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Removal of Fluorine from and Introduction of Fluorine into Polyhalopyridines: An Exercise in Nucleophilic Hetarenic Substitution
Author(s) -
Bobbio Carla,
Rausis Thierry,
Schlosser Manfred
Publication year - 2005
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400837
Subject(s) - fluorine , nucleophilic substitution , substitution (logic) , nucleophilic aromatic substitution , chemistry , substitution reaction , medicinal chemistry , organic chemistry , computer science , programming language
Starting from six industrially available fluorinated pyridines, an expedient access to all three tetrafluoropyridines ( 2 – 4 ), all six trifluoropyridines ( 5 – 10 ), and the five non‐commercial difluoropyridines ( 11 – 14 and 16 ) was developed. The methods employed for the selective removal of fluorine from polyfluoropyridines were the reduction by metals or complex hydrides and the site‐selective replacement by hydrazine followed by dehydrogenation–dediazotation or dehydrochlorination–dediazotation. To introduce an extra fluorine atom, a suitable precursor was metalated and chlorinated before being subjected to a chlorine/fluorine displacement process.