Discovery of Hypoiodite-Mediated Aminyl Radical Cyclization Lacking a Nitrogen Radical-Stabilizing Group: Application to Synthesis of an Oxazaspiroketal-Containing Cephalostatin Analog

Synthesis of an oxazaspiroketal-containing bissteroidal pyrazine is described. The key transformation of this synthesis involves stereoselective formation of oxazaspiroketal via aminyl-radical cyclization of primary amine lacking a radical-stabilizing group by Suárez hypoiodite oxidation.