exo anomeric effects.

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Examination of the molecular properties of D-fructose and L-sorbose by abinitio LCAO-MO calculations

Cited by 10 publications

References 7 publications

Structure–sweetness relationships for fructose analogs. Part III. 3-Deoxy-D-erythro-hexulose (3-deoxy-D-fructose): composition in solution and evaluation of sweetness

Structure–sweetness relationships for fructose analogs. Part III. 3-Deoxy-D-erythro-hexulose (3-deoxy-D-fructose): composition in solution and evaluation of sweetness

Tautomers of Gas-Phase Erythrose and Their Interconversion Reactions: Insights from High-Level ab Initio Study

Cyclic and Acyclic Fructose Conformers in the Gas Phase: A Large-Scale Second-Order Perturbation Theory Study

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