quaternary centers were synthesized in moderate to good yields by treatment of various hexahydro-3,4-dioxa-8a-aza-as-indacen-2-ones with m-CPBA under basic conditions through a tandem Cope elimination/1,3-dipolar cycloadditionreaction sequence, followed by N-O cleavage and lactam ring cyclization.
Total Synthesis of Indolizidine Alkaloids (-)-167B, (-)-209I, and (-)-223A by Using a Common Tricyclic Lactone
作者:Yu-Jang Li、Chung-Chien Hou、Kuei-Chen Chang
DOI:10.1002/ejoc.201500028
日期:2015.3
Highly stereocontrolled totalsynthesis of dart frog indolizidine alkaloids (–)-167B, (–)-209I, and (–)-223A was accomplished, with a common tricyclic lactone intermediate as the starting compound, in overall yields of 17 %, 14 %, and 17 %, respectively. The C7–C8 bond of the 167B, without a C8 chiral substituent, was formed through ring closure metathesis followed by hydrogenation. In 209I and 223A