Synthesis of Tris‐ and Pentakis(triarylmethane) Compounds Bearing Perfluoropyridine Moieties from Functionalized Triarylmethane Precursors

Abstract The S N Ar reactions of 4,4′‐((( p ‐tolylmethylene) bis (2,6‐dimethyl‐1,4‐phenylene)) bis (oxy)) bis (2,3,5,6‐tetrafluoropyridine) 4 with hydroxybenzaldehydes 2a‐c were evaluated. Parameters such as reaction conditions, the molar ratio of reactants, and the nucleophilicity of hydroxybenzaldehydes played a crucial role in determining the selectivity of the reactions. The substitution of fluorines in precursor 4 occurred under harsh conditions, and the highest selectivity was observed for 3‐hydroxybenzaldehyde and 2‐hydroxybenzaldehyde, respectively. By optimizing the molar ratio of reactants and leveraging the higher nucleophilicity of the resulting potassium 3‐formylphenolates, along with the steric hindrance from potassium 2‐formylphenoxide, we successfully synthesized bis (oxy)benzaldehyde 9a′ and tetrakis (oxy)benzaldehyde 9c as the major products. Additionally, a new class of perfluorinated tris‐ and pentakis(triarylmethanes) 7a–c was synthesized through Friedel–Crafts arylation reaction of the derived (oxy)benzaldehydes 9 with veratrole 10a under silicotungstic acid catalysis. On the other hand, employing compound 4 as a triarylmethane spacer for the synthesis of novel (oxy)benzaldehydes and related triarylmethanes expands the synthetic utility of TRAMs. This approach not only provides a new application for TRAMs but also opens up the possibility of indirect fluorination of triarylmethanes.