Sinteza i spektroskopska karakterizacija novih N-supstituiranih derivata benzimidazola

This work presents the synthesis of novel potentially biologically active N-substituted benzimidazole derivatives 8–10 and 20–22 and 2-benzimidazolyl-substituted acrylonitrile 49. Novel compounds were prepared by classical reactions of organic chemistry and by microwave assisted reactions. Corresponding main precursors, N-substituted 5-cyano-2-cyanomethylbenzimidazoles 8–10, N-substituted 2-cyanomethylbenzimidazoles 20–22 and 2-cyanomethyl-5(6)-piperidinyl-benzimidazole 47 were prepared by using multi-step linear synthesis. Acrylonitrile derivatives with cyano group on the benzimidazole nuclei 12–14 were prepared by aldol condensation of N-substituted 5-cyano-2-cyanomethylbenzimidazoles 8–10 and 4-N,N-dimethyl-aminobenzaldehyde 11. Compounds 13 and 14 were isolated as E-isomers while compound 12 was isolated as a mixture of two geometric isomers in a 1 (12b): 3 (12a) ratio. Acrylonitrile derivatives 31–43 were prepared by aldol condensation of N-substituted 2-cyanomethylbenzimidazoles 20–22 with corresponding aromatic and heteroaromatic aldehydes 23–30. Compounds 32 and 34–43 were isolated as E-isomers while compounds 31 and 33 were isolated as a mixture of two geometric isomers in a 1 (31b): 2 (31a) and 1 (33b): 5 (33a) ratio. Piperidinyl-substituted acrylonitrile derivative 49 was prepared by aldol condensation of 2-cyanomethyl-5(6)-piperidinylbenzimidazole and 4-N,N-dimethylaminobenzaldehyde as a mixture of two tautomers 49a and 49b. The structures of all compounds were determined by means of 1H and 13C NMR spectroscopy as well as mas spectrometry.