Atom-economical group-transfer reactions with hypervalent iodine compounds

Abstract

Hypervalent iodine compounds, in particular aryl-λ3-iodanes, have been used extensively as electrophilic group-transfer reagents. Even though these compounds are superior substrates in terms of reactivity and stability, their utilization is accompanied by stoichiometric amounts of an aryl iodide as waste. This highly nonpolar side product can be tedious to separate from the desired target molecules and significantly reduces the overall atom efficiency of these transformations. In this short review, we want to give a brief summary of recently developed methods, in which this arising former waste is used as an additional reagent in cascade transformations to generate multiple substituted products in one step and with high atom efficiency.

N‐Heterocycle‐Stabilized Iodanes: From Structure to Reactivity

“…In recent years, hypervalent iodine compounds have found widespread applications as versatile and environmental benign reagents for a plethora of oxidative transformations . They are established as easy to handle and bench‐stable electrophilic group transfer reagents for “unusual” electrophiles such as arenes, alkenes, alkynes, azides, or perfluoroalkyl groups . Initially investigated iodane‐based oxidants such as iodoso‐ or iodylbenzene had unfavorable drawbacks.…”

“…[1][2][3] They are established as easy to handlea nd bench-stable electrophilic group transferr eagents for" unusual" electrophiles such as arenes, alkenes,alkynes, azides, or perfluoroalkyl groups. [4][5][6][7][8] Initially investigatedi odane-based oxidants such as iodoso-o ri odylbenzene had unfavorable drawbacks. Extensive secondary intermolecular I···O interactions of unstabilized iodanesp roduced highlyi nsoluble and thermally labile polymeric networks.…”

Photocatalytic Umpolung ofN- andO-substituted alkenes for the synthesis of 1,2-amino alcohols and diols

“…[38][39][40][41][42] Recently, our group has exploited the nucleophilicity of the carboxylate group of EBX reagents in atomeconomical reactions such as the 1,1-oxyalkynylation of diazo compounds and the ring-opening/oxyalkynylation of thiiranes. [43][44][45][46] Therefore, EBX reagents appear ideally suited for the functionalization of radical cations due to their dual nucleophilic/somophilic nature. For what concerns atom economical enamide 1,2-difunctionalization with benziodoxole reagents, the Gillaizeau group has reported an iron-catalyzed enamide oxyazidation (Scheme 1B, a: X ¼ N 3 ) with Zhdankin's reagent.…”

Ethynylbenziodazolones (EBZ) as Electrophilic Alkynylation Reagents for the Highly Enantioselective Copper‐Catalyzed Oxyalkynylation of Diazo Compounds

“…[6e, f, 7] The latter is particularly interesting, as it allowsb oth parts of the reagent (iodobenzoica cid and alkyne) to be transferred to the product. [8] The use of ac opper catalyst with ac hiral bisoxazoline (BOX) ligand gave access to propargylic esters with high enantiopurity. [6f] These new transformations have furthere xtended the scope of multiple-functionalization of metal-carbene intermediates, ar apidly expanding field of organic chemistry.…”