Normandie University , LCMT, ENSICAEN, UNICAEN, CNRS, 14000 Caen, France.
Institut de Science des Matériaux de Mulhouse IS2M, UMR CNRS 7361, UHA, 15, rue Jean Starcky, 68057 Cedex, Mulhouse, France.
J Am Chem Soc. 2016 Jun 15;138(23):7436-41. doi: 10.1021/jacs.6b04069. Epub 2016 Jun 1.
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.
高功能化苯并[b]膦氧化物可由芳基氧化膦与炔烃在光催化条件下反应得到，所用的催化剂为曙红 Y，氧化剂为 N-乙氧基-2-甲基吡啶四氟硼酸盐。该反应在温和条件下进行，底物适用范围广泛。我们进行了机理研究，结果表明曙红（光催化剂）和吡啶盐（氧化剂）之间形成了基态电子给体-受体复合物（EDA）。该配合物在固态和溶液中均得到了充分的表征，结果表明其具有双重作用，即光催化剂的氧化作用和引发自由基的形成作用，该自由基通过分子内反应避免了两个反应物之间的经典扩散。电子顺磁共振（EPR）光谱明确证明了乙氧基和膦酰基自由基在光反应中的参与。
