Cp2TiCl-Mediated Reductive Cyclization: Total Synthesis of Pestalotiolactone A, Myrotheciumone A, and Scabrol A

Abstract

The first stereoselective total syntheses of fungal secondary metabolites monoterpenoid (+)-pestalotiolactone A, meroterpenoid (−)-myrotheciumone A, and iridoid lactone (+)-scabrol A have been accomplished in an expedient unified approach starting from d-(+)-malic acid employing an epoxide opening-radical cyclization protocol initiated by Cp2Ti(III)Cl as a key step to assemble the core bicyclic lactone moieties of these molecules with complete diastereoselective control. Finally, the deoxygenation and methylation delivered the target natural products.