9-Ethyl-3-{6-(het)aryl-[1,2,5]oxadiazolo[3,4-b]pyrazin-5-yl}-9H-carbazoles: synthesis and study of sensitivity to nitroaromatic compounds

5-(9-Ethyl-9H-carbazol-3-yl)-substituted 6-(het)aryl[1,2,5]oxadiazolo[3,4-b]pyrazines were synthesized by direct transition metal-free CH functionalization in the pyrazine ring. Their photophysical and sensory properties with respect to nitrobenzene and 2,4-dinitrotoluene vapors were studied using a Nitroscan portable detector of nitro-explosive substances (Ekaterinburg, Russia).