Nitrosylsulfuric acid was found to be an efficient oxidant for converting internal arylalkynes into their corresponding benzils. This 1,2-dicarbonylation proceeds under mild conditions at ambient temperature in nitromethane in the presence of catalytic amounts of iodine, affording benzils in 30-99% yields. Replacing nitromethane with acetonitrile crucially influences the composition of the products, with the main reaction products being substituted 1,3-oxazoles. The mechanism of the transformations was investigated by experiments with H218O.
Bondarenko et al. (Mon,) studied this question.
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