Fusion of Aza‐ and Oxadiborepins with Furans in a Reversible Ring‐Opening Process Furnishes Versatile Building Blocks for Extended π‐Conjugated Materials

Abstract

A modular synthesis of both difurooxa-and difuroazadiborepins from a common precursor is demonstrated. Starting from 2,2'-bifuran, after protection of the positions 5 and 5' with bulky silyl groups, formation of the novel polycycles proceeds through opening of the furan rings to a dialkyne and subsequent re-cyclization in the borylation step. The resulting bifuran-fused diborepins show pro-nounced stability, highly planar tricyclic structures, and intense blue light emission. Deprotection and transformation into dibrominated building blocks that can be incorporated into π-extended materials can be performed in one step. Detailed DFT calculations provide information about the aromaticity of the constituent rings of this polycycle.

Doping Heptagon‐Containing π‐Conjugated Systems with Boron

“…Later, they expanded this modular synthesis to access the furans-fused azadiborepins and oxadiborepins. [23] In the case of the furan-and thiophene-based compounds, the positions 5 and 5' could be substituted with bulky silyl groups, which could be removed on a later stage, and this could be used to prepare compounds with an extended π-conjugated backbone. Wagner group reported another Ni-mediated intramolecular Yamamoto rearrangement reaction in THF to prepare oxadiborepin, where the reaction selectivity between borondoped tetrabenzopentacene and oxadiborepin is determined by the reaction solvent.…”

Heteroatom-boron-heteroatom-doped π-conjugated systems: structures, synthesis and photofunctional properties

“…However, the BXB-doped p-conjugated systems are out of the scope of this Feature article. [14][15][16][17][18] 2. NBN-doped p-conjugated systems N-B-N unit originally is exploited to increase the chemical and thermal stabilities of the zigzag-edged PAHs and nanographenes.…”

Synthesis, Structure, and Properties of Monodispersed and Highly Luminescent Organoborane Oligomers

“…Zhou and co-workers synthesized BN-embedded oligomers with multiple pairs of BN units up to four by electrophilic borylation in the same year. 16 In 2022, Helten and co-workers modularized the synthesis of difurooxa-and difuroazadiborepins with 2,2′-bifuran as the starting material; these two bifuran-fused diborepins show pronounced stability, highly planar tricyclic structures, and intense blue light emission. 17a In addition, Helten and coworkers prepared the first oligo-and poly-(furylborane)s, 17b,c and they also prepared oligoiminoboranes with an average of up to 18 chain-like BN units by Si/ B 18a,b and Sn/B exchange polycondensation.…”