title: Metal-Free, Visible Light-Photocatalyzed Synthesis of Benzo[b]phosphole Oxides: Synthetic and Mechanistic Investigations.
abstract: Highly functionalized benzo[b]phosphole oxides were synthesized from reactions of arylphosphine oxides with alkynes under photocatalytic conditions by using eosin Y as the catalyst and N-ethoxy-2-methylpyridinium tetrafluoroborate as the oxidant. The reaction works under mild conditions and has a broad substrate scope. Mechanistic investigations have been undertaken and revealed the formation of a ground state electron donor-acceptor complex (EDA) between eosin (the photocatalyst) and the pyridinium salt (the oxidation agent). This complex, which has been fully characterized both in the solid state and in solution, turned out to exhibit a dual role, i.e., the oxidation of the photocatalyst and the formation of the initiating radicals, which undergoes an intramolecular reaction avoiding the classical diffusion between the two reactants. The involvement of ethoxy and phosphinoyl radicals in the photoreaction has unequivocally been evidenced by EPR spectroscopy.
authors.affiliation: Normandie University , LCMT, ENSICAEN, UNICAEN, CNRS, 14000 Caen, France.
authors.forename: Valentin
authors.initials: V
authors.lastname: Quint
authors.affiliation: Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, rue Jean Starcky, 68057 Cedex, Mulhouse, France.
authors.forename: Fabrice
authors.initials: F
authors.lastname: Morlet-Savary
authors.affiliation: Normandie University , LCMT, ENSICAEN, UNICAEN, CNRS, 14000 Caen, France.
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Lohier
authors.affiliation: Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, rue Jean Starcky, 68057 Cedex, Mulhouse, France.
authors.forename: Jacques
authors.initials: J
authors.lastname: Lalevée
authors.affiliation: Normandie University , LCMT, ENSICAEN, UNICAEN, CNRS, 14000 Caen, France.
authors.forename: Annie-Claude
authors.initials: AC
authors.lastname: Gaumont
authors.affiliation: Normandie University , LCMT, ENSICAEN, UNICAEN, CNRS, 14000 Caen, France.
authors.forename: Sami
authors.initials: S
authors.lastname: Lakhdar