Umpolung Of Electron-Rich Heteroarenes With Hypervalent Iodine Reagents

Five-membered heterocycles are well known for their innate nucleophilicity. In contrast, reaction of these heterocycles as electrophiles is less established and has become only recently an intensively investigated research area in synthetic chemistry. The use of hypervalent iodine reagents for the umpolung of the nucleophilic reactivity has been especially successful. This review provides a comprehensive overview regarding the generation of electrophilic intermediates from electron-rich heterocycles using hypervalent iodine reagents. The functionalization with different heteroatoms, arenes or heteroarenes nucleophiles is then described.