Synthesis and biological activity of new 1H-Pyrazolo[3,4-b]quinoxalines (flavazoles)

Abstract

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Chemoselectivity in reactions of hydrazonoyl halides with ethyl 2(3H)‐permidinylideneacetate

“…The spectra of the compounds in dioxane showed in each case two absorption bands in the regions 470-419 and 344-320 nm ( Table 1). This absorption pattern is similar to that reported for the azo chromophore [19,20]. Also, the electronic absorption spectra of compound 9c, taken as a typical example of the series prepared, in different solvents showed little, if any, shift (Table 1).…”

Microwave‐Assisted Synthesis of Antimicrobial Agents Containing Carbazole and Thiazole Moieties

“…Figure indicates that the isolated product 6a – f can exist in four tautomeric forms 6A – D ; their electronic absorption spectra were studied in dioxane and showed the largest values of wavelength λ max of derivatives 6a – f at 598–468 nm (Table ). This absorption pattern is similar to that reported for the azo chromophore . Such data discarded the hydrazone form 6D whereas the 1 H NMR of the isolated products 6a – f discarded the tautomeric structure 6C owing to the presence of singlet signal at δ 8.80–8.53 ppm for the CH═N.…”

Site‐ and Regioselectivity of the Reaction of Hydrazonoyl Chlorides with Perimidine Ketene Aminal. Antimicrobial Evaluation of the Products

“…As shown, each of the compounds 8 in dioxane exhibits two characteristic absorption bands in the regions λ max 485–465 and 342–336 nm. Such an absorption pattern is similar to that of typical azo chromophore . Furthermore, the spectrum of 8c , taken as a typical example of the series studied, in solvents of different polarities showed little, if any, shift (Table ).…”