Nitro derivatives of 2,1-benzisothiazoline 2,2-dioxide (benzosultams) undergo thermal elimination of sulfur dioxide yielding very reactive, non-isolable aza-ortho-xylylenes. It was found that this reaction can be performed in the injector of the gas chromatograph at 300 - 350°C and the formed aza-ortho-xylylenes can be trapped by appropriate reagents added to the injected solution. In the preliminary experiments aza-ortho-xylylenes were reacted with dienophiles (methyl acrylate, dimethyl maleate, vinyl acetate, N-phenylmaleimide etc.) resulting in the formation of the [4+2] cycloaddition reaction products, and also with nucleophilic reagents (alcohols, amines) to give appropriate adducts. In the absence of the trapping reagent dimers of aza-ortho-xylylenes were formed.