Intramolecular 1,3‐Dipolar Cycloadditions of Aryl Azides with Alkynyl SubstituentsReaction of substituted 4‐chlorobut‐2‐ynes1with 2‐acetaminophenol and 2‐aminothiophenol, respectively, leads to the corresponding ethers and thioethers3that can be converted into the alkynyl substituted aryl azides4by diazotation and reaction with sodium azide. Intramolecular 1,3‐dipolar cycloaddition yields 4H‐[1,2,3]triazolo [5,1‐c][1,4] benzoxazines and benzothiazines5. In the same way 1,4‐bis(2‐acetaminophenoxy)but‐2‐yne6reacts to a 3‐(2‐azidophenoxy‐methyl)‐triazolobenzoxazine9. Its thermal dec