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A general strategy for visible-light-enabled site-selective trifluoromethylative pyridylation of unactivated alkenes has been developed using pyridines and triflic anhydride (Tf2 O). Intriguingly, the N-triflylpyridinium salts, generated in situ from pyridines and Tf2 O, serve as effective modular bifunctional reagents to install both CF3 and pyridyl groups to various olefins while controlling C4-selectivity in radical addition to the pyridine core. This synthetic route exhibited broad substrate scope under metal-free and mild photocatalytic conditions, granting efficient access to valuable C4-alkylated pyridines and quinolines without requiring prefunctionalization of the reaction site.
Lee et al. (Tue,) studied this question.