title: Competitive intramolecular C-C vs. C-O bond coupling reactions toward C6 ring-fused 2-pyridone synthesis.
abstract: An interesting competitive C-C vs. C-O bond coupling reaction on N,3,5-trisubstituted pyridones is reported. These coupling reactions provided selective access to C- or O-ring-fused pyridones, both at the challenging C6-pyridone position. 1,6-C-Annulated pyridones were generally achieved in good yields with excellent chemoselectivity under Pd(0) conditions. On the other hand, full C6-regioselective Csp(2) aryloxylation was achieved under oxidative coupling promoted by silver salts to access 5,6-O-annulated pyridones. Based on various experiments and observations, mechanistic evidence of these competitive reactions was provided and it was proposed that C-O bond formation proceeded through radical cyclization. These processes were performed under mild reaction conditions and offer an efficient and attractive methodology to selectively access a large scope of C-arylated and O-arylated pyridones of biological interest.
authors.affiliation: Laboratoire de Chimie, URCOM, EA 3221, INC3M CNRS FR-3038, Normandie Université (Université du Havre), UFR des Sciences et Techniques de l'Université du Havre, 25 Rue Philippe Lebon, B.P. 1123, F-76063 Le Havre Cedex, France. lawsona@univ-lehavre.fr.
authors.forename: T
authors.initials: T
authors.lastname: Lepitre
authors.forename: C
authors.initials: C
authors.lastname: Pintiala
authors.forename: K
authors.initials: K
authors.lastname: Muru
authors.forename: S
authors.initials: S
authors.lastname: Comesse
authors.forename: A
authors.initials: A
authors.lastname: Rebbaa
authors.forename: A M
authors.initials: AM
authors.lastname: Lawson
authors.forename: A
authors.initials: A
authors.lastname: Daïch
mesh_terms: D002244:Carbon / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010100:Oxygen / Q000737:chemistry*; D011728:Pyridones / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
chemical_list: D011728:Pyridones; C017679:2-hydroxypyridine; D002244:Carbon; D010100:Oxygen