The first totalsynthesis of a marine natural product, exigurin, has been accomplished in 13 steps starting from (+)-menthone. The key intermediate (-)-10-epi-axisonitrile-3 was prepared by stereoselective intramolecular cyclopropanation followed by a cyclopropane ring opening reaction by the azide anion. The bioinspired Ugi reaction of (-)-10-epi-axisonitrile-3, formaldehyde, sarcosine and methanol
(+)-Exiguamide is a nitrogen-containing spirocyclic sesquiterpeneisolatedfrom the marine sponge Geodia exigua. This study aims to report the first synthesis of both enantiomers of exiguamide, featuring the stereoselective intramolecular cyclopropanation and stereoselective homoconjugate addition of azide to cyclopropyl ketone as the key steps.
New spirocyclic sesquiterpenes from the marine sponge Geodia exigua
作者:Mylene M Uy、Shinji Ohta、Mihoko Yanai、Emi Ohta、Toshifumi Hirata、Susumu Ikegami
DOI:10.1016/s0040-4020(02)01619-8
日期:2003.2
Three new spirocyclic sesquiterpenes designated exiguamide (1), exicarbamate (2) and exigurin (3), together with (−)-10-epi-axisonitrile-3 (4), have been isolated from the marinesponge Geodia exigua. All four compounds possess the spiro[4.5]decene skeleton and their structures were determined on the basis of spectroscopic data. The structure of 1 was confirmed by X-ray crystallographic analysis and