One-pot synthesis of dicyclopenta-fused peropyrene via a fourfold alkyne annulation

Abstract

A novel dicyclopenta-fused peropyrene derivative 1 was synthesized via a palladium-catalyzed four-fold alkyne annulation of 1,3,6,8-tetrabromo-2,7-diphenylpyrene (5) with diphenylacetylene. The annulative π-extension reaction toward 1 involved a twofold [3 + 2] cyclopentannulation and subsequent twofold [4 + 2] benzannulation. The structure of 1 is unambiguously confirmed by X-ray crystallography; 1 adopted a twisted geometry due to the steric hindrance of the phenyl rings and the hydrogen substituents at the bay regions. Notably, compound 1 exhibits a narrow energy gap (1.78 eV) and a lower LUMO energy level than the parent peropyrene without the fusion of the five-membered rings. In addition, the effects of the peri-fused pentagons on the aromaticity and molecular orbitals of 1 were evaluated by theoretical calculations. This work presents an efficient method to develop π-extended aromatic hydrocarbons with cyclopenta moieties.

Tetrasubstituted Peropyrenes Formed by Reductive Aromatization: Synthesis, Functionalization and Characterization

“…The most twisted representative is a tetranaphthyl annulated peropyrene built up via oxidative Scholl dehydrogenation of a tetranaphthyl‐diphenylbenzene precursor reported by the group of Miao (Scheme 2b) [32] and later extended with pyrene functionalities by Feng [33] . Recently, these authors also accessed a dicyclopenta‐fused peropyrene via alkyne annulation approach [34] …”

“… [33] Recently, these authors also accessed a dicyclopenta‐fused peropyrene via alkyne annulation approach. [34] …”

“…[33] Recently, these authors also accessed a dicyclopenta-fused peropyrene via alkyne annulation approach. [34] Since many peropyrene syntheses require low-yield aromatization steps or multistep synthesis approaches, we aimed to establish a higher yield synthetic approach with only a short number of steps. Thereby we were able to obtain peropyrenes with a yet undescribed 1,3,8,10-substitution pattern.…”

On‐surface synthesis of porous graphene nanoribbons containing nonplanar [14]annulene pores

“…The synthesis of monomer 1 was carried out in solution as displayed in Scheme 1. First, 2,7‐bis(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl)pyrene ( 3 ) was prepared using an iridium‐catalyzed borylation of the commercially available pyrene ( 2 ) according to the reported procedure 10 . Subsequently, the key intermediate 5 was synthesized in 17% yield through the twofold annulative π‐extension reaction 11 with 5,5‐dimethyl‐5 H ‐dibenzo[ b , d ]silole ( 4 ) in 1,2‐dichloroethane at 80 °C in the presence of Pd(CH 3 CN) 4 (SbF 6 ) 2 catalyst and o ‐chloranil.…”

“…First, 2,7-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)pyrene (3) was prepared using an iridium-catalyzed borylation of the commercially available pyrene (2) according to the reported procedure. 10 Subsequently, the key intermediate 5 was synthesized in 17% yield through the twofold annulative π-extension reaction 11 with 5,5-dimethyl-5H-dibenzo[b,d] silole (4) in 1,2-dichloroethane at 80 C in the presence of Pd(CH 3 CN) 4 (SbF 6 ) 2 catalyst and o-chloranil. After that, compound 5 was treated with copper(II) bromide (CuBr 2 ) for 24 h at 95 C to afford the DBHBT (1) with a yield of 40%.…”