trifluoromethylsulhonyl halogenide or an isocyanate or thioisocyanate of the formula r 16 u2014 n u2550 c u2550 o or r 16 u2014 n u2550 c u2550 s wherein r 16 is as previously defined h alkylating a dihydroindole derivative of the formula x with an alkylating derivative of the formula xi wherein r 2 r 8 x y a n m w and the dotted line are as previously defined and l is a leaving group such as eg halogen mesylate or tosylate or wherein r 2 r 8 x y a n w and the dotted line are as previously defined and m is 1 2 3 4 or 5 whereupon the compound of formula i is isolated as the free base or a pharmaceutically acceptable acid addition salt thereof the reaction in methods f and g are conveniently performed at low temperature eg below room temperature in an inert solvent such as acetone dichloromethane tetrahydrofuran or dimethoxyethane when reactive carboxylic acid chlorides isocyanates or isothiocyanates are used formylated amines are prepared from the corresponding amines by reaction in formic acid with esters of formic acid or by reaction with mixed formic acid anhydride prepared in situ generally reaction temperatures are between 0 u00b0 c and the boiling point of the formyl precursor compounds the alkylations according to methods a and h are generally performed by refluxing in a suitable solvent such as acetone methyl isobutyl ketone tetrahydrofuran dioxane ethanol or 2 propanol in the presence of a base such as triethylamine or potassium carbonate the reductions of double bonds according to methods d and e are generally performed by catalytic hydrogenation at low pressure lt 3 atm.