Iodine(III)-Promoted Ring Contractive Cyanation of Exocyclic β-Enaminones for the Synthesis of Cyanocyclopentanones

A highly efficient hypervalent iodine-promoted regiocontrolled ring contractive cyanation (RCC) reaction of exocyclic β-enaminones for the synthesis of cyanocyclopentanone (CCP) was demonstrated at ambient temperature with a wide substrate scope. The methodology offers a facile technique to construct an amino carbonitrile-containing quaternary stereocenter at the α-position of cyclopentanone in good yields. The sequence of substrate addition that can facilitate the reaction to follow different pathways (free radical/non-radical) to afford the same final product was critically investigated.