Chemical Carcinogenesis : Syntheses of 2,7- Bis- (Acetamido) Fluorenes with Increased Molecular Thickness by 9-Substitution

The series: 9-methyl, 9-isopropyl, 9-cyclohexyl, 9,9-dimethyl, 9,9-diethyl, and the unsubstituted parent 2,7-bis (acetamido) fluorene were synthesized from the corresponding 9-substituted fluorenes. The two routes employed consisted of either (1) dinitration, reduction to the diamine, and diacetylation, or (2) Friedel-Crafts diacylation, then rearrangement via the Schmidt reaction. This provides a series of compounds of use in comparing relative carcinogenicity with changes in chemical reactivity as a function of increased steric hindrance due to altered molecular "thickness." Preliminary to a study of the donor characteristics in charge-transfer complex formation of potentially carcinogenic compounds, we have synthesized a series of 9-substituted-2,7-bis (acetamido) fluorenes. The parent, 2,7-bis (acetamido) fluorene (fig. 1) should be coplanar by analogy with the hydrocarbon, fluorene (Brown and Figure 1. 2,7-bis (acetamido) fluorene.