Nucleophilic aromatic substitution fluoro derivative

Oxazolines (4) are easily prepared from benzoic acids and behave as activating groups in nucleophilic aromatic substitution. Thus, o-methoxy- or o-fluoro-substituents are replaced by the alkyl group of RLi. " The same oxazoline group in the 4-position of pyridine promotes 3-lithiation, whereas in the 3-position it induces nucleophilic alkylation to give 1,4-dihydropyridine derivatives. Benzyl alcohol is lithiated in the 2-position of the benzene nucleus. Solvent effects are suggested to be responsible for the quantitative syn selectivity in the alkylation of lithiated ketimines (5). ... 

The high performance characteristics of polyetherimide polymers and our desire to prepare them by an economically attractive scheme led us to explore several synthetic approaches. The key reaction in all of these was the formation of the diaryl ether linkage by a nucleophilic aromatic displacement reaction on suitably substituted (and activated) phthalic derivatives. Chloride displacement proceeded relatively slowly and gave polymers having only modestly high molecular weights. Fluoride displacement was quite facile, but processes based on the fluoro-deriviatives were economically unattractive. The synthetic and economic accessibility of appropriate nitro-substituted phthalic... 

Activation of aromatic compounds by transition-metal complexes was initially studied with Cr(CO)3 complexes. Nucleophilic addition of 2-lithio-l,3-dithianes to arene-chromium(O) complexes 185 followed usually by iodine-promoted decomplexation affords the corresponding 2-arylated 1,3-dithianes 186. The reaction of //-(toluene)- and (anisole)tricarbonylchromium (185) with compound 161 gave mixtures (52 46 and 10 90, respectively) of ortho and meta substituted derivatives (186) (Scheme 54)244. The meta directing effect was also observed (mainly better than 95%) with amino and fluoro substituted complexes245. 

It has been suggested that micellar catalysis could be exploited in analytical chemistry to increase the rate of derivative formation prior to spectroscopic measurement of the product [223, 224]. This has been attempted in the assay of amino acids and peptides following reaction with l-fluoro-2,4-dinitrobenzene (this undergoes aromatic nucleophilic substitution by amines to give arylated amines) [225]. For this reaction some amines require up to 20 min. In the presence of cetrimonium bromide, catalysis was achieved, although absorbances some 10% higher were obtained in the presence of surfactant. 

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