title: Cobalt-mediated [2+2+2] cycloaddition versus C-H and N-H activation of pyridones and pyrazinones with alkynes: an experimental study.
abstract: The reactivity of a range of pyridone and pyrazinone derivatives towards alkynes in the presence of cyclopentadienylcobaltbis(ethene) has been investigated. Depending on the nature of the substrates, [2+2+2]- or [2+2] cycloaddition, C-H, or N-H activation may occur. In the case of pyridones, the first three predominated with N-protected derivatives, whereas substrates containing N-H bonds followed an N-H activation pathway. The [2+2+2] cycloaddition of an N-butynylisoquinolone was applied successfully to the total synthesis of anhydrolycorinone. Pyrazinone substrates showed similar patterns of reactivity.
authors.affiliation: Université Pierre et Marie Curie-Paris 6, Laboratoire de Chimie Organique (UMR CNRS 7611), Institut de Chimie Moléculaire (FR 2769), case. 229, 4 place Jussieu, 75252 Paris cedex 05, France.
authors.forename: Corinne
authors.initials: C
authors.lastname: Aubert
authors.forename: Patrick
authors.initials: P
authors.lastname: Betschmann
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Eichberg
authors.forename: Vincent
authors.initials: V
authors.lastname: Gandon
authors.forename: Thilo J
authors.initials: TJ
authors.lastname: Heckrodt
authors.forename: Jürg
authors.initials: J
authors.lastname: Lehmann
authors.forename: Max
authors.initials: M
authors.lastname: Malacria
authors.forename: Birgit
authors.initials: B
authors.lastname: Masjost
authors.forename: Elisa
authors.initials: E
authors.lastname: Paredes
authors.forename: K Peter C
authors.initials: KP
authors.lastname: Vollhardt
authors.forename: Glenn D
authors.initials: GD
authors.lastname: Whitener
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D003035:Cobalt / Q000737:chemistry*; D018360:Crystallography, X-Ray; D003500:Cyclization; D007202:Indicators and Reagents; D017953:Isocyanates / Q000737:chemistry; D008958:Models, Molecular; D009570:Nitriles / Q000737:chemistry; D010084:Oxidation-Reduction; D011719:Pyrazines / Q000737:chemistry*; D011728:Pyridones / Q000737:chemistry*
chemical_list: D000480:Alkynes; D007202:Indicators and Reagents; D017953:Isocyanates; D009570:Nitriles; D011719:Pyrazines; D011728:Pyridones; D003035:Cobalt