Unexpected Imidazoquinoxalinone Annulation Products in the Photoinitiated Reaction of Substituted-3-Methyl-Quinoxalin-2-Ones with N-Phenylglycine
Author
dc.contributor.author
Fuente, Julio R. De la
Author
dc.contributor.author
Cañete, Álvaro
es_CL
Author
dc.contributor.author
Jullian Matthaei, Carolina
es_CL
Author
dc.contributor.author
Saitz Barría, Claudio
es_CL
Author
dc.contributor.author
Aliaga, Christian
es_CL
Admission date
dc.date.accessioned
2014-01-13T18:36:04Z
Available date
dc.date.available
2014-01-13T18:36:04Z
Publication date
dc.date.issued
2013
Cita de ítem
dc.identifier.citation
Photochemistry and Photobiology, 2013, 89: 1335–1345
en_US
Identifier
dc.identifier.other
DOI: 10.1111/php.12162
Identifier
dc.identifier.uri
https://repositorio.uchile.cl/handle/2250/121752
General note
dc.description
Artículo de publicación ISI
en_US
Abstract
dc.description.abstract
Photoinduced electron transfer between N-phenylglycine
(NPG) and electronically excited triplets of 7-substituted-3-
methyl-quinoxalin-2-ones in acetonitrile generate the respective
ion radical pair, where by decarboxylation the phenyl-aminoalkyl
radical, PhNHCH2•, is generated. This radical reacts
with the 3-methyl-quinoxalin-2-ones ground states, leading
to the product 2. Other, unexpected, 7-substituted-1,2,3,3atetrahydro-
3a-methyl-2-phenylimidazo[1,5-a]quinoxalin-4(5H)-
ones, annulation products, 3a–f, were generated; likely by the
addition of two PhNHCH2• radicals, to positions 3 and 4 of
the quinoxalin-2-ones. The reaction mechanism includes a
photoinduced one electron transfer initiation step, propagation
steps involving radical intermediates and NPG with radical
chain termination steps that lead to the respective
products 2a–f and 3a–f and NPG by-products. The proposed
mechanism accounts for the strong dependency found for the
initial photoconsumption quantum yields on the electronwithdrawing
power of the substituent. Therefore, photolysis
of common reactants widely used such as NPG and substituted
quinoxalin-2-ones may provide a simple synthetic way
to the unusual, unreported tetrahydro-imidazoquinoxalinones
3a–f.