An oxidation system comprising phenyliodine(III) diacetate (PIDA) and iodosobenzene with inorganic bromide, i.e., sodium bromide, in an organic solvent led to the direct introduction of carboxylic acids into benzylic C-H bonds under mild conditions. The unique radical species, generated by the homolytic cleavage of the labile I(III)-Br bond of the in situ-formed bromo-λ 3-iodane, initiated benzylic carboxylation with a high degree of selectivity for the secondary benzylic position.
Dohi, T., Ueda, S., Iwasaki, K., Tsunoda, Y., Morimoto, K., & Kita, Y. (2018). Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system. Beilstein Journal of Organic Chemistry, 14, 1087–1094. https://doi.org/10.3762/bjoc.14.94