Diverse reactivity of carbenes and silylenes towards fluoropyridines

The reaction of IDipp with C 5 F 5 N led to functionalization of all three carbon atoms of the imidazole ring with HF 2 − as the counter-anion (1). Reactivity with 2,3,5,6-tetrafluoropyridine gives only C-F bond activation leaving C-H bonds intact ( 5b ). The reaction of SIDipp with C 5 F 5 N in the presence of BF 3 afforded the ring cleavage product (3). Analogous reactions with silylene led to oxidative addition at the Si( ii ) center. The activation of the para C-F bond of C 5 F 5 N by IDipp led to functionalization of all three carbon atoms of the imidazole ring. When the para C-F bond is replaced with a C-H bond, IDipp activates the other C-F bonds leaving the C-H bond intact.