Functionalization of C_(sp~3)—H and C_(sp~2)-H Bonds: Synthesis of Spiroindenes by Enolate-Directed Ruthenium-Catalyzed Oxidative Annulation of Alkynes with 2-Aryl-l,3-dicarbonyl Compounds

摘要

The metal-catalyzed oxidative annulation of alkynes with aryl or alkenyl substrates bearing various heteroatom-containing functional groups has proven to be a versatile, efficient, and atom-economic strategy to access a range of valuable heterocyclic products. These processes generally rely upon coordination of the metal center to the heteroatom-containing functional group, which directs site selective C_(sp~2)— H bond cleavage to form the metallacycle A (Scheme 1 a). Coordination and migratory insertion of the alkyne and subsequent C—X (X = heteroatom) reductive elimination then forms the heterocyclic product.