Stereoselective total synthesis of (+)-radicamine B via anti,syn,syn-oxazine

Abstract

The stereoselective total synthesis of (+)-radicamine B was achieved using commercially available d-4-hydroxy-phenylglycine via chiral 1,3-oxazine, which has been applied to synthesis of amino polyols such as DAB-1, d-fagomine, and phytosphingosines. The key steps in this strategy were the palladium(0)-catalyzed stereoselective intramolecular oxazine formation, an extension of the chirality of anti,syn-oxazine with Lewis acid and vinylmagnesium bromide, and pyrrolidine ring formation via hydrogenation reaction. The chiral extension is also applicable to other chiral 1,3-oxazine derived from d-4-hydroxy-phenylglycine.