Diastereoselective Synthesis of Cyclic and Spirocyclic Quaternary Carbons via Iron-Catalyzed Ring Contraction of Cyclic Ketones: A Formal Synthesis of Perhydrohistrionicotoxin

The iron-catalyzed hydrogen atom transfer (HAT)-initiated Dowd-Beckwith rearrangement presents a new approach for synthesizing cyclic and spirocyclic quaternary carbons from readily available β-keto esters and cyclic diketones with high yields. This reaction proceeds in a stereocontrolled manner, enabling the formation of synthetically valuable cyclic ketones with two contiguous stereocenters, including quaternary centers. This transformation introduces an innovative bond disconnection strategy for ring-contraction reactions. Additionally, a short formal synthesis of perhydrohistrionicotoxin was efficiently achieved using this methodology.