Determination of the Anomeric Configuration of C-Nucleosides by¹H and¹³C NMR Spectroscopy

Circular dichroism as a reliable tool for anomeric assignment of glycosyl‐2‐phenyl‐2H‐1,2,3‐triazole C‐nucleoside analogs. A rule for prediction of their anomeric configuration

“…The anomeric configuration can be determined by 1 H NMR spectroscopy. 13 Having the two anomers on hand, only the anomer having low coupling constant value J1 0 -OH and 3 0 -OH in trans relationship. In addition, the chemical shift difference between the two anomers, is some times not large enough to be useful diagnostic.…”

“…CD measurements were recorded for solutions in methanol on Jasco-J 500 H, and Jasco 720WI spectropolarimeters at concentrations 0.25-0.3 mg/ml methanol (0.2 ml microcell). 1 H NMR spectra were recorded with Jeol JNM ECA 500 MHz DELTA 2 NMR spectrometer, 13 C NMR spectra were recorded with Jeol/JNM ECA 500 at 125 MHz. Nuclear Overhauser effect (NOE) experiments were obtained using DPFGSE Program.…”

“…8 Acetylation of Compounds (7)(8)(9)(10) According to general procedure, compounds (7)(8)(9)(10) were acetylated with a mixture of pyridine-acetic anhydride 1:1, kept overnight, evaporated till dryness, and traces of pyridine were removed by spin coevaporation with toluene. The residue was chromatographed on a short column, eluted with solvent D. For 1 H NMR spectra see Table 1, for 13 C NMR spectra see Table 2, and for MS spectra (selected ions) see Table 3.…”

Vitamin B12 and α-ribonucleosides

“…The methyl proton chemical shifts and chemical shift separation for the endo-and exo-methyl groups of the isopropylidene in protected nucleosides, have been extensively used to determine the anomeric configuration of nucleosides. 81, 82 Imbach 83 suggests that the difference in the 1 H chemical shifts between the two methyl signals of the isopropylidene group, Δδ, can be used to distinguish between the α-and β-anomers such that 0.18<Δδ<0.23 for the β-anomers and 0<Δδ<0.10 for the α-anomers (Fig. 9 α-imidazole nucleoside).…”

Computational Study of some Double Headed Acyclo-C-Nucleosides

“…[3][4][5][6][7][8][9][10] Indeed, the modern structural features of nucleosides are somewhat different from those present in poly-ribonucleotides RNA and DNA, [11] by means of variations in sugar, heterocyclic moieties and the various modes of attachments between the two major components (sugar and heterocycle). The literature of the new kinds of nucleosides is increasing and a lot of variations and kinds of nucleosides with dinuclear nucleosides [12,13] and others were also reported.…”