Abstract: The present invention provides anti-neoplastic topoisomerase I inhibitors of the formula: ##STR1## wherein Ar is (C.sub.6 -C.sub.12)aryl or (5- to 12-membered) heteroaryl comprising 1-3 N, S or non-peroxide O, wherein N is unsubstituted or is substituted with (C.sub.1 -C.sub.4)alkyl; X is H, CN, CHO, OH, acetyl, CF.sub.3, O(C.sub.1 -C.sub.4)alkyl, NO.sub.2, NH.sub.2, halogen or halo-(C.sub.1 -C.sub.4)alkyl; each Y is individually H, (C.sub.1 -C.sub.4)alkyl or aralkyl; Y' is H or (C.sub.1 -C.sub.4)alkyl; n is 0 or 1; and each Z is individually H, (C.sub.1 -C.sub.4)alkyl, halogen or halo(C.sub.1 -C.sub.4)alkyl; or a pharmaceutically acceptable salt therein.