Overcrowded 5,10,15‐Trisubstituted Derivatives: Synthesis of 5,10,15‐Tri(fluorenylidene)truxene

Sterically crowded 5,10,15‐triarylated truxenes are obtained by reaction of truxenetrione with aryllithium compounds (aryl = 1‐naphthyl, 2‐naphthyl, 9‐phenanthryl, 9‐anthracenyl), followed by reduction of the tertiary alcohols with Et3SiH and BF3. Base‐catalyzed isomerization of the anti derivatives provides syn‐5,10,15‐triarylated derivatives, with the exception of the 9‐anthracenyl that could not be isomerized. Overcrowded 5,10,15‐tri(fluorenylidene)truxene was also synthesized starting form the addition of fluorenyllithium to truxenetrione. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)