Recent Applications of the Zhdankin Reagent in Organic Synthesis

Hypervalent iodine reagents have rapidly become vital synthetic tools in organic chemistry as stoichiometric oxidants and electrophilic sources of various functional groups such as F, CN, and alkynes.[ 1 – 3 ] Many such reagents are now known, with prominent examples such as Dess–Martin periodinane and 2-iodoxybenzoic acid being commercially available. In 1996, the Zhdankin reagent, 1-azido-1,2-benziodoxol-3(1H)-one (3) was first prepared[ 4 ] from 1-hydroxy-1,2-benziodoxol-3(1H)-one (1) and trimethylsilyl azide ( Scheme 1 ). This hypervalent iodine compound can also be efficiently prepared from iodosobenzoic acid (2).[ 5 ] Compound 3 has been shown to primarily act as a source of radical azide.[ 5 , 6 ] Radical reactivity can be initiated thermally or with a peroxide catalyst. The use of this reagent in synthesis has grown considerably since 2013, which may relate to the rise of photoredox catalysis. The latter methodology allows the generation of radicals under particularly mild conditions. The Zhdankin reagent is frequently employed in tandem with a metal catalyst such as copper[ 7 – 12 ] or iron.[ 13 , 14 ] This article highlights some notable applications of molecule 3 that have appeared since 2016.