The reaction between an unfunctionalized conjugated diene and a nitroarene under CO pressure and at 100 degreesC, catalyzed by [Pd(Phen)(2)] [BF4](2) (Phen = 1, 10-phenanthroline), affords the corresponding hetero-Diels-Alder adduct (oxazine) in up to 91% yields in one pot. If the reaction mixture is then heated to 200 degreesC, the oxazines are converted into the corresponding N-arylpyrroles in good yields. Pressures as low as 5 bar can be employed, and 0.08% catalyst is sufficient to effect the transformation. The reaction can be equally run by employing the nitroarene or the diene as limiting agent and works well for nitroarenes bearing either electron-withdrawing or mildly electron-donating substituents. A moderate steric hindrance on the nitroarene (o-methyl) is well tolerated, but 1,4-disubstituted-1,3-dienes are not suitable substrates.
Synthesis of oxazines and N-arylpyrroles by reaction of unfunctionalized dienes with nitroarenes and carbon monoxide, catalyzed by palladium-phenanthroline complexes / F. Ragaini, S. Cenini, D. Brignoli, M. Gasperini, E. Gallo. - In: JOURNAL OF ORGANIC CHEMISTRY. - ISSN 0022-3263. - 68:2(2003), pp. 460-466.
|Titolo:||Synthesis of oxazines and N-arylpyrroles by reaction of unfunctionalized dienes with nitroarenes and carbon monoxide, catalyzed by palladium-phenanthroline complexes|
RAGAINI, FABIO ATTILIO CIRILLO (Primo)
CENINI, SERGIO (Secondo)
GASPERINI, MICHELA BARBARA (Penultimo)
GALLO, EMMA (Ultimo)
|Parole Chiave:||Aromatic carboxylic-acid; C-H functionalization; diels-alder adducts; reductive carbonylation; ruthenium complexes; 1,3-diene synthesis; enyne metathesis; cross-metathesis; bond formation; ethylene|
|Settore Scientifico Disciplinare:||Settore CHIM/03 - Chimica Generale e Inorganica|
|Data di pubblicazione:||2003|
|Digital Object Identifier (DOI):||http://dx.doi.org/10.1021/jo0260589|
|Appare nelle tipologie:||01 - Articolo su periodico|