Skeletal Rearrangement of Twisted Polycyclic Aromatic Hydrocarbons under Scholl Reaction Conditions

Treatment
of a twisted polycyclic aromatic hydrocarbon containing
cyclooctatetraene fused by two 9,9′-bifluorenylidene units
under the Scholl reaction conditions (FeCl3 or 2,3-dichloro-5,6-dicyano-1,4-benzoquinone
and scandium trifluoromethanesulfonate) led to stepwise skeletal rearrangements
to afford initially a hydrocarbon with a seven-membered ring and then
tetrabenzo­[a,d,j,m]­coronene with all six-membered rings. The course
of the rearrangement was interpreted in terms of the acid-catalyzed
isomerization of 9,9′-bifluorenylidene into dibenzo­[g,p]­chrysene moieties on the basis of theoretical
investigations.

在肖尔反应（Scholl reaction）条件下，以三氯化铁（FeCl₃）或2,3-二氯-5,6-二氰基-1,4-苯醌与三氟甲磺酸钪为反应试剂，对含有经两个9,9'-联芴亚单元稠合的环辛四烯结构的扭曲多环芳烃进行处理，可引发逐步骨架重排：首先生成含七元环的烃类产物，随后得到全为六元环结构的四苯并[a,d,j,m]晕苯。基于理论研究，该重排过程可通过9,9'-联芴经酸催化异构化为二苯并[g,p]䓛结构单元的路径加以阐释。