Cycloaddition-hydrosilylation of 1,6-Eneynes Using a Cobalt/iminopyridine Complex

Lu et al. have reported the cobalt complex-catalyzed intramolecular cycloaddition-hydrosilylation of 1,6-eneynes. In this reaction, previously prepared and isolated cobalt-iminopyridine complex (Co-IP complex), from cobalt chloride and a ligand of trans-2,6-diisopropyl-N-(2-pyridylmethylene)aniline, is used as a pre-catalyst for this transformation. In the presence of hydrosilanes, the Co-IP complex is reduced by sodium borohydride to generate a cobalt-hydride species which catalyzes the subsequent intramolecular cycloaddition-hydrosilylation of 1,6-eneynes to afford the desired silyl group-substituted 5-membered rings. This reaction can be effectively used for synthesis of functionalized 5-membered cyclic compounds due to having a wide reaction scope.