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 ‐Csp 2 ‐H acylmethylation of 2‐aryl‐2,3‐dihydrophthalazine‐1,4‐diones with α‐carbonyl sulfoxonium ylides is achieved through a Ru II ‐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 BF 3 ⋅OEt 2 mediated conditions, respectively. Of these, the BF 3 ⋅OEt 2 ‐mediated cyclization proceeded in DMSO as a solvent and a methylene source via dual C−C and C−N bond formations.