Compound can be prepared in three steps starting from (-)-scopalamine (hyoscine) (I) by demethylation of (-)-scopolamine with phosgene or potassium permanganate, by alkylation of the resulting (-)-norscopolamine (II) with ethylbromide (A) by means of sodium carbonate, and by quaternization of the resulting (-)-N-ethyl-norscopolamine (III) with methylbromide yielding Ba-253-BR.