Abstract: Organoselenones of the formulaR.sub.1 --Se(O.sub.2)--(CH.sub.2).sub.n --Xwherein R.sub.1 is selected from the group consisting of aryl, vinyl, acetylenyl, and aralkyl, n is an integer equal to 2 to 6 and X is a leaving group selected from the group consisting of halides, sulfonates and selenones; were surprisingly found to be useful as alkylating agents which possessed a high degree of selectivity for nitrogen nucleophiles without the usual increased preference for sulfur nucleophiles. This property allows the effective use of these compounds as anti-cancer alkylating agents suitable for use in drug-resistant cell lines which display either thiol mediated drug resistance or MER(+)-mediated drug resistance. Two methods of synthesizing these compounds are also provided.