Abstract

Starting from six industrially available fluorinated pyridines, an expedient access to all three tetrafluoropyridines, all six trifluoropyridines, and the five non-com. difluoropyridines was developed. The methods employed for the selective removal of fluorine from polyfluoropyridines were the redn. 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. [on SciFinder (R)]

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