Alkyl 3-fluoroalkyl-3-oxopropionates in reactions with azolyldiazonium salts

Abstract

Alkyl 3 fluoroalkyl 3 oxopropionates react with antipyrinyldiazonium chloride to form 2 antipyrinylhydrazono 3 fluoroalkyl 3 oxopropionates. The use in these reactions of hetaryldiaz onium salts, containing NH group in the α position, leads to alkyl 7 fluoroalkyl 7 hydroxy 4,7 dihydroazolo[5,1 c]triazine 6 carboxylates. 3 Amino 1H 1,2,4 triazole, 3 amino 4 ethoxycar bonyl 1H pyrazole, and 5 amino 4 ethoxycarbonyl 1H imidazole were used as the heterocyclic component.

Reactivity of 3-substituted pyrazole-5-diazonium salts towards 3-azolyl enamines. Synthesis of novel 3-azolylpyrazolo[5,1-c][1,2,4]triazines

“…In the case of 3-methyl-1H-pyrazole-5-amine 5e we did not manage to isolate hydrosulfate salt 6e as a solid. Therefore, it was alternatively generated from aminopyrazole 5e by reaction with sodium nitrite in an aqueous solution of HBF 4 at low temperature (Scheme 2) and tetrafluoroborate salt 6e was used in situ in further studies. Enamines 8a-f were prepared by treatment of the corresponding 5-methylthiadiazole-4-carboxylate 7a,b or alkyl 5-methyl-3-arylisoxazole-4-carboxylates esters 7c-f with DMF-DMA in the presence of N-methylimidazole under reflux for six hours as has been reported earlier 33,34 (Scheme 3).…”

“…Similar to aromatic diazonium salts, they can couple with a very broad range of aromatic and heteroaromatic compounds 1,2 as well as with active methylene reagents [3][4][5][6] to form azo compounds and hydrazones, respectively. On the other hand, similarly to diazoalkanes, they react with alkenes, [7][8][9][10][11][12][13][14] alkynes, [8][9][10] enamines, 10,12,13,15 ynamines, 7,12,13,16 isocyanates [17][18][19][20][21][22][23] and isothiocyanates 24,25 to furnish a huge variety of heterocyclic compounds.…”

“…We turned our attention to reactions of diazopyrazoles 1 with enamines because they take place in a regioselective manner to form pyrazolo [5,1-c] [1,2,4]triazines as exclusive products in good yields. Scheme 1 shows a few known examples for formation of pyrazolotriazines 2-4 by this reaction.…”

“…To the best of our knowledge 3-azolylpyrazolo [5,1-c] [1,2,4]triazines are not described in the literature and reactions of β-azolyl enamines with diazo compounds and diazonium salts are not studied so far. At the same time both pyrazolotriazines and azoles, such as 1,2,3-thiadiazoles and isoxazoles, exhibit interesting biological and chemical properties.…”

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

“…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].…”