An improved synthesis of the [5.6.7]-tricyclic core of cyrneine B and glaucopine C

Abstract

A new route for the synthesis of the [5.6.7]-tricyclic core structure of cyrneine B and glaucopine C is presented. The key transformations included an efficient Suzuki cross-coupling of the densely substituted cyclopentenyl triflate with cyclic vinylboronate and a highly regio- and stereoselective intramolecular deconjugative alkylation. The synthetic route allowed for the construction of the [5.6.7]-tricyclic core within a 16-step linear sequence from the commercially available 2-methylcyclopentanone, which is five steps shorter than the first generation route as reported previously by us.