Total Synthesis of (+)-Cladantholide and (-)-Estafiatin: 5-Exo,7-Endo Radical Cyclization Strategy for the Construction of Guaianolide Skeleton

摘要

In each of the present studies, a cyclopentanoid intermediate was utilized in the preparation of the guaianolide skeleton by fusing a seven-membered carbocycle and a lactone moiety. Remarkably, the 5-exo, 7-endo tandem radical cyclizations were found to be highly efficient under reductive or oxidative radical- generating conditions solving at the same time the difficult stereochemical problems in forming functionalized seven- membered carbocycles.