The Dimroth rearrangement of 1-substituted 5-amino-l,2,3-triazoles into 5-anilinotriazoles can be carried out with several substituents at the 4-position (aryl, COOR, COOH, CONH2, H), but fails for a 4-cyano group. During our investigations on the thermal rearrangement of 5-azido-1 -phenyl-l.2,3-triazoles into tetrazole derivatives, we also noticed that the corresponding 4-cyano compound @, R=Ph) did not rearrange, but gave an untractable tar on thermolysis.2 In order to overcome this problem we have now activated the triazole for ring opening by introducing strong electron-withdrawing groups at the 1 -position and, indeed, observed a clean rearrangement.The 5-aminotriazoles u , b used in this work were prepared by condensation of malononitrile with 4-azidopyridine or p-nitrophenyl azide in alcohol and in the presence of a base (NaOEt for u and NEt3 for B, yields 80%).3 Since the amine function in 1 is not amenable to nitrosation either by the classical method (NaN02/HCI) or by its recent modification (NaNO /CF COOH),4 the diazo transfer reaction with tosyl aide5 was utilized to obtain a -h in 30-37% yield (after purification by column chromatography).
Recently, Kanakarajan et al.' claimed that nitrosation of aromatic amines with sodium nitrite in anhydrous trifluoroacetic acid followed by treatment with sodium azide is the method of choice for preparing azides from insoluble or deactivated amines. The method, however, was only exemplified with benzene derivatives and the question arises whether deactivated heterocyclic amines can likewise be converted into the corresponding azides.In our previous work we have reported that the 5-aminotriazoles Q,h, having strong electronwithdrawing groups at the 1-and 4-positions, cannot be converted into the azides &, ! 2 by the classical diazotization method in hydrochloric acid. We had solved this problem by utilizing the diazo transfer reaction with tosyl azide under basic conditions, yielding a a , h in 35 and 39% yield after purification by column chromatography.When the reaction of lawith NaN02/NaN3 was carried out in trifluoroacetic acid following the procedure of Kanakarajan' and the mixture then worked up by addition of aqueous NaHC03, the sodium salt of Q (mp 245"C, dec.) was isolated in 68% yield. Acidification of this salt yielded the open-chain diazoamidine a.Similarly, when (mp 175"C, dec.) was obtained directly in 32% yield (after crystallization from acetone).
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