Abstract: The synthesis of fomannosin, a toxic fungal metabolite with a unique methylenecyclobutene structure, is approached in two different ways, making use of rigid tricyclic intermediates to control the configuration at two crucial chiral centers. The first approach was carried through the formation of the cyclobutane ring, using cycloaddition of ethoxyacetylene to a ketene. The stereoselectivity was disappointing, and that strategy ...
