Substituent effects in the transannular cyclizations of germacranes. Synthesis of 6-epi-costunolide and five natural steiractinolides
作者:Redouan Azarken、Francisco M. Guerra、F. Javier Moreno-Dorado、Zacarías D. Jorge、Guillermo M. Massanet
DOI:10.1016/j.tet.2008.09.017
日期:2008.11
The occurrence and orientation of substituents in the 10-membered ring characteristic of germacranes is determinant in the stereochemical outcome of the acid-promotedtransannularcyclization of these metabolites. An explanation of the synthesis of eudesmanolides and guaianolides produced by the Umbelliferae family of plants is advanced. The syntheses of the natural products 6-epi-costunolide and five
Parthenolide showed extensive bioactivities including selective eradication of AML stem cells. Herein we report protection-free semisyntheses of parthenolide and its cyclopropyl analogue (compound 10) from the abundant natural product costunolide with an overall yield of 55 and 60%, respectively. Compound 10 was more stable than parthenolide, and it maintained comparable activities against AML cell lines and AML stem cells. Therefore, compound 10 might be a superior small molecule than parthenolide as a tool for investigation of cancer stem cell biology.