Diastereoselective Synthesis of the Hydroperoxide-Keto Form of (±)-Steenkrotin B.

A diastereoselective approach for the synthesis of the hydroperoxide-keto form of (±)-steenkrotin B (2') is described. The key features of the strategy involve a Diels-Alder cycloaddition, a titanium(III)-catalyzed reductive annulation, and a regio- and diastereoselective hydroperoxidation.