Protection-Group-Free Semisyntheses of Parthenolide and Its Cyclopropyl Analogue

Parthenolide showed extensive bioactivities including selective eradication of AML stem cells. Herein we report protection-free semisyntheses of parthenolide and its cyclopropyl analogue (compound <b>10</b>) from the abundant natural product costunolide with an overall yield of 55 and 60%, respectively. Compound <b>10</b> was more stable than parthenolide, and it maintained comparable activities against AML cell lines and AML stem cells. Therefore, compound <b>10</b> might be a superior small molecule than parthenolide as a tool for investigation of cancer stem cell biology