S NAr displacement of fluorine from pentafluoropyridin by sodium oximates: unprecedented substitution patterns

Selective C–H and C–F Bond Activation Reactions of Pyridine and Fluoropyridines – Formation of Binuclear μ‐X Titanocene Complexes (X = H, F) with α‐Functionalized N‐Heterocycles

“…Such compounds are very difficult to prepare by either electrophilic or nucleophilic substitution. [53,[57][58][59][60] …”

Recent trends in the Chemistry of fluorinated five and six‐membered heterocycles

“…Nucleophilic displacement reactions involving fluoroheterocyclic compounds and various nucleophiles have been reported [182][183][184][185][186][187][188]. For example, 2,6-difluoropyridine derivative 213 reacts with lithiated amines [184], alcohols [185], phenols [182] and thiophenols [182] to give a series of 2-substituted pyridines 215 [182].…”

“…The differences in 2-and 4-substitution ratios arise directly from the chelation stability in intermediate 219 [186]. Similarly, a series of pyridyl derivatives 223 could be prepared [184,[185][186][187][188].…”

Benzophenone O-(2,3,5,6-Tetrafluoro-4-pyridyl)oxime, Formed by 4-Substitution of Pentafluoropyridine by Benzophenone Oximate

“…The structure determination reported herein forms part of an investigation into the substitution of salts of hydroxylamines, oximes and hydrazones with pentafluoropyridine, in which novel competing 2-substitution was observed in addition to the expected 4-substitution (Banks, Jondi & Tipping, 1989;Jondi, 1989). The structural information was required to confirm that the 4-substituted product was the title oxime (1), and not the alternative immonium oxide (2), which would also aid identification of the 2-substituted product (3), for which crystals suitable for X-ray crystallographic analysis could not be obtained.…”