Starting from formylphenols 2 (2a = 4-formylphenol, 2b = 4-formy1-2-methoxyphenol or vanillin, 2c = 4-formyl-2etboxyphenol or ethylvanillin, 2d = 2,6-dimethoxy-4-fonrrylphenol or syringaldehyde, 2e = 3-formy1-6-methoxyphenol or isovanillin) the corresponding phenoxides 3a-e were synthesized. These, in the presence of the crown ethers (15C5 or 18C6) and 4-chloro-7-nitrobenzofurazan (5), lead to the corresponding 4-(4′-formylaryloxy)-7-nitrobenzofurazanes 1 (1a = 4-(4′-formylphenoxy)-7-nitrobenzofurazan, 1b = 4-(4′-formy1-2′-methoxyphenoxy)-7-nitrobenzofurazan, 1c = 4(2′-ethoxy-4′-formylphenoxy)-7-nitrobenzofurazan, Id = 4-(2′ ,6′-dimethoxy-4′-formylphenoxy)-7-nitrobenzofurazan, 1′e = 4-(4′-formyl-1′-methoxyphenoxy)-7-nitrobenzofurazan). The structures of the new compounds 1a-e were confirmed by 1H- and 13C-NMR. The hydrophobicity of compounds 1 was described by RPTLC which decreases in the following order: 1c> Id = 1e> 1a = 1b;> the compounds 1a-e are more hydrophilic than their analogs which do not contain the formyl group. In the presence of aminoacids and their derivatives (peptides, proteins, etc.) the solutions of the compounds 1a-e show immediately a strong fluorescence.