Ruthenium Catalyzed C−H Acylmethylation of N-Arylphthalazine-1,4-diones with α-Carbonyl Sulfoxonium Ylides: Highway to Diversely Functionalized Phthalazino-fused Cinnolines

Abstract

A direct ortho-Csp2-H acylmethylation of 2-aryl-2,3-dihydrophthalazine-1,4-diones with α-carbonyl sulfoxonium ylides is achieved through a RuII-catalyzed C−H bond activation process. The protocol featured high functional group tolerance on the two substrates, including aryl-, heteroaryl-, and alkyl-substituted α-carbonyl sulfoxonium ylides. Thereafter, 2-(ortho-acylmethylaryl)-2,3-dihydrophthalazine-1,4-diones were used as potential starting materials for the expeditious synthesis of 6-arylphthalazino[2,3-a]cinnoline-8,13-diones and 5-acyl-5,6-dihydrophthalazino[2,3-a]cinnoline-8,13-diones under Lawesson's reagent and BF3⋅OEt2 mediated conditions, respectively. Of these, the BF3⋅OEt2-mediated cyclization proceeded in DMSO as a solvent and a methylene source via dual C−C and C−N bond formations.