Copper-catalyzed domino sequences: a new route to pyrido-fused quinazolinones from 2′-haloacetophenones and 2-aminopyridines

Abstract

A new pathway to access pyrido-fused quinazolinones via a Cu(OAc)2-catalyzed domino sequential transformation between 2′-haloacetophenones and 2-aminopyridines was demonstrated.

Serendipitous Synthesis of Pyridoquinazolinones via an Oxidative C–C Bond Cleavage

“…Furthermore, the condensation reaction with 2-aminopyridine (PyNH 2 ) generates the reversible enamine B , which upon SET transformation with Cu­(I)/Py under an oxygen atmosphere, leads to the reactive peroxy radical intermediate C . The subsequent reaction of enamine with peroxy radical yields dioxetane derivative D . ,, Tautomeric ring opening of dioxetane and imine hydrolysis to form α-keto copper-peroxy intermediate E followed by base-mediated oxidation deliver F . , Furthermore, copper-induced oxidation of F is anticipated to give G , which upon concomitant tautomerization and intramolecular cyclization, leads to H . , The following decarboxylation and oxidation of the resulting aminol afford required product 5a …”

Copper‐mediated annulation of 2‐aminoacetophenones and 2‐bromopyridines

“…[10] Our group later presented a method for oxidative coupling of 2bromoacetophenones and 2-aminopyridines. [11] The reactions performed well under the assistance of Cu(OAc)2 catalyst. Recently, Kaliappan and coworkers developed a two-step coupling of 2'haloacetophenones and 2-aminopyridine, in the presence of CuI catalyst.…”

Copper-Catalyzed Domino-Double Annulation of o-Aminobenzamides with 2-Iodoisothiocyanates for the Synthesis of 12H-Benzo[4,5]thiazolo[2,3-b]quinazolin-12-ones

“…8 Phan and co-workers demonstrated that 12H-benzo [4,5]thiazolo[2, 3b]quinazolin-12-ones could be prepared by a copper-catalyzed oxidative C−C bond cleavage pathway (Scheme 1b). 9 Subsequently, Kaliappan and co-workers developed a similar one-pot two-step synthesis of 12H-benzo [4,5]thiazolo[2, 3b]quinazolin-12-one. 10 Molina and co-workers reported the synthesis of 12H-benzo [4,5]thiazolo[2, 3-b]quinazolin-12-ones by a combination of aza-Wittig methodology and copper-catalyzed heteroarylation (Scheme 1c).…”

“…For example, Huang and co-workers developed a simple and efficient synthesis of 12 H -benzo­[4,5]­thiazolo­[2,3- b ]­quinazolin-12-ones by copper-catalyzed domino reaction of isatins and 2-bromobenzo­[ d ]­thiazoles (Scheme a) . Phan and co-workers demonstrated that 12 H -benzo­[4,5]­thiazolo­[2,3- b ]­quinazolin-12-ones could be prepared by a copper-catalyzed oxidative C–C bond cleavage pathway (Scheme b) . Subsequently, Kaliappan and co-workers developed a similar one-pot two-step synthesis of 12 H -benzo­[4,5]­thiazolo­[2,3- b ]­quinazolin-12-one .…”