Synthesis of (1Z)-deacylcnicin

Abstract

Cnicin is a germacranolide sesquiterpene lactone with a 10-membered ring, two internal olefins, two exo olefins, and an ester side chain. The natural product is a potent inhibitor of Trypanosoma brucei, which causes human African trypanosomiasis. This study examined the synthesis of cnicin via the Evans syn aldol reaction, the indium-promoted diastereoselective Barbier reaction, and ring-closing metathesis (RCM). While RCM did not afford natural (1E)-form as the major product, the synthesis of (1Z)-deacylcnicin was achieved.