Synthesis of Nitrile Bearing Acyclic Quaternary Centers through Co(III)‐Catalyzed Sequential C−H Bond Addition to Dienes and N‐Cyanosuccinimide

Abstract

Herein we disclose a three-component strategy to access quaternary centers bearing nitriles by cobalt-catalyzed CÀH bond activation and sequential addition to internally substituted 1,3-dienes and an electrophilic cyanating reagent with high regio and stereocontrol. 2-Aryl and alkyl monosubstituted dienes provide a-aryl and a-alkyl a-methyl-substituted nitriles, respectively. An even wider variety of functionality can be installed at the quaternary carbon by using 1,2-disubstituted dienes. The synthetic utility of the nitrile products was successfully demonstrated by various transformations, including conversions to g-lactones and tetrazoles. The observed connectivity in the products along with studies with deuterium labeled reactants provide insight into the mechanism. Formation of a 7-membered cobaltacycle by C À H activation and migratory insertion of the diene is followed by b-hydride elimination and hydride reinsertion to give a 6-membered cobaltacycle that then reacts with the cyanating agent.