1.2.4- Triazole-3-carboxylic acid, 5-diazo

The cycloaddition of DMAD and EP to 7-acylamino-3-azidomethyl-3-cephem-4-carboxylic acid derivatives (88) gave the expected 1,2,3-triazole derivatives 89 and 90.813 A similar addition of MP to the diazo compound 91 gave 92,814 and the nitrone 93 gave 94 with DMAD, a rearrangement having taken place.815... 

Nitrosomino-a-sym-triazole- 3- carboxylic Acid or S-Nitrosanino-lH-l, 4-triazole-3-carboxylic Acid [Called in Beil, 5-Nitros-imino-1.2.4-triazol-carbonsaure-(3) or 5-Diazo-1.2.4-triazo 1-carbons aure-(3)]> ON-HN-C-NH-N, 0N-N C-NH-N... 

The transformation of an active CH compound into the corresponding diazo derivative with -toluenesulfonyl azide has been designated a diazo transfer reaction and possesses a variety of preparative uses. The method has been useful for the syntheses of diazo derivatives of cyclopentadiene, 1,3-dicar-bonyl compounds, 1,3-disulfonyl compounds,1,3-keto-sulfonyl compounds, ketones, " carboxylic acid esters, and /3-keto imines. Further reaction of these diazo intermediates can lead to azo compounds,"- " 1,2,3-triazoles, and pyrazolinones. ... 

Reaction of ethyl 5-amino-3-methylthio-l//-pyrazol-4-carboxylate 267 with sodium nitrite in the presence of hydrochloric acid gives the diazo intermediate 268, which on treatment with active methylenic compounds such as ethyl a-chloroacetate or a-chloroacetylacetone affords the hydrazonyl chlorides 269 and 270, respectively, whose reaction with triethylamine in refluxing ethanol convert them into ethyl 4-hydro-2-methylthiopyrazolo[5,l-c]-[l,2,4]triazole-3,6-dicarboxylate 271 and ethyl 6-acetyl-4-hydro-2-methylthiopyrazolo[5,l-c][l,2,4]triazole-3-carboxy-late 272 (Scheme 23) <2001MI1>. 

The 1,3-dipolar addition of secondary diazo-compounds to 1,3,3-trimethylcyclo-propene affords 2,3-diazabicyclo[3,l,0]hex-3-enes [cf. (130)], but with diazoacetic ester this product, with an acidic proton at C-4, undergoes rearrangement to ethyl 3,4,4-trimethyl-l,4-dihydropyridazine-6-carboxylate. Further additions of phenyl azide to methylenecyclopropanes have shown that the presence of a carboxylate group in the three-membered ring causes the initially formed spirodihydrotriazole to undergo rearrangement to a 4-substituted 1,2,3-triazole. ... 

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