The present invention provides the S enantiomer of a compound of formula I ##STR00001## wherein R.sup.1 represents chloro, trifluoromethyl or trifluoromethoxy, R.sup.2 represents H or fluoro and R.sup.3 represents a C.sub.2-4alkyl group as well as pharmaceutically acceptable salts, solvates 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.