Synthesis and structure of 4-hydroxy-4-fluoroalkyl-1,4-dihydroimidazo[5,1-c][1,2,4]triazines

A Convenient Approach to 4,7‐Dihydrotetrazolo [5,1‐c][1,2,4]triazine Synthesis

“…The use of 19 F‐NMR spectroscopy data appears more convenient, since the neighboring carbon atoms make chemical shifts of fluorine atoms in α‐CF 3 or α‐CF 2 groups in the open‐chain 2‐(het)arylhydrazono‐1,3‐dicarbonyl compounds and cyclic dihydroazolotriazines different. In accordance with the literature data [23–25], the signals of fluorine atoms in α‐CF 3 or α‐CF 2 groups attached to sp 3 ‐hybridized carbon atom in azolotriazines A are observed in a stronger field {δ(α‐CF 3 ) 83–85, δ(α‐CF 2 ) 45 ppm} compared to those in (het)arylhydrazones B , where α‐CF 3 or α‐CF 2 groups are connected to sp 2 ‐hybridized carbon atom {δ(α‐CF 3 ) 90–93, δ(α‐CF 2 ) 49–52 ppm} [29].…”

“…The fluorinated heterocycles 3Ab , 3Ac , 3Ad , 3Ae , 3Af and 4Ab , 4Ac , 4Ad in the solid state are found to exist in the dihydrotetrazolotriazine form A , that capable to undergo ring‐chain isomerism as a result of C7―N7a bond cleavage in solution. This is typical for the previously obtained 4‐hydroxy‐4‐polyfluoroalkyl‐1,4‐dihydroazolo[5,1‐ c ][1,2,4]triazines [23–25]. These heterocycles have been found to exist mainly (>70%) as the cyclic isomer A in solution.…”

“…Our previous study showed the structure of hetaryl component to exert determinative influence on the result of azo coupling between fluoroalkyl‐containing 1,3‐dicarbonyl compounds and hetaryldiazonium salts. Thus, the reactions of polyfluoroalkyl‐containing 1,3‐diketones and 3‐oxo esters with hetaryldiazonium chlorides having the fragment NH in α‐position (1,2,4‐triazolyl‐3‐, 4‐ethoxycarbonylpyrazolyl‐3‐, and 4‐ethoxycarbonylimidazolyl‐5‐diazonium chlorides) [23–25] gave the stable 4‐hydroxy‐4‐polyfluoroalkyl‐1,4‐dihydroazolo[5,1‐ c ][1,2,4]triazines rather than expected open‐chain 2‐hetarylhydrazono‐1,3‐dicarbonyl compounds. At the same time, antipyrinyldiazonium salt in these reactions resulted in 2‐antipyrinylhydrazono‐1,3‐dicarbonyl compounds [26].…”

1,3-Diketones. Synthesis and properties

“…Polyfluoroalkyl-substituted dihydroimidazotriazines were synthesized by azo coupling of fluorinated 1,3-diketones with 4-ethoxycarbonyl-1H-imidazole-5diazonium chloride [132] (Scheme 117). The products in crystal were found to have structure B, while in solution ring-chain isomerism is possible via dissociation of the C 4 -N 5 bond, which is especially characteristic for compounds with the R F substituent longer than C 1 .…”

Non-aromatic azolo[5,1-c][1,2,4]triazines: a pot, atom and step economic (PASE) synthesis, mechanistic insight and fluorescence properties

“…5 However several examples of dihydroazolo [5,1-c] [1,2,4]triazines were obtained when trisubstituted enamines were used. 5,6,8 1,4-Dihydroazolo [5,1-c] [1,2,4]triazines previously described in the literature [11][12][13][14][15][16][17][18][19] were synthesized through the reaction of diazoazoles with CH-acids and subsequent intramolecular cyclization of hydrazone intermediates. [11][12][13][14][15] These compounds are attractive due to the wide spectrum of their biological activity.…”