178101-87-6Relevant articles and documents
The economical synthesis of [2'-(13)C, 1,3-(15)N2]uridine; preliminary conformational studies by solid state NMR.
Patching, Simon G,Middleton, David A,Henderson, Peter J F,Herbert, Richard B
, p. 2057 - 2062 (2003)
The synthesis of [2'-(13)C, 1,3-(15)N2]uridine 11 was achieved as follows. An epimeric mixture of D-[1-(13)C]ribose 3 and D-[1-(13)C]arabinose 4 was obtained in excellent yield by condensation of K13CN with D-erythrose 2 using a modification of the Kiliani-Fischer synthesis. Efficient separation of the two aldose epimers was pivotally achieved by a novel ion-exchange (Sm3+) chromatography method. D-[2-(13)C]Ribose 5 was obtained from D-[1-(13)C]arabinose 4 using a Ni(II) diamine complex (nickel chloride plus TEMED). Combination of these procedures in a general cycling manner can lead to the very efficient preparation of specifically labelled 13C-monosaccharides of particular chirality. 15N-labelling was introduced in the preparation of [2'-(13)C, 1,3-(15)N2]uridine 11 via [15N2]urea. Cross polarisation magic angle spinning (CP-MAS) solid-state NMR experiments using rotational echo double resonance (REDOR) were carried out on crystals of the labelled uridine to show that the inter-atomic distance between C-2' and N-1 is closely similar to that calculated from X-ray crystallographic data. The REDOR method will be used now to determine the conformation of bound substrates in the bacterial nucleoside transporters NupC and NupG.
Successive C1-C2 bond cleavage: The mechanism of vanadium(v)-catalyzed aerobic oxidation of d-glucose to formic acid in aqueous solution
Niu, Muge,Hou, Yucui,Wu, Weize,Ren, Shuhang,Yang, Ru
, p. 17942 - 17951 (2018/07/14)
Vanadium(v)-catalyzed aerobic oxidation in aqueous solution shows high selectivity in the field of C-C bond cleavage of carbohydrates for chemicals with less carbon atoms. However, the pathway of C-C bond cleavage from carbohydrates and the conversion mechanism are unclear. In this work, we studied the pathway and the mechanism of d-glucose oxidation to formic acid (FA) in NaVO3-H2SO4 aqueous solution using isotope-labeled glucoses as substrates. d-Glucose is first transformed to FA and d-arabinose via C1-C2 bond cleavage. d-Arabinose undergoes similar C1-C2 bond cleavage to form FA and the corresponding d-erythrose, which can be further degraded by C1-C2 bond cleavage. Dimerization and aldol condensation between carbohydrates can also proceed to make the reaction a much more complicated mixture. However, the fundamental reaction, C1-C2 bond cleavage, can drive all the intermediates to form the common product FA. Based on the detected intermediates, isotope-labelling experiments, the kinetic isotope effect study and kinetic analysis, this mechanism is proposed. d-Glucose first reacts with a vanadium(v) species to form a five-membered-ring complex. Then, electron transfer occurs and the C1-C2 bond weakens, followed by C1-C2 bond cleavage (with no C-H bond cleavage), to generate the H3COO-vanadium(iv) complex and d-arabinose. FA is generated from H3COO that is oxidized by another vanadium(v) species. The reduced vanadium species is oxidized by O2 to regenerate to its oxidation state. This finding will provide a deeper insight into the process of C-C bond cleavage of carbohydrates for chemical synthesis and provide guidance for screening and synthesizing new highly-efficient catalyst systems for FA production.
Phosphate-catalyzed degradation of d-glucosone in aqueous solution is accompanied by C1-C2 transposition
Zhang, Wenhui,Serianni, Anthony S.
, p. 11511 - 11524 (2012/08/28)
Pathways in the degradation of the C6 1,2-dicarbonyl sugar (osone) d-glucosone 2 (d-arabino-hexos-2-ulose) in aqueous phosphate buffer at pH 7.5 and 37 °C have been investigated by 13C and 1H NMR spectroscopy with the use of singly and doubly 13C-labeled isotopomers of 2. Unlike its 3-deoxy analogue, 3-deoxy-d-glucosone (3-deoxy-d-erythro-hexos-2-ulose) (1), 2 does not degrade via a 1,2-hydrogen shift mechanism but instead initially undergoes C1-C2 bond cleavage to yield d-ribulose 3 and formate. The latter bond cleavage occurs via a 1,3-dicarbonyl intermediate initially produced by enolization at C3 of 2. However, a careful monitoring of the fates of the sketetal carbons of 2 during its conversion to 3 revealed unexpectedly that C1-C2 bond cleavage is accompanied by C1-C2 transposition in about 1 out of every 10 transformations. Furthermore, the degradation of 2 is catalyzed by inorganic phosphate (Pi), and by the Pi-surrogate, arsenate. C1-C2 transposition was also observed during the degradation of the C5 osone, d-xylosone (d-threo-pentose-2- ulose), showing that this transposition may be a common feature in the breakdown of 1,2-dicarbonyl sugars bearing an hydroxyl group at C3. Mechanisms involving the reversible formation of phosphate adducts to 2 are proposed to explain the mode of Pi catalysis and the C1-C2 transposition. These findings suggest that the breakdown of 2 in vivo is probably catalyzed by Pi and likely involves C1-C2 transposition.
Reaction pathways of glucose oxidation by ozone under acidic conditions
Marcq, Olivier,Barbe, Jean-Michel,Trichet, Alain,Guilard, Roger
experimental part, p. 1303 - 1310 (2009/12/01)
The ozonation of d-glucose-1-13C, 2-13C, and 6-13C was carried out at pH 2.5 in a semi-batch reactor at room temperature. The products present in the liquid phase were analyzed by GC-MS, HPAEC-PAD, and 13C NMR s
Analysis of metabolic pathways via quantitative prediction of isotope labeling patterns: A retrobiosynthetic 13C NMR study on the monoterpene loganin
Eichinger, Dietmar,Bacher, Adelbert,Zenk, Meinhart H.,Eisenreich, Wolfgang
, p. 223 - 236 (2007/10/03)
The monoterpene loganin serves as a precursor in the biosynthetic pathways of numerous indole alkaloids. In contrast to earlier studies, we present evidence that the biosynthesis of loganin in Rauwolfia serpentina cells proceeds mainly via the deoxyxylulose pathway and not by the mevalonate pathway. This conclusion is based on experiments using a R. serpentina cell culture supplied with 13C-labeled samples of glucose, ribose/ribulose, pyruvate or glycerol. Loganin was isolated from biomass, and the hydrolysis of cellular protein afforded amino acids. The isolated metabolites were analyzed by NMR spectroscopy. The 13C-labeling patterns of isolated amino acids were then used to reconstruct the labeling patterns of phosphoenol pyruvate, pyruvate and acetyl CoA. These labeling patterns were subsequently used to predict labeling patterns for dimethylallyl pyrophosphate and isopentenyl pyrophosphate via the mevalonate and deoxyxylulose pathway, respectively. The observed labeling patterns of the terpenoid moieties in loganin were in excellent agreement with the deoxyxylulose prediction. The minor incorporation of mevalonate into loganin observed in earlier studies can be attributed to metabolite exchange between the two terpenoid pathways. The possibility of crosstalk between the two pathways in plants and plant cell cultures stresses the need for a quantitative analysis of general carbon metabolism in order to determine the partitioning between the mevalonate and deoxyxylulose pathway. The present study shows that a wide variety of general metabolic precursors can fulfill this task in conjunction with the retrobiosynthetic concept.
Two-bond 13C-13C spin-coupling constants in carbohydrates: New measurements of coupling signs
Zhao, Shikai,Bondo, Gail,Zajicek, Jaroslav,Serianni, Anthony S.
, p. 145 - 152 (2007/10/03)
D-(1,3,6-13C3)Allose (1), (13C)methyl α-D-(1,2-13C2)glucopyranoside (2) and (13C)methyl β-D-(1,2-13C2)glucopyranoside (3) were synthesized and used to establish the signs of their constituent 2J(CCC) or 2J(COC) values (2J(C1,C3) in the α-pyranose of 1 (15), and 2J(C1,CH3) in 2 and 3). Compounds 2, 3 and 15 contain three mutually coupled labeled carbons, thus creating a three-spin system from which crosspeak displacements in 13C-13C COSY-45 spectra were used to determine coupling signs. In all compounds, at least one 3J(CC) value was present as an internal reference: 3J(C2,CH3 in 2 and 3, and 3J(C1,C6) and 3J(C3,C6) in 15. 2J(C1,CH3), in 2 and 3, and 2J(C1,C3) in 15, were found to be negative, thus providing experimental confirmation of the sign predictions made via the projection resultant rule described recently.
SYNTHESIS OF L-(4-2H)ERYTHROSE, L-(1-13C, 5-2H)ARABINOSE AND L-(2-13C, 5-2H)ARABINOSE AND IDENTIFICATION OF THE INTERMEDIATES BY 2H AND 13C-N.M.R. SPECTROSCOPY
Han, Chung H.,Sillerud, Laurel O.
, p. 247 - 264 (2007/10/02)
L-(1-13C, 5-2H)Arabinose (6D) and L-(2-13C, 5-2H)arabinose (8D) have been synthesized by degradation of 2,3-O-isopropylidene-β-L-rhamnofuranose (2) to L-(4-2H)erythrose (5β, 5αD), with subsequent chain elongation to 6D plus L-(1-13C, 5-2H)ribose (7D), the latter being converted into 8D.Intermediates were identified by complete assignment of the 13C chemical shifts employing carbon-carbon and carbon-deuterium coupling constants, deuteration shifts, differential isotope-shifts, and deuterium spectra.The anomeric carbon atoms of 2 and 2,3-O-isopropylidene-L-(1-2H)erythrose (4D) gave only single 13C resonances, suggesting that these two compounds exists in only one major anomeric configuration, clarifying previously reported work.The synthesis of 2,3-O-isopropylidene-L-(1-2H)rhamnitol (3D) facilitated the assignment of the signals in the 13C spectra of the nondeuterated analog.Specific deuterium-enrichment and the observed carbon-deuterium coupling (1JC,D ca. 22 Hz) not only served to identify the deuterated carbon atom unambiguously in 3 but also permitted assignment of closely spaced resonances.The deuterium spectrum of 2,3-O-isopropylidene-L-(4-2H)erythrofuranose (4D) showed only a single resonance, indicating preponderance of one anomer, in accord with the observation of a single C-1 resonance in the 13C spectrum.
Paramolybdate anion-exchange resin, an improved catalyst for the C-1-C-2 rearrangement and 2-epimerization of aldoses.
Clark Jr.,Hayes,Barker
, p. 263 - 270 (2007/10/02)
Aqueous solutions of molybdate at 90 degrees bring about the inversion of the C-1-C-2 fragment of aldoses having four or more carbon atoms, generating thermodynamically equilibrated mixtures of the starting aldose and its 2-epimer. In some cases, notably with the aldopentoses, substantial proportions of the 3-epimers are produced, as well as 2-epimers that have not undergone inversion of the C-1-C-2 fragment. These side-reactions can be controlled by using the paramolybdate form of an anion-exchange resin (AG MP-1) together with the formate form of the same resin. The latter acts to scavenge unbound molybdate and paramolybdate anions that appear to be responsible for the side reactions.
