Total Syntheses of (±)-cis-Trikentrin A and (±)-cis-Trikentrin B via Electrocyclic Ring Closures of 2,3-Divinylpyrrolines

A convergent and versatile strategy for the diastereoselective syntheses of (±)-cis-trikentrin A and B in 10 and 12 steps, respectively, from commercially available N-BOC-2-pyrrolidinone is described. The key step in each of the total syntheses is the construction of the central benzene ring via a facile 6π-electrocyclic ring closure of an appropriately substituted 2,3-divinylpyrroline, in turn, readily available by a Stille coupling reaction.