Synthesis, structural, conformational and pharmacological study of some carbamates derived from 8-methyl-8-azabicyclo[3.2.1]octan-3α-ol

A series of benzimidazole, thiazole, and benzothiazole carbamates derived from 8-methyl-8-azabicyclo[3.2.1]octan-3α-ol hydrochloride was synthesized and studied by 1H, 13C NMR and IR spectroscopy. To assist in the interpretation of the spectroscopic data, the free bases were obtained and studied by IR spectroscopy in different media.As in related compounds, spectroscopic results showed that two different carbamates (1-carbamate or 2-carbamate) could be obtained in the case of the hydrochlorides of benzimidazole derivatives.The hydrochlorides studied displayed in DMSO-d6 solution a preferred flattened chair-envelope conformation with the NCH3 substituent in an equatorial disposition.Pharmacological assays in vitro and in vivo were drawn to evaluate 5-HT3 activity.

► Synthesis of a series of tropanyl benzimidazole, thiazole and benzothiazole carbamates.
► Structure is deduced using NMR, IR spectroscopy and X-ray diffraction.
► For benzimidazole derivatives, 1-carbamate and 2-carbamate have been obtained.
► Compounds show pharmacological activity as 5-HT3 antagonists.