Development of New Radical‐Mediated Selective Reactions Promoted by Hypervalent Iodine(III) Reagents

Abstract

In this account, we describe our recent developments on the four‐types of hypervalent iodine(III)‐mediated radical reactions in organic synthesis. Firstly, the activation of aldehydic C−H bonds can be successfully effected with hypervalent iodine(III) reagents, thereby allowing the synthesis of various ketones with high efficiency. Secondly, the site‐selective oxidation of unactivated C(sp3)−H bonds of hydrocarbon substrates was realized with designer hypervalent iodine(III) reagents. Thirdly, various perfluoroalkyl and α‐aminoalkyl radicals can be generated from sodium perfluoroalkanesulfinates and sodium α‐aminoalkanesulfinates, respectively, under the influence of hypervalent iodine(III) reagents. Finally, the efficient generation of difluoromethyl radical from hypervalent difluoroacetoxyliodine(III) reagent was realized by photolysis. These four different strategies are illustrated by using various selective radical approaches.

Updates on hypervalent-iodine reagents: metal-free functionalisation of alkenes, alkynes and heterocycles

“…1,2 Since the early 1990s, the chemistry of hypervalent-iodine (HVI) compounds has been flourishing because of its enormous synthetic applications. The role of HVI compounds as reagents or as catalysts in α-functionalisation of carbonyl compounds, [3][4][5] cyclisations, 6,7 oxidative rearrangements, [8][9][10] alkene difunctionalisation, 11,12 atom and functional-group transfer reagent, [13][14][15][16] oxidation, 17 etc., is covered in several reviews and book chapters. [18][19][20][21][22][23][24][25][26] The intense interest is mainly due to the remarkable oxidising properties of HVI reagents and their attractive features, viz., easy to handle, low toxicity, easy availability, and environmental benignity.…”

PhI(OAc)2-mediated aminoacyloxylation of β,γ-unsaturated hydrazones using Togni reagent II as an acyloxyl precursor

“…Based on our previous mechanistic studies and related literature, 11 we proposed a plausible mechanism for the present aminoacyloxylation reaction using 1a as an example (Scheme 5). First, zwitterion A was obtained by 1a and Togni reagent II, and radical intermediate B was formed by a single-electron-transfer (SET) process in the presence of PIDA, together with the release of − OAc and I-centered radical species.…”

Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field

“…One of the emerging areas in the chemistry of iodine(III) reagents with high synthetic potential is the visible-light in-duced I-O bond homolysis [152], which is currently employed mainly for the initiation of chain processes or stoichiometric oxidations, but definitely should find application in catalysis.…”