The present invention provides the S enantiomer of a compound of formula (I); wherein R.sup.1 represents 2,4-difluorophenyl or cyclohexyl as well as pharmaceutically acceptable salts, solvates, crystalline forms and prodrugs thereof, to processes for preparing such compounds, to their the utility in treating clinical conditions including lipid disorders (dyslipidemias) whether or not associated with insulin resistance, to methods for their therapeutic use and to pharmaceutical compositions containing them.