Synthesis, spectroscopic and crystallographic study of some carbamates from an azabicyclic chloroformate and primary heterocyclic amines

A series of benzimidazole, thiazole and benzothiazole carbamates derived from 9-methyl-9-azabicyclo[3.3.1]nonan-3beta-ol was synthesized and studied by H-1, C-13, 2D NMR and IR spectroscopy. The crystal structure of N-(benzimidazol-2-yl)-9-methyl-9-azabicyclo[3.3.1]nonan-3beta-yl-carbamate (8) was determined by X-ray diffraction. It has been found that two different carbamates can be obtained in the case of the benzimidazole derivatives. The structure of the studied compounds corresponds to the amino form of the molecules and show different types of hydrogen bonds. In CDCl3 solution all the carbamates displayed a preferred flattened chair-chair conformation similar to that observed for compound 8 in the solid state.