1-amino-1,3,3,5,5-pentamethylcyclohexane (Neramexane) and pharmaceutically acceptable salts thereof are valuable agents for the continuous therapy of patients suffering from diseases and conditions such as tinnitus, and nystagmus.
Methods of preparing these agents are known.
In one method, commercially available isophorone is converted to Neramexane in a reaction sequence comprising five steps according to the following reaction scheme (W. Danysz et al., Current Pharmaceutical Design, 2002, 8, 835-843):

In the first step of the sequence (step (i)), isophorone 1 is converted to 3,3,5,5-tetramethylcyclohexanone 2 by CuCl-catalyzed conjugate addition of methyl-magnesium iodide.
In the second step (step (ii)), 3,3,5,5-tetramethylcyclohexanon 2 is converted to 1,3,3,5,5-pentamethylcyclohexanol 3 by Grignard reaction with methylmagnesium iodide.
Danysz discloses that compound 3 has been prepared according to the method of reference [4] (Chiurdoglu). This reference discloses the reaction of 3,3,5,5-tetramethylcyclohexanone with methylmagnesium bromide to the respective cyclohexanol. Page 377, section 5 discloses that compound 3 has been subjected to distillation (boiling point 91 to 92° C. at 22 torr), i.e. it has been purified. Accordingly, compound 3 as used by Danysz is purified.
In the third step (step (iii)), said cyclohexanol 3 is converted to 1-chloroacetamido-1,3,3,5,5-pentamethylcyclohexane 6 by chloroacetonitrile in a Ritter reaction.
Danysz discloses that compound 6 has been prepared according to the method of reference [6] (Jirgensons). This reference discloses the Ritter reaction of the cyclohexanol with chloroacetonitrile to the respective amide (Scheme on page 1709, compound 1a, compound 2a). According to the general reaction procedure, the resulting amide is subjected to a Kugelrohr short path distillation, i.e. it has been subjected to a purification step (page 1710, right column, first and second paragraph). Accordingly, compound 6 as used by Danysz is purified.
In the fourth step (step (iv)), subsequent cleavage of the chloroacetamido group in amide 6 with thiourea, and acidification of the resulting amine with hydrochloric acid in the fifth step (step (v)) of the reaction sequence results in Neramexane (1-amino-1,3,3,5,5-pentamethylcyclohexane) 7 in the form of its hydrochloride.