Cobalt-mediated [2+2+2] cycloaddition versus C-H and N-H activation of pyridones and pyrazinones with alkynes: an experimental study.
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.
Aubert
Corinne
C
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.
Betschmann
Patrick
P
Eichberg
Michael J
MJ
Gandon
Vincent
V
Heckrodt
Thilo J
TJ
Lehmann
Jürg
J
Malacria
Max
M
Masjost
Birgit
B
Paredes
Elisa
E
Vollhardt
K Peter C
KP
Whitener
Glenn D
GD
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*
D000480:Alkynes; D007202:Indicators and Reagents; D017953:Isocyanates; D009570:Nitriles; D011719:Pyrazines; D011728:Pyridones; D003035:Cobalt