Synthesizing Molecules with Linear Tricyclic 5/5/5 and 6/5/5 Skeletons via [5 + 2 + 1]/Ene Strategy.

Report here is the development of a [5 + 2 + 1]/ene strategy for the synthesis of molecules with linear tricyclic 5/5/5 and 6/5/5 skeletons widely found in natural products. The first step of this strategy is applying a Rh-catalyzed [5 + 2 + 1] reaction of ene-vinylcyclopropanes and CO to synthesize 5/8 and 6/8 bicyclic compounds, which can then be transformed to the final target molecules by an InCl3-catalyzed ene reaction.