Diversity-oriented synthesis of tetrathia[8]circulenes by sequential C–H borylation and annulation

Abstract

We have succeeded in the diversity-oriented synthesis of tetrathia[8]circulenes by sequential C-H borylation and annulation from cyclic tetrathiophene, and time-resolved microwave conductivity studies have proved that the intrinsic hole mobilities of tetrathia[8]circulenes are dependent on the chain length of the alkyl substituents at the peripheral positions.

Synthesis of Tetrasilatetrathia[8]circulenes by a Fourfold Intramolecular Dehydrogenative Silylation of C−H Bonds

“…We found that the simulated absorption spectrum was consistent with the experimental one (Figures a and S5 in the Supporting Information), and these results clearly suggest that the lowest energy band of 1 a at 350–400 nm has a symmetry forbidden nature (Figure a and Table S3 in the Supporting Information) . In sharp contrast, we have previously reported that the lowest‐energy absorption bands in tetrathia[8]circulenes were observed in the 350–450 nm region . The significant change in the absorption spectra of 1 and tetrathia[8]circulenes is considered to be caused by the difference of the symmetric feature and the annulation modes.…”

“…For example, tetraoxa[8]circulenes, diazadioxa[8]circulenes, and tetrabenzotetraaza[8]circulene have been successfully prepared as core frameworks incorporating four benzene rings with four heteroaromatic rings (Scheme ). Very recently, Wong's group and we have independently reported the synthesis of tetrathia[8]circulenes and tetraselena[8]circulene …”

“…We then designed a new synthetic route toward 1 based on the sequential introduction of Si−H groups and a subsequent intramolecular cyclization (Scheme ). The key building block of this strategy is tetraboryltetrathienylene 3 , which was obtained from the iridium‐catalyzed direct C−H borylation of 2 . Treatment of 3 with six equivalents of N ‐iodosuccinimide (NIS) in the presence of six equivalents of CuI at 80 °C gave the corresponding tetraiodotetrathienylene 4 in 89 % yield after three hours .…”

“…[2] Recently,aseries of [8]circulenesi ncorporating heteroaromatic rings, that is, hetero[8]circulenes, have attractedc onsiderable attention as organic electronic materials for light-emitting diodes and field-effect transistors on the basis of their highly rigids tructures ande ffectivee lectronic perturbation of the heteroatoms.F or example, tetraoxa[8]circulenes, [3] diazadioxa[8]circulenes, [4] and tetrabenzotetraaza[8]circulene [5] have been successfully prepared as core frameworks incorporating four benzene rings with four heteroaromatic rings (Scheme1). Very recently,W ong'sg roup and we have independently re-portedt he synthesis of tetrathia[8]circulenes [6,7] and tetraselena[8]circulene. [6] Hetero[8]circulenes annulated by eight heteroaromatic rings can be considered as an [8]radialene bridged by eight heteroatoms.…”

Sequential N‐Alkylations of Tetrabenzotetraaza[8]circulene as a Tool To Tune Its Optical Properties

“…in 2013; in the solid state 1 was found to have a saddle‐shaped conformation. In contrast, hetero[8]circulenes such as oxa[8]circulene 2 , thia[8]circulene 3 ,, and selena[8]circulene 4 have been prepared and found to display rather planar structures. We have recently reported a “fold‐in”‐type oxidative synthesis of tetrabenzotetraaza[8]circulene AC , which displays a quite planar structure and sharp absorption and emission spectra characteristic of polycyclic aromatic hydrocarbons .…”