2-(2-Alkylamino-4-aminothiazol-5-oyl)-N-mcthylbenzimidazoles: Synthesis and the effect of intra molecular H-bonding in ~1H NMR

摘要

2-(2-Alkylamino-4-aminothiazol-5-oyl)-N-methylbenzimida-zoles, as the analogs of the cytotoxic marine alkaloid dendrodoine, is synthesized and characterized by elemental analysis, 1R, NMR and mass spectral data. The thiourea derivatives provide four ring atoms for the thiazole ring construction and thus act as [C-N-C-S] synthons. The remaining carbon of the thiazole is sourced from 2-(2-bromoacctyl)-N-methylbenzimidazolc. This [~(4+)1] heterocyclization reaction is adopted for the synthesis of novel benzimidazole derivatives. The presence of two signals in the 'H NMR spectrum arising from the NH2 hydrogens shows that the two hydrogens are not exchanging rapidly on the chemical shift time scale and they are in two different chemical environments due to H-bonding.