Jatrophane Diterpenes: Preparation of the Western Fragment of Pl-3

Jatrophane diterpenes are structurally intriguing natural products with promising biological properties. Herein, the synthesis of the western fragment of the Euphorbiaceae constituent Pl-3 starting from (1R,5S)-bicyclo[3.2.0]hept- 2-en-6-one is described. Key steps in the sequence include a Baeyer-Villiger oxidation, an iodolactonization reaction, and the installation of the northern side chain through the addition of a lithiated vinyl bromide. The overall efficiency of the route is increased by taking advantage of latent symmetry. The synthesis of the western fragment of Pl-3 is developed by taking advantage of the latent symmetry in an intermediate; both enantiomers are thus converted into the desired substrate. Key steps of the synthesis include a Baeyer-Villiger oxidation, an iodolactonization reaction, and the addition of a vinyllithium species to the completed cyclopentane moiety of the natural product.