Sulfur-Based Chiral Iodoarenes: An Underexplored Class of Chiral Hypervalent Iodine Reagents

Abstract

Chiral hypervalent iodine reagents are active players in modern stereoselective organic synthesis. Structurally diverse chiral hypervalent iodine reagents have been synthesised and extensively studied, but hypervalent iodine reagents containing chiral sulfur stereogenic centre are scarce and their synthesis is challenging. A small library of iodoarenes containing chiral sulfinamide and chiral sulfoximine moieties has been synthesised using commercially available reagents. The oxidation of the chiral iodoarene precursors to iodine(III) reagents was cumbersome due to facile overoxidation of the sulfoxide moiety and hence loss of chirality under various oxidation conditions. Oxidation of chiral sulfonimidoyl derivatives to the corresponding hypervalent iodine reagents was successful and led to novel sulfur-based chiral iodine(III) reagents.

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

“…[27][28][29][30][31][32][33][34][35][36][37] The chemistry of specific classes of HVI compounds has been summarised from time to time in various specialised reviews and accounts. [38][39][40][41][42][43][44][45] Thus, the present article will not be inclusive but will emphasise only the key aspects and most relevant components for this review. This article aims to give a brief synopsis of the HVI chemistry, focusing mainly on the metalfree syntheses that have taken place in the past couple of years.…”

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

“…Very recently, Wirth's group has successfully synthesized a chiral acetoxy substituted benziodazole with a sulfoximine skeleton and confirmed its structure by X-ray crystallography. [170] Examples of recently reported reactions using acetoxybenziodoxoles as reagents are presented below.…”

Catalytic stereoselective synthesis involving hypervalent iodine-based chiral auxiliaries

“…45 Later, a number of protocols have been developed using different chiral iodoarenes; however, most of these protocols yielded modest enantioselectivities (<58% ee) despite the numerous efforts put in this area of research. [46][47][48][49][50][51] Therefore, there is huge potential in designing new methods for the α-oxytosylation of ketones to reach to the synthetically relevant enantioselectivities.…”

“…40,41 Another interesting aspect of these reagents is to use them as chiral auxallaries to achieve various stereoselective reactions. [42][43][44][45][46] In recent years, several hypervalent iodine chemists have moved their attention in finding new chiral iodoarene precatalysts and studying their application in developing stereoselective reactions with high enantiomeric excess. The key aspect of these enantioselective reactions is the in situ generation of hypervalent iodine(III) catalytic species through the oxidation of iodoarene precatalysts using stoichiometric oxidants such as mCPBA, selectfluor, and Oxone®.…”