Selective oxygenation of alkynes: a direct approach to diketones and vinyl acetate

Arylalkynes can be converted into alpha-diketones with the use of a copper catalyst, and also be transformed into vinyl acetates under metal-free conditions, both in the presence of PhI(OAc)(2) as an oxidant at room temperature. A series of substituted alpha-diketones were prepared in moderate to good yields. A variety of vinyl halides could be regio- and stereo-selectively synthesized under mild conditions, and I, Br and Cl could be all easily embedded into the alkynes.