Enantioselective Iodine(I/III) Catalysis in Organic Synthesis

Abstract

Chiral aryliodine(III)r eagents have provided an advancedc oncept for enantioselective synthesis and catalysis.W ith the advent of chiral iodine(I/III) catalysis,m anyd ifferent structures have been explored in the area. Thec urrently most prominent catalyst design is based on ar esorcinol core and the attachment of two lactic side chainsb earing ester or amide groups.T his enables ap rivileged modular catalyst synthesis,i nw hich fine-tuning with respect to the specificr eaction requirement is straightforward. Thep resent overview summarizes the structural variation and optimization of such chiral aryliodine catalysts andd iscusses structural properties of the active iodine(III) catalyst states.T he status quo of enantioselective iodine(I/III) oxidation catalysis with respect to intramolecular and intermolecular reaction control is reviewed, and specific aspects of the individual catalytic cycles are discussed. 1I ntroduction 2C hiral Aryliodine Catalysts 3E nantioselective Catalysis 3.1 Catalytic DearomatizationReactions 3.2 Formal C(sp 3 )Functionalization 3.3 Difunctionalization of Alkenes 4C onclusionScheme 14. Aryliodine-catalyzede nantioselective intermolecular para-dearomatization of phenols and aniline.Scheme15. Aryliodine-catalyzed enantioselective intermolecular para-dearomatization by Maruoka.Scheme30. Catalytic enantioselective version of the aminofluorination reaction.Scheme 28. Enantioselectiveo xidative cyclization of w-alkenylcarboxylic acids.Scheme29. Catalytic intramolecular diaminationo fa lkenes.

2-Iodoxybenzoic acid ditriflate: the most powerful hypervalent iodine(v) oxidant

“…In recent years, the interest in synthetic applications of hypervalent iodine compounds as versatile oxidizing reagents and catalysts has experienced an explosive growth. [1][2][3][4][5][6][7][8][9] Hypervalent iodine(V) reagents represent a particularly important class of oxidants extensively employed in organic synthesis. 2-Iodoxybenzoic acid (IBX, structure 1 in Fig 1) and the product of its acetylation Dess-Martin periodinane (DMP, 2) have become the most common oxidizing reagents used for selective oxidation of alcohols to carbonyl compounds and other synthetically useful oxidative transformations.…”

Supramolecular Halogen Bonds in Asymmetric Catalysis

“…Chiral hypervalent organoiodine reagents have been used in different oxidative transformations in which the reagent is temporally inserted into a suitable substrate and is afterwards displaced by a nucleophilic species (Figure 2B; for recent reviews, see: Claraz and Masson, 2018;Flores et al, 2019;Parra, 2019). Typically, these reagents are generated in situ from chiral iodoarenes by sacrificial oxidants, which are also used to regenerate the hypervalent organoiodine.…”

Evolution of N‐Heterocycle‐Substituted Iodoarenes (NHIAs) to Efficient Organocatalysts in Iodine(I/III)‐Mediated Oxidative Transformations

“…When embedded into a chiral scaffold, they are also crucial to induce chirality in enantioselective oxidative couplings. [21][22][23] In 2012, Legault and co-workers observed that catalysts which exhibit a strong dative bond between the Lewis basic moiety and the hypervalent iodine center were inefficient in the α-tosyloxylation of carbonyl compounds. [24] However, their reactivity could be greatly enhanced by the introduction of steric demand ortho to the iodine center, as proved for amide 1 (Figure 1-a).…”