The novel flavan-3-ol, (2R,3S)-guibourtinidol and its diastereomers
摘要:
The novel (2R,3S)-guibourtinidol, representing the first flavan-3-ol with 4',7-dihydroxy phenolic substitution pattern, was identified in the heartwood of Cassia abbreviata. Asymmetric dihydroxylation of (E)-1-(4'-O-methoxymethylphenyl)-3-(2 ",4 " di- O-methoxymethylphenyl)-propene with AD-mix-alpha or AD-mix-beta and subsequent acid-catalyzed cyclization afforded the four free phenolic guibourtinidol diastereomers, essentially enantiopure and in good yield. (C) 1999 Elsevier Science Ltd. All rights reserved.