A process is described for the preparation of a precursor alcohol of (±)-2-[thienyl(1-methyl-1 H -pyrazol-5-yl)methoxy]- N , N dimethyletanamine and in general for thyenylazolylalcoxyethanamines and their enantiomers. It comprises the asymmetric reduction of a prochiral ketone in the presence of a chiral ruthenium (II) catalyst system comprising at least a bidentate phosphorous-containing ligand and a diamine ligand to render chiral alcohols. The chiral alcohols are further O-alkylated to render the corresponding pharmaceutically active ethanamines.