Key steps in the convergent enantioselective synthesis of the cytotoxic natural product cylindramide are tandem Michael addn./electrophilic trapping reactions, Sonogashira coupling, Julia-Kocienski olefination, and macrocyclization. For example, the Sonogashira coupling of pentalene I with iodoacrylate II followed by Julia-Kocienski olefination with sulfone III gave an intermediate which underwent macrocyclization. Formation of the tetramic acid completed the synthesis.
Qian Wang, Jieping Zhu, Jian Cao, Guihua Chen
Xile Hu, Runze Mao, Srikrishna Bera