Synthesis, structural and crystallographic study of some carbamates derived from 9-methyl-9-azabicyclo[3.3.1]nonan-3α-ol

A series of benzimidazole, thiazole and benzothiazole carbamates derived from 9-methyl-9-azabicyclo[3.3.1]nonan-3alpha-ol was synthesized and studied by H-1, C-13, 2D NMR and IR spectroscopy. To assist in the interpretation of the spectroscopic data, the crystal structure of 3 (9-methyl-9-azabicyclo[3.3.1]nonan-3alpha-yl 2-amino-1H-benzimidazole-1-carboxilate) was determined by X-ray diffraction. It has been found that 1-carbamates and 2-carbamates can be obtained in the case of the benzimidazole derivatives. The benzimidazole-1-carbamates are obtained in higher yields (41, 38%) than the benzimidazole-2-carbamates (3, 9%). The compounds studied displayed in CDCl3 solution a preferred chair-boat conformation with the substituted ring in a distorted boat form and the N-CH3 substituent in an axial position with respect to the chair piperidine ring. This conformation is similar to that determined by X-Ray diffraction for compound 3. (C) 2004 Elsevier B.V. All rights reserved.