Recent Progress in Synthetic Applications of Hypervalent Iodine(III) Reagents

Hypervalent iodine(III) compounds have found wide application in modern organic chemistry as environmentally friendly reagents and catalysts. Hypervalent iodine reagents are commonly used in synthetically important halogenations, oxidations, aminations, heterocyclizations, and various oxidative functionalizations of organic substrates. Iodonium salts are important arylating reagents, while iodonium ylides and imides are excellent carbene and nitrene precursors. Various derivatives of benziodoxoles, such as azidobenziodoxoles, trifluoromethylbenziodoxoles, alkynylbenziodoxoles, and alkenylbenziodoxoles have found wide application as group transfer reagents in the presence of transition metal catalysts, under metal-free conditions, or using photocatalysts under photoirradiation conditions. Development of hypervalent iodine catalytic systems and discovery of highly enantioselective reactions using chiral hypervalent iodine compounds represent a particularly important recent achievement in the field of hypervalent iodine chemistry. Chemical transformations promoted by hypervalent iodine in many cases are unique and cannot be performed by using any other common, non-iodine-based reagent. This review covers literature published mainly in the last 7-8 years, between 2016 and 2024.

(Indol-3-yl)(DMIX)Iodonium Salts: Novel Electrophilic Indole Reagents

A new umpolung approach to the C3-H functionalization of indoles with diverse nucleophiles based on the intermediate formation of I(III) reagents is described. The 3,5-dimethylisoxazol-4-yl auxiliary allows for selective indole transfer under catalyst-free conditions, which was impossible using previously reported reagents. Combining the mildness of transition-metal-free conditions and the high reactivity of hypervalent iodine reagents, this protocol tolerates various functional groups and provides access to indoles that are difficult to prepare conventionally.

Intramolecular cyclization of m-homoprenylphenols through oxidative nucleophilic aromatic substitution

We developed an intramolecular cyclization of m-homoprenylphenols and related m-prenylphenols to bicyclic skeletons by hypervalent iodine reagents through an oxidative nucleophilic aromatic substitution using the prenyl group as a carbon nucleophile. The reaction was applicable for the syntheses of 5/6-, 6/6-, and 7/6-fused ring systems.