Enantioselective formal total syntheses of didehydrostemofoline and isodidehydrostemofoline through a catalytic dipolar cycloaddition cascade

Sweet to the core: Enantioselective formal total syntheses of the title compounds were accomplished in 24 steps from 2-deoxy-D-ribose. The synthesis features a novel cascade of reactions culminating in an intramolecular dipolar cycloaddition to form the tricyclic core of the stemofoline alkaloids from an acyclic diazo imine intermediate.