Alcohol-Incorporating Diels-Alder Dimerization of In Situ Formed ortho-Quinamine via Co-Nitrenoid Insertion

Abstract

We disclose herein a Cp*Co(III)(LX)-catalyzed dearomative Diels-Alder dimerization of 2,6-disubstituted phenyl azidoformates. Upon the postulated cobalt-nitrenoid insertion into the neighboring ortho-carbon, the key intermediate of ortho-quinamine was generated for the subsequent dimeric cycloaddition process. A series of experimental and computational studies suggested that the quinolinol ligand of the cobalt catalyst plays a crucial role in the alcoholic solvent incorporation into the o-quinamine moiety, thereby enabling the Diels- Alder dimerization to furnish the bridged tricyclic bisamidation products.