The organometallic approach to the functionalization of arenes and heteroarenes has recently been investigated by our group introducing modifications of the standard methods. This includes, in particular, the basicity-driven heavy halogen migration, which ...
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 fluo ...
Deprotonation-triggered heavy halogen migrations should become a favorite tool in arene synthesis if their occurrence and outcome could be made predictable. Particularly attractive, though extremely rare, are stop-and-go situations where a first intermedia ...
2,4-Difluoropyridine, 2,4-dichloropyridine, 2,4,6-trifluoropyridine, 2,4,6-trichloropyridine and 2,3,4,6-tetrafluoropyridine react with std. nucleophiles exclusively at the 4-position under halogen displacement. However, the regioselectivity can be complet ...
The relative displacement rates of the halide substituent from 2-fluoro- and 2-chloropyridines by EtONa in EtOH at +25 Deg were assessed by competition kinetics. The 2-fluoropyridine reacts 320 times faster than the chloro analog. A CF3 group increases the ...
2,4-Difluoro-, 2,4,6-trifluoro-, and 2,3,4,6-tetra(fluoro)pyridine undergo nucleophilic substitution preferentially if not exclusively at the 4-position. However, after the introduction of a trialkylsilyl group at C-3 or C-5, the halogen at the 6-(2-)posit ...