Synthesis of acyclic triarylmethane-based compounds containing perfluoropyridine subunits using 4,4′-(p-tolylmethylene)bis(2,6-dimethylphenol) as a flexible spacer

Abstract

To extend the synthetic applications of triarylmethanes, the nucleophilic aromatic substitution reactions of 4,4′-(p-tolylmethylene)bis(2,6-dimethylphenol) and various amines with pentafluoropyridine (PFP) were investigated. It was established that several parameters including the nature of nucleophiles, reaction conditions and molar ratio of reactants have significant effect on the selectivity of reactions. First, the nucleophilic aromatic substitution reaction of 4,4′-(p-tolylmethylene)bis(2,6-dimethylphenol), as a O,O-bidentate nucleophile, took place at C-4 position of PFP under mildly basic conditions and a triarylmethane (TRAM) containing two tetrafluoropyridine subunits was obtained in nearly quantitative yield. Second, the derived TRAM was submitted to the subsequent reactions with various amines under harsh conditions and a novel series of acyclic TRAM-based compounds containing functionalized perfluoropyridine subunits were obtained in high yields via the regioselective amination of tetrafluorpyridine subunits at C-2 and C-2′ positions.