Ethyl esters of alkanesulfonic acids, isethionic acid, trifluoromethanesulfonic acid, and 2, 2, 2-trifluoroethanesulfonic acid were synthesized and tested for inhibitory activity toward the growth of cultured leukemia L1210 cells. A quantitative correlation with the rate of hydrolysis and the capacity factor (partition property) was demonstrated by a multiple linear regression analysis; the more reactive and more lipophilic, the more cytotoxic they are. Interestingly, fluorine substitution on the alcoholic moiety resulted in remarkable deviations of the toxicity from those expected from the correlation found for the ethyl esters without fluorine substitution. Then, some fluorine derivatives of busulfan, a clinically used bifunctional sulfonate, were synthesized and tested. 2, 2-Difluoroethyl 2, 2, 2-trifluoroethanesulfonate was several times more cytotoxic than busulfan.
