BiVO₄ Facilitated Aerobic Oxidation Of Alkynes Under Visible-light Irritation

1,2-Diketones are very useful synthetic intermediates that are widely used in the construction of functional materials,biologically active compounds and many other heterocyclic products.Besides,1,2-diketone fragment itself is found in a variety of bioactive moleculars and natural products.Therefore,the development of a highly effective protocol for the synthesis of 1,2-diketones is pretty desirable.For the first time,we developed a facile and green protocol for the synthesis of 1,2-diketones catalyzed by a recyclable photocatalyst BiVO₄ under visible light irradiation at room temperature.The main contents are shown as follows:1.The reaction conditions,such as light sources,semiconductors,thiols and solvents were systematically screened using diphenylethyne as a model substrate.We found that the best result was obtained when using 12 W blue LED as light source,50 mol% of BiVO₄@3 as promoter,100 mol% 4-chlorothiophenol as catalyst,acetonitrile?MeCN?as solvent at room temperature under air for 16 h.Under the optimized conditions,the aerobic oxidation of diphenylethyne proceeded smoothly and lead to 83% yield of 1,2-diphenylethane-1,2-dione.Vairous functional group-substituted diarylethynes were well tolerated and a series of 1,2-diaryl ethadiones were successfully syhthesized.We did not observe significant deterioration of activity in the recovered catalyst even after using it three times.2.The study on BiVO₄ samples showed that pH values of hydrothermal precursor solutions would affect crystal components,morphologies,visible-light response as well as the catalytic performance.The sample BiVO₄@3 which was synthesized under pH value of 3 existed the highest catalytic activity.