Abstract Dichloro-and dibromoformaldoximes are useful 1, 3-dipolar cycloaddition reagents. They are conveniently preparated in situ, in high yields by dihalogenation of glyoxalic acid aldoxime with N-bromo-and N-chlorosuccinimide or tert-butyl hypochlorite. Dehydrohalogenation with potassium hydrogen carbonate in the presence of alkenes gives 3-halo-isoxazolines in a one-pot reaction. Reduction with iron pentacarbonyl gives β- ...
