Selective carboxylation of reactive benzylic C-H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

Toshifumi Dohi; Shohei Ueda; Kosuke Iwasaki; Yusuke Tsunoda; Koji Morimoto; Yasuyuki Kita

doi:10.3762/bjoc.14.94

Selective carboxylation of reactive benzylic C-H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

Beilstein J Org Chem. 2018 May 16:14:1087-1094. doi: 10.3762/bjoc.14.94. eCollection 2018.

Authors

Toshifumi Dohi¹, Shohei Ueda¹, Kosuke Iwasaki¹, Yusuke Tsunoda¹, Koji Morimoto¹, Yasuyuki Kita²

Affiliations

¹ College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan. Tel: +81-77-561-4908.
² Research Organization of Science and Technology, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga 525-8577, Japan. Tel.

Abstract

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-λ³-iodane, initiated benzylic carboxylation with a high degree of selectivity for the secondary benzylic position.

Keywords: C–H activation; carboxylic acids; iodine; oxygenation; radicals.