trans-and cis-2-Diazo-1- (4-alkylcyclohexyl) -1-ethanones were reacted with arenesulfonic acids to afford the corresponding 2- (4-alkylcyclohexyl) -2-oxoethyl arenesulfonates. The esteraseinhibitory activity and hypolipidemic effect of the arenesulfonates were examined, and it was found that in most cases, the trans-isomers were more active than the corresponding cis-isomers.Stereoselective syntheses of several biologically potent trans-isomers (trans-3) were also developed.