Pleurospiroketals A–E, Perhydrobenzannulated 5,5-Spiroketal Sesquiterpenes from the Edible Mushroom Pleurotus cornucopiae
摘要:
Five novel perhydrobenzannulated 5,5-spiroketal sesquiterpenes, namely, pleurospiroketals A-E (1-5), were isolated from the culture of the edible mushroom Pleurotus cornucopiae. Pleurospiroketals D (4) and E (5) were obtained as an isomeric mixture with a ratio of 5:4. Their structures were established by NMR, X-ray single-crystal diffraction, and CD data analysis. Pleurospiroketals A-E (1-5) are sesquiterpenoids with a unique benzannulated 5,5-spiroketal skeleton. Compounds 1-3 showed inhibitory activity against nitric oxide production in lipopolysaccharide-activated macrophages with IC50 values of 6.8, 12.6, and 20.8 mu M, respectively.
Asymmetric total synthesis of pleurospiroketals A and B
作者:Toyoharu Kobayashi、Konomi Tanaka、Masako Ishida、Natsumi Yamakita、Hideki Abe、Hisanaka Ito
DOI:10.1039/c8cc06185h
日期:——
The first asymmetric total synthesis of pleurospiroketals A and B has been accomplished in 16 steps from 5-methyl-5-hexenoic acid. Key features of the synthesis are the highly syn-selective Evans aldol reaction, ring-closing metathesis, highly diastereoselective dihydroxylation and acid-mediated spiroketalization.
Five novel perhydrobenzannulated 5,5-spiroketal sesquiterpenes, namely, pleurospiroketals A-E (1-5), were isolated from the culture of the edible mushroom Pleurotus cornucopiae. Pleurospiroketals D (4) and E (5) were obtained as an isomeric mixture with a ratio of 5:4. Their structures were established by NMR, X-ray single-crystal diffraction, and CD data analysis. Pleurospiroketals A-E (1-5) are sesquiterpenoids with a unique benzannulated 5,5-spiroketal skeleton. Compounds 1-3 showed inhibitory activity against nitric oxide production in lipopolysaccharide-activated macrophages with IC50 values of 6.8, 12.6, and 20.8 mu M, respectively.