Illudin S and illudin M are extremely cytotoxic sesquiterpenes produced in cultures of basdiomycete Omphalotus illudins. Some of the analogues of illudins have been found to be quite effective at inhibiting tumor growth, while the others are not. These analogues also have drastically reduced cytotoxicity. Aza analogues of illudins which can be prepared by cycloaddition-rearrangement processes. Exact geometries and structural properties of these newly or previously synthesized compounds are not yet known. In this study, structure-activity relationships of these analogues have been investigated. Structures of these compounds were predicted by using B3LYP density functional method and 6-31G* basis set. Antitumor activity data are reported in several articles. Structure-activity correlations were carried out by comparing the activity data and the structural properties. (C) 2001 Elsevier Science B.V. All rights reserved.