An original, facile and highly efficient method for the in situ generation of cyclic enolate-iminium 1,4-dipoles via unique thermal decomposition of easily available dipyrazolodioxadiazocines has been developed. Various substituted pyrazolo[5,1-d][1,3,5]dioxazines have been prepared in high yields via unusual cycloconversion of dipyrazolodioxadiazocines in the presence of ketones. Furthermore, the developed method is 100% atom economical and proceeds under metal-, catalyst- and solvent-free conditions.