Absolute structures of C-glucosides of resveratrol oligomers from Shorea uliginosa

Two C-glucosides of resveratrol dimers (uliginoside A (1) and hemsleyanoloside B (2)) consisting of enantiomeric aglycones and two C-glucosides of resveratrol trimers (uliginosides B (3) and C (4)) consisting of diastereomeric aglycones were isolated from Shorea uliginosa (Dipterocarpaceae). These structures were elucidated by spectroscopic analysis including NMR experiments, and their absolute configurations were determined based on circular dichroism data. Resveratrol oligomers of C-glucosides with a 1,2-diaryldihydrobenzofuran ring are produced with specific biogenetic routes.     

4Z- and 4E-12-deoxydihydrokromycins,two naturally occurring kromycin aglycones of pikromycin from Streptomyces sp.

HPLC–UV guided isolation for the culture broth extract of the marine-derived bacterium Streptomyces sp. has led to the two 14-membered macrolides, 4Z- (1) and 4E-12-dehydroxykromycins (2). The chemical structures of compounds 1 and 2 were elucidated by spectral data, while the absolute stereochemistry of 1 and 2 were determined by application of circular dichroism (CD) and analysis of X-ray crystallographic data.     

Asymmetric Synthesis of (R)‐(−)‐Rhododendrol,the Aglycone of the Hepatoprotective Agent Rhododendrin

Abstract

Starting from 2,3‐O‐isopropylidene‐D‐glyceraldehyde (3) as chiral material, (R)‐(?)‐rhododendrol 2, the aglycone of the naturally occurring rhododendrin 1 was synthesized.     

Synthesis of pennogenin utilizing the intact skeleton of diosgenin

Pennogenin (1) is an aglycone of bioactive com-ponents of Chinese traditional medicine named Chonglou(Paris),[1] which belongs to C-17-hy- droxyl-steroidal sapogenin. It is well known that Chonglou as well as the related herbs containing pennogenin and its glycosides have been used as haemostatic agents in clinic. They also exhibit antibi-otic and antitumor activity[1,2]. With the demand amount of Chonglou as well as the related drugs increasing while the plant resource decreasing day by day…