Nickel Peroxide Dehydrogenation of Oxygen-, Sulfur-, and Nitrogen-Containing Heterocycles

Twenty-seven partially reduced O-, S-, and N-containing heterocvcles have been oxidized by the use of nickel peroxide. Of particular interest were the conversions of several oxazolines to the corresponding oxazoles, a conversion apparently without precedent in the chemical literature, and the efficient oxidation of thiazolines to thiazoles. Since Ni0₂ can effect thiazoline dehydrogenations in the presence of other functionalities, as may be judged by the successful oxidation of phleomycin A₂ to bleomycin A₂, the oxidant should be of utility for the preparation of natural products containing thiazoles.