6980-41-2Relevant academic research and scientific papers
Synthesis of 8-C-glucosylflavones
Kumazawa,Kimura,Matsuba,Sato,Onodera
, p. 183 - 193 (2007/10/03)
The syntheses of orientin, parkinsonin A, isoswertiajaponin, and parkinsonin B, which are 8-C-β-D-glucopyranosyl-3′,4′,5,7-tetrahydroxyflavone, 5-methyl orientin, 7-methyl orientin, and 5,7-dimethyl orientin, respectively, are reported herein. The C-glucosyl phloroacetophenone derivatives were obtained via a regio- and stereoselective O → C glycosyl rearrangement. Aldol condensation of the C-glucosyl phloroacetophenone derivatives with 3,4-bisbenzyloxybenzaldehyde afforded the corresponding C-glucosylchalcones. Construction of the flavone system by reaction with I2-Me2SO, followed by the elimination of the 5-benzyl protecting group in the flavone structure, yielded an orientin derivative and a isoswertiajaponin derivative. Methylation of the orientin derivatives with dimethyl sulfate afforded the parkinsonin A derivative, the isoswertiajaponin derivative, and the parkinsonin B derivative. Finally, hydrogenolysis of these C-glucosylflavone derivatives led to the four 8-C-glucosylflavones. The NMR spectra of these C-glucosylflavones showed a duplication of signals corresponding to a major rotamer, along with a minor one. Based on NOESY experiments in Me2SO at ambient temperature, they adopted conformations in which the H-2″ and H-4″ protons in the glucose moiety were oriented toward the B-ring in the flavone structure.
