Indeno[2,1??b]indol??6??ones are an interesting class of compounds structurally related to ellipticine,11. Goodwin , S. , Smith , AF and Horning , EC 1959. Alkaloids of Ochrosia elliptica. J. Am. Chem. Soc., 81: 1903–1908. [CrossRef], [Web of Science ®] View all references a natural alkaloid characterized by a significant antitumor activity.22. Dalton , LK , Demerac , S. , Elmes , BE , Loder , JW , Swan , JM and Telei , T. 1967. Synthesis of the ...