Cyclic Hypervalent Iodine Reagents for Azidation: Safer Reagents and Photoredox Catalyzed Ring Expansion

Azides are building blocks of increasing importance in synthetic chemistry, chemical biology and materials science. Azidobenziodoxolone (ABX, Zhdankin reagent) is a valuable azide source, but its safety profile has not been thoroughly established. Herein, we report a safety study of ABX, which shows its highly hazardous nature. We further introduce and study two derivatives, <i>t</i>Bu-ABX and ABZ (azidobenziodazolone). ABZ displayed a similar reactivity but a better safety profile than ABX, and could be used in established photoredox- and metal-mediated azidation processes, as well as in a new ring-expansion of silylated cyclobutanols to give azidated cyclopentanones.