Unified Synthesis of Eudesmanolides, Combining Biomimetic Strategies with Homogeneous Catalysis and Free-Radical Chemistry
journal contributionposted on 09.05.2003, 00:00 by Alejandro F. Barrero, Antonio Rosales, Juan M. Cuerva, J. Enrique Oltra
A general procedure for the synthesis of both 12,6- and 12,8-eudesmanolides has been developed. The key step is the titanocene-catalyzed radical cyclization of accessible epoxygermacrolides. The novel reagent 2,4,6-trimethyl-1-trimethylsilylpyridinium chloride, both compatible with oxiranes and capable of regenerating Cp2TiCl2 from Cp2Ti(Cl)H and Cp2Ti(Cl)OAc, played an important role in the catalytic cycle leading to exocyclic alkenes.