Selective functionalization of 2-fluoropyridine, 2,3-difluoropyridine, and 2,5-difluoropyridine at each vacant position.
The concept of "regioexhaustive substitution" has been successfully applied to 2-fluoro-, 2,3-difluoro-, and 2,5-difluoropyridine. All vacant positions were amenable to regioselective metalation and subsequent carboxylation by employing either chlorine as a neighboring site activating protective group or trimethylsilyl as a neighboring site screening protective group. In this way, approximately half a dozen fluorinated pyridinecarboxylic acids were derived from each starting material.
Bobbio
Carla
C
Institute of Chemical Sciences and Engineering (ISIC-BCh), Ecole Polytechnique Fédérale, CH-1015 Lausanne, Switzerland.
Schlosser
Manfred
M