Total Syntheses of Roseochelins A and B Using an Oxidative Decarboxylation Strategy

Roseochelins A and B are produced by <i>Phaeobacter inhibens</i> and proposed to arise from algal sinapic acid through combined enzymatic and nonenzymatic steps. We report concise, biomimetic total syntheses mirroring a revised biosynthetic pathway differing from earlier proposals in key oxidative and decarboxylative intermediates. Roseochelin A arises via spontaneous [4 + 2] dimerization of sinapic acid to thomasidioic acid, followed by metal-catalyzed oxidative decarboxylation. Roseochelin B is accessed by regioselective catechol formation, <i>ortho</i>-quinone-mediated thiomethylation, and late-stage metal- or photocatalyzed oxidative decarboxylation.