1.2.3- Triazole-4-carboxylates

Triazole-4-carboxylic acid, 5-chloro-1-phenyl-UV, 5, 685 (55JA6532)... 

Triazole-4-carboxylic acid, 2-phenyl-cleavage reactions, 5, 697... 

Heating 4-oxo-4//-pyrido[l, 2-n]pyrimidine-3-diazonium tetrafluorobo-rate and its 8-methyl derivative in alcohol at 60-90 °C for 15 min to 5h gave alkyl 1-(2-pyridyl)- and 1-(4-methyl-2-pyridyl)-l//-1,2,3-triazole-4-carboxylates (00H(53)1793). 

Amino-S-hy droxy-1,2,3-triazole-4-carboxylic acid hydrazide 1 A218... 

Ami no-5-hydroxy-1,2,3-triazole- 4 carboxylic acid hydrazide or 1-Amino-4-hydrazido-carbon-5-hydroxytri azole,(Called 1-Amino-4-hydrazidocarbon-5 oxytriazoI in Ref 2), HO-C-N(NH ) N, mw 158.13, N... 

Ethyl l-hydroxy-l//-l,2,3-triazole-4-carboxylate (20) has been investigated as an additive to carbodiinoides particularly for solid-phase peptide synthesis. No racemization was observed when Fmoc-protected anoino acids were coupled to the resin-bound peptides, except for histidine residues which under these reaction conditions racenoized extensively unless the activation time was kept to one minute and three equivalents of ethyl 1-hydroxy-1//-1,2,3-triazole-4-carboxylate (20) were added. Under the latter conditions no racemization was detected.The efficiency of this newly developed method has been well documented by the successful synthesis of deglycosylated human erythropoietin.t ... 

Upon UV irradiation, ethyl 5-amino-l-phenyl-l,2,3-triazole-4-carboxylate (40) does not expel N2 to give ketenimines or aziridines. Instead, in the presence of triphenylene as photosensitizer, 40 is smoothly isomerized, as a first example of a photo-Dimroth rearrangement,163 to ethyl 5-anilino-1,2,3-triazole-4-carboxylate (298).164 The mechanism is explained by a radical rearrangement, e.g., 2971-297III (cf. Scheme 81). This isomerization type was observed also with 5-amino-1,4-diphenyl-1,2,3-triazoles.165... 

Triazole-4-Carboxylic Acids and Their Functional Derivatives 95... 

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