From Targeted Synthesis to Serendipitous Discovery: Transforming Perfluorotoluene into Discotic Liquid Crystals and Dearomatized Spirofluorenes
Abstract
This study develops a one-pot synthetic system that concurrently produces two classes of functional materials via a previously unobserved transformation of perfluorotoluene under nucleophilic conditions. Building on prior work with fluorinated discotic systems, the reaction of 2,2'-dilithio-1,1'-biaryls with perfluorotoluene (C₆F₅-CF₃) furnishes trifluoromethylated trifluorotriphenylene derivatives (TPFn, n = 1-4, 6, 8, 10, 8/2) alongside structurally distinct dearomatized spirofluorene analogues (TPFn-1). The formation of the spirofluorene compounds points to a competing pathway beyond classical aryl nucleophilic substitution. Based on structural evidences, a de-aromatization process involving cleavage of four C-F bonds (one from the pentafluorophenyl ring and three from the CF₃ group) and subsequent formation of new C-C bonds is proposed to account for the formation of the spiro-fused architecture. This side reaction sheds light on the moderate yields of the target TPFn series and highlights the complex reactivity of perfluorotoluene with 2,2'-dilithio-1,1'-biaryls. All TPFn compounds form thermally stable hexagonal columnar (Colhex) mesophases with large liquid-crystalline ranges, along with a strong modulation of the clearing temperatures with alkoxy chain-lengths. Despite the presence of the bulky lateral CF3 group, the transition temperatures are surprisingly not greatly affected when compared to previously synthesized 4F-TPn homologous compounds (with no CF3 groups). Structural analysis, supported by X-ray crystallography of di-tert-butyl model compound (tBuTPF), validates the molecular design and packing. This work thus provides a practical one-pot route to potentially fluorinated discotic semiconductors while revealing a competing transformation that advances the understanding of polyfluorinated arene chemistry and offers access to novel spiro-fused molecular architectures.
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BibTeX
@article{jian2026from,
title = {{From Targeted Synthesis to Serendipitous Discovery: Transforming Perfluorotoluene into Discotic Liquid Crystals and Dearomatized Spirofluorenes}},
author = {Jiao Jian and Ming-Mei Zhou and Wen-Hao Yu and Xiao-Yan Bai and Ke-Xiao Zhao and Ke-Qing Zhao and Bertrand Donnio},
journal = {Journal of Organic Chemistry},
year = {2026},
month = jun,
doi = {10.1021/acs.joc.6c00735},
url = {https://hal.science/hal-05807227v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - From Targeted Synthesis to Serendipitous Discovery: Transforming Perfluorotoluene into Discotic Liquid Crystals and Dearomatized Spirofluorenes
AU - Jiao Jian
AU - Ming-Mei Zhou
AU - Wen-Hao Yu
AU - Xiao-Yan Bai
AU - Ke-Xiao Zhao
AU - Ke-Qing Zhao
AU - Bertrand Donnio
PY - 2026
DA - 2026/06/29
JO - Journal of Organic Chemistry
DO - 10.1021/acs.joc.6c00735
UR - https://hal.science/hal-05807227v1
AB - This study develops a one-pot synthetic system that concurrently produces two classes of functional materials via a previously unobserved transformation of perfluorotoluene under nucleophilic conditions. Building on prior work with fluorinated discotic systems, the reaction of 2,2'-dilithio-1,1'-biaryls with perfluorotoluene (C₆F₅-CF₃) furnishes trifluoromethylated trifluorotriphenylene derivatives (TPFn, n = 1-4, 6, 8, 10, 8/2) alongside structurally distinct dearomatized spirofluorene analogues (TPFn-1). The formation of the spirofluorene compounds points to a competing pathway beyond classical aryl nucleophilic substitution. Based on structural evidences, a de-aromatization process involving cleavage of four C-F bonds (one from the pentafluorophenyl ring and three from the CF₃ group) and subsequent formation of new C-C bonds is proposed to account for the formation of the spiro-fused architecture. This side reaction sheds light on the moderate yields of the target TPFn series and highlights the complex reactivity of perfluorotoluene with 2,2'-dilithio-1,1'-biaryls. All TPFn compounds form thermally stable hexagonal columnar (Colhex) mesophases with large liquid-crystalline ranges, along with a strong modulation of the clearing temperatures with alkoxy chain-lengths. Despite the presence of the bulky lateral CF3 group, the transition temperatures are surprisingly not greatly affected when compared to previously synthesized 4F-TPn homologous compounds (with no CF3 groups). Structural analysis, supported by X-ray crystallography of di-tert-butyl model compound (tBuTPF), validates the molecular design and packing. This work thus provides a practical one-pot route to potentially fluorinated discotic semiconductors while revealing a competing transformation that advances the understanding of polyfluorinated arene chemistry and offers access to novel spiro-fused molecular architectures.
SN - 0022-3263
SN - 1520-6904
ER -