Synthesis of Homoallylic Alcohols with Acyclic Quaternary Centers through CoIII-Catalyzed Three-Component C-H Bond Addition to Internally Substituted Dienes and Carbonyls

An efficient Co-III-catalyzed three-component strategy to prepare homoallylic alcohols containing acyclic quaternary centers is disclosed. This transformation enables the introduction of two C-C sigma bonds through C-H bond activation and sequential addition to internally substituted dienes and a wide range of aldehydes and activated ketones. Isoprene and other internally monosubstituted dienes are effective inputs, with the reaction proceeding with high diastereoselectivity for those substrate combinations that result in more than one stereogenic center. Moreover, the opposite relative stereochemistry can be achieved by employing 1,2-disubstituted dienes. A mechanism for the transformation is proposed based upon the relative stereochemistry of the products and studies with isotopically labeled starting materials.