Methods for the synthesis of [1,2,5]oxadiazolo[3,4 c]cinnoline 5 oxides, which include the reaction of 3 nitramino 4 (R phenyl)furazans or their O methyl derivatives with electrophilic agents, have been developed. Unsubstituted [1,2,5]oxadiazolo[3,4 c]cinnoline 5 oxide was synthesized from 3 nitramino 4 phenylfurazan upon the action of phosphorus anhydride or oleum, as well as from O methyl derivative of 3 nitramino 4 phenylfurazan upon the action of H 2 SO 4 , MeSO 3 H, CF 3 CO 2 H and BF 3 •Et 2 O, while 6 , 7 , 8 , and 9 nitro substituted [1,2,5]oxadiazolo[3,4 c]cinnoline 5 oxides -from the corresponding 3 nitramino 4 (nitro phenyl)furazans upon the action of the H 2 SO 4 HNO 3 nitrating mixture. A suggestion has been made that an oxodiazonium ion is formed in these reactions from nitramines or their O methyl derivatives upon the action of electrophilic agents, which is further involved into the intra molecular reaction of electrophilic aromatic substitution (S E Ar) with the aryl group. The struc ture of [1,2,5]oxadiazolo[3,4 c]cinnoline 5 N oxides was confirmed by 1 H, 13 C, and 14 N NMR spectra. Theoretical studies by the B3LYP/6 311G(d,p) method of combined molecular system (O methylated 3 nitramino 4 phenylfurazan + [H 3 SO 4 ] + ) resulted in calculation of thermo dynamic parameters of the sequence of cascade elementary reactions leading to the formation of [1,2,5]oxadiazolo[3,4 c]cinnoline 5 oxide.
