The reaction of hydroxylaminehydrochloride with differently substituted phenyldibenzoylethylene has been investigated. Both cyclicnitrone and 1,2-oxazine have been isolated and characterized by one- and two-dimensional NMR data and also by single crystal X-ray analysis. The reaction of hydroxylaminehydrochloride with differently subtituted phenyldibenzoylethylene has been investigated. Both cyclic