Selective Synthesis of Perfluoroalkylated Corannulenes and Investigation of their Structural, Dynamic and Electrochemical Behavior

Abstract

Herein we report general methods allowing the synthesis of various perfluoroalkylated corannulenes with a specific substitution pattern. Variable temperature NMR spectroscopic investigations revealed dynamic behavior which was analyzed by line shape analysis. The activation parameters of these dynamic processes were determined. For a tetrasubstituted compound it was possible to observe through space scalar coupling. The packing motifs were elucidated by X-ray crystallography, showing that the substitution pattern as well as the size of substituents strongly influence intermolecular π-stacking. The reduction potentials of the perfluoroalkylated compounds were determined by cyclic voltammetry.

Corannulenes with Electron‐Withdrawing Substituents: Synthetic Approaches and Resulting Structural and Electronic Properties

“…For this strategy, norbornadiene is replaced by other dienophiles, for example, fluorinated alkynes. Using this methodology, a variety of fluorinated fluoranthene‐derivatives are accessible in a selective fashion (Scheme ) . This also includes pentafluorosulfanyl‐substituted 13 g .…”

“…A little more variety is introduced by using diiodoacetylene as a dienophile to yield diiodofluoranthene 16 (Scheme ) . The iodo substituents can selectively be substituted by using a perfluoroalkyl/copper/zinc system originally developed by Mikami to yield disubstituted fluoranthenes with longer perfluoroalkyl chains.…”

“…Nevertheless, all the subsequent steps of bromination and cyclization towards disubstituted corannulenes have to be performed for every single derivative. ortho ‐Disubstituted (perfluoroalkyl)corannulenes 15 h and 15 j are accessible by this synthetic route, even if the yields are very poor (Scheme ) …”

“… Synthesis and derivatization of diiodofluoranthene 16 to yield bis(perfluoroalkyl)corannulenes 15 h and 15 j . DMPU=1,3‐dimethyl‐3,4,5,6‐tetrahydropyrimidin‐2(1 H )‐one.…”

“…Similar to Siegel's approach, halocorannulenes can also be perfluoroalkylated by using Mikami's copper/zinc system, as it is performed for the substitution of diiodofluoranthene 16 (compare Scheme ). Using this reagent, tetrabromocorannulene 2 is pentafluoroethylated under microwave irradiation to yield fourfold‐substituted 19 a in a moderate yield (Scheme ) . Along with (pentafluoroethyl)corannulene 19 , threefold‐substituted isomers 20 a and 20 b are obtained as minor products.…”