Process for the preparation of 1,2,3,9-tetrahydro-9-methyl-3-{(2-methyl-1H-imidazol-1-yl)methyl}-4H-carbazol-4-one

A method of preparing 1,2,3,9-tetrahydro-9-methyl-3-[(2-methyl-1H-imidazol-1-yl)methyl]-4H-carbazol-4-one of formula (I) or a pharmaceutically acceptable salt thereof which comprises reacting 1,2,3,9-tetrahydro-9-methyl-4H-carbazol-4-one of formula (II) with a 2-methylimidazole derivative of formula (III) in an organic solvent or in a mixture of an organic solvent and water, in the presence of a halosilane compound:

• wherein R1 is N,N-dimethylamino, N,N-diethylamino, N,N-dipropylamino, morpholin-4-yl, piperidin-1-yl or pirrolidin-1-yl.