The present invention relates to compounds of formula I, ##STR00001## their pharmaceutically acceptable salts as well as their enantiomeric forms, diastereoisomers and racemates; the preparation of the above-mentioned compounds, medicaments containing them and their manufacture, as well as the use of the above-mentioned compounds as inhibitors of histone deacetylase (HDAC) and therefore in the control or prevention of illnesses and disorders as mentioned above, or in the manufacture of corresponding pharmaceutical compositions.