To complete the aim the known 4-R-5-t2-hydroxynaphthylazo)imidazoles 4a,b have been synthesized by the previously described method [5, 6]. In addition the new substituted hydroxynaphthylazoimidazoles 4b,d,e and 4-R-5-(5-R"-hydroxyphenylazo)imidazoles 7a-g were prepared by the coupling of the 5-diazoimidazoles 3a-e with 13-naphthol 5 and the p-substituted phenols 6a-c respectively in acetic acid.
has been studied. It was established that electron-withdrawing substituents at position 4 of the imidazole ring had a weak effect on the cyclization process. On the other hand, electron-donating substituents at positions 4 or 2 of this ring inhibited and in some cases completely prevented the formation of bicyclic products.Hydrazones are formed on azo coupling of diazoazoles with derivatives of cyanoacetic, malonic, and acetoacetic esters, and also acetylacetone, which are then cyclized into azolo[5,1-c][1,2,4]triazines. The cyclization reaction of hydrazones has been well ~ studied in the case of derivatives of pyrazole, 1,2,3-, and 1,2,4-triazole, and the results have been correlated in several reviews [1, 2]. Among imidazoles it has been reported for 5-diazoimidazole-4-carboxamide and 2-diazoimidazole [3][4][5][6].The aim of the present work was the synthesis of new derivatives of 4-amino-3-carbethoxyimidazo[5,1-c][1,2,4]triazine (I) and 3-cyanoimidazo[5,1-c][1,2,4]triazin-4(iH)-one (II), which are of interest as potentially biologically active compounds. It was also assumed that on obtaining these compounds by the cyclization of the corresponding substituted imidazolylhydrazones, data will be obtained on the effect of the character of the substituents in the imidazole ring on the course of this reaction. N~...,/R1 R~'~N tH
Hydrazones are obtained by coupling of diazoazoles with derivatives of ethyl cyanoacetate, diethyl malonate, ethyl acetoacetate, and acetylacetone. The obtained hydrazones depending on the reaction conditions, are cyclized to give azolo[5,l-c]-l,2,4-triazines or azolo[5,l-c]-l,2,4-triazoles. These reactions have been extensively studied for derivatives of pyrazole, 1,2,3-triazole, and 1,2,4-triazole [1][2][3]. In continuation of our wolk [4] on the study of imidazotriazines and their properties, the synthesis of bicyclic products containing nitro, chloro, bromo, mercapto, hydrazino, and acetylamino groups in the triazine ring seems to be of interest.The aim of the present work was the synthesis new derivatives of imidazo[5, l-c]-1,2,4-triazin-4(H)-one (I) and ethyl ester of imidazo[5, l-c]-l,2,4-triazole-3-carboxylic acid (11) as potential biologically active compounds. R R O EtOOC1 II I a,b R = CONH2, a R' = NOKb R I = CI, c,d R = CONHMe, c R t = NO2, d R t = C1, e-h R = COOEt, e R' = NO.,, fR I = C1, g R j = Br, h R ~ = NHCOMe, i-k R = NO_,, i R' = CI, j R' --Br,k R' = NHCOMc, I R = COOH, R t = NO2; II a R = CONHMe, b R = COOEt, c R = NO_, in order to synthesize these compounds using the procedures reported earlier [6-14], we prepared the known substituted 5-diazoimidazoles Illa-e. The azo coupling of the compounds IIIa-e with maionic acid derivatives Iva-d was carried out under conditions described in our previous work [4]. The azo compounds obtained cyclize in I% ethanolic KOH to give imidazotriazinones la-l. The cyclization of the compound V1 involved hydrolysis of the carboxazide group carboxyimidazotriazinone II.Pyrazolylazomalonate halides are converted into pyrazolotriazoles upon heating at reflux in benzene in the presence of triethylamine [5]. The cyclization of azo compounds Vd,g,j is not observed under analogous conditions. The synthesis of imidazotriazoles IIa-c was realized although in low yields upon the prolonged heating of azohalomalonates Vd,g,j in dimethylforuaamide with triethylamine. Nitro derivatives V could not be converted into imidazotriazolcs II under the same conditions.
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