Triazole rings, condensation

A series of stilbenyl derivatives with two condensed triazole rings is shown in Table XIII. 

Closure of the triazole ring can be achieved either by oxidative formation of the N-N bond, or condensation of an fV-aminopyridone. The latter was formed by iV-amination of pyridines with mesitylhydroxylamine (MSH), or by forming the pyridine ring, starting from cyanoacetic hydrazide with malononitrile or 2-cyanoacrylates. 

Condensation of active methylene compounds with cyanoacetic hydrazide-derived hydrazones led to a one-pot formation of pyridine and triazole rings. 

Condensation with Triazole Ring/s Coburn and Jackson studied in detail the synthesis of various picryl and picrylamino-substituted 1,2,4-triazoles and 3,3 -bi-... 

A number of compounds in which two triazole rings are condensed on a single benzene nucleus have also been found to undergo the Anil Synthesis.73-75 For example, 2-(/>-tolyl)-7-phenylbenzo[l,2-t/ 3,4-[Pg.228]

The [l,2,4]triazolo[l,5- ]pyridine system is usually constructed by the closure of the triazole ring either by oxidative formation of the NN bond or by condensation of the N-aminopyridine derivatives . Various compounds 78 were obtained by the oxidation of the amidine 77 with Mn02 (Scheme 47) <2003IJB2901, 2005ARK(xiii)21>. A dehydrative cyclization by treatment of formamidoximes 79 with trifluoroacetic anhydride (TFAA) has been used in the synthesis of 80 (Scheme 48), which are key building blocks in the preparation of DPP (IV) inhibitors <2005EJ03761, 2006JME3614>. 

Introduction of amino groups Introduction of conjugation Condensation with a triazole ring. 

Resistance of the triazole ring to reduction permits reductive condensations as in Scheme 50 (72JMC694). 

Triazole rings may form condensed ring systems with 1,2,3,4-, 1,2,3,5-, or 1,2,4,5-tetrazines, but only l,2,4-triazolo-l,2,4,5-tetrazines have been synthesized. 

The condensed 1,2,4-triazole ring of 577 was formed as a result of condensing the jS-D-ribofuranosylcarbodithioate 512 with 2-hydrazino-4-hydroxy-6-methylpyrimidine. Unlike the l,2,4-triazolo[l,5-c]pyrimidine analog 568, the l,2,4-triazolo[4,3-fl]pyrimidin-3-yl C-nucleoside 577 did not undergo Dimroth rearrangement (89MI5) (Scheme 154). 

Reviews of the coordination chemistry of this type of ligand have been published for pyrazoles and imidazoles, and to a lesser extent for the triazoles and tetrazoles. Many azole ligands are commercially available or are easily synthesized by a variety of condensation and ring-closure reactions. ... 

Although numerous dihydro-1,2,5-benzotriazepin-4-ones and fused 1,2,5-benzotriazepines condensed with one more heterocyclic ring, such as pyrrole and triazole rings, have been reported <84CHE719>, to date fully unsaturated simple 1,2,5-benzotriazepines are still unknown. 

N-Condensed 1,2,4-triazole ring and o-cyanamino-N-heterocyclics from 1,1-dilorohydrazones... 

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