| Abstract: | Summary A comparative analysis of the PMR spectra of a number of flavonoid O-arabinosides and O-xylosides and of their full acetates and TMS ethers has been made which has permitted the determination of the conformations of the pentoses and of the glycosidic bonds. The region of the signals of the protons at C-5 in the spectra of the full acetates is diagnostic for determining the size of the oxide ring of a pentose residue.Polystachoside and guaiaverin have been shown to be identical (quercetin 3-O- -L-arabinopyranoside). Inversion of the conformation of the pyranose ring of the arabinose residue has been detected for the TMS ethers of guaiaverin and polystachoside.All-Union Scientific-Research Institute of Medicinal Plants, Moscow. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 21–34, January–February, 1979. |
