Regiospecificity of the nitrosation of di(gem-dichlorocyclopropanes) obtained from butadiene and isoprene

Nitrosation of di(gem-dichlorocyclopropane) with NOCl·2SO3 proceeds regiospecifically and in two stages to afford di(5-chloroisoxazol-3-yl). The introduction of a methyl group on one of the cyclopropane rings crucially influences the reactivity and mode of transformation of the substrate, leading to 3-chloro-5-methyl-5-(1,3,3-trichloroprop-2-en-1-yl)isoxazoline, the structure of which was established by X-ray single crystal diffractometry.