Synthetic studies on the ophiobolane sesterterpenes: construction of an optically pure, advanced tricyclic intermediate for the synthesis of ceroplasteric acid

Abstract

Tropone has been transformed into an optically pure tricyclic system that could serve as an advanced intermediate in the synthesis of ceroplasteric acid. The sequence features a stereoselective Ireland ester enolate Claisen rearrangement followed by an intramolecular nitrite oxide cycloaddition for assembly of an ABC-ring precursor of the target molecule. Efforts to homologate the sevenmembered B ring to the requisite eight-membered system were unsuccessful.