Chiral Ligands in Hypervalent Iodine Compounds: Synthesis and Structures of Binaphthyl‐Based λ³‐Iodanes

Abstract

Several novel binaphthyl‐based chiral hypervalent iodine(III) reagents have been prepared and structurally analysed. Various asymmetric oxidative reactions were applied to evaluate the reactivities and stereoselectivities of those reagents. Moderate to excellent yields were observed; however, very low stereoselectivities were obtained. NMR experiments indicated that these reagents are very easily hydrolysed in either chloroform or DMSO solvents leading to the limited stereoselectivities. It is concluded that the use of chiral ligands is an unsuccessful way to prepare efficient stereoselective iodine(III) reagents.

Recent Progress in Cyclic Aryliodonium Chemistry: Syntheses and Applications

“…Among them, binaphthyl-based chiral iodoniums 36 have interesting properties as a result of the naphthyl moieties restricting the axial rotation (Scheme A). − Several approaches to binaphthyl-based chiral acyclic aryliodoniums are disclosed in the past years. Recently, Wirth et al have prepared novel binaphthyl-based chiral acyclic iodonium reagents 40 from λ 3 -iodanes and BINOL ( R )-analogues 38 , as depicted in Scheme B. The cyclic aryliodoniums are less developed in the past years.…”

“…Chiral hypervalent iodine chemistry has been steadily increasing interest in recent years, especially the acyclic aryliodoniums as potential chiral reagents in asymmetric synthesis over the last decades . Among them, binaphthyl-based chiral iodoniums 36 have interesting properties as a result of the naphthyl moieties restricting the axial rotation (Scheme A). − Several approaches to binaphthyl-based chiral acyclic aryliodoniums are disclosed in the past years. Recently, Wirth et al have prepared novel binaphthyl-based chiral acyclic iodonium reagents 40 from λ 3 -iodanes and BINOL ( R )-analogues 38 , as depicted in Scheme B.…”

“…123 Among them, binaphthyl-based chiral iodoniums 36 have interesting properties as a result of the naphthyl moieties restricting the axial rotation (Scheme 13A). 125 as depicted in Scheme 13B. The cyclic aryliodoniums are less developed in the past years.…”

Oxidation of BINOLs by Hypervalent Iodine Reagents: Facile Synthesis of Xanthenes and Lactones

“…Hypervalent iodine reagents are mild oxidants and enable different functionalizations in an achiral or chiral manner [21] . We are interested in designing and synthesizing chiral hypervalent iodine compounds and using them in asymmetric oxidation transformations [22] . In a recent research, BINOL was used as chiral ligand to react with iodosylbenzene, expecting to obtain a binaphthyl‐based chiral hypervalent iodine compound.…”

“…[21] We are interested in designing and synthesizing chiral hypervalent iodine compounds and using them in asymmetric oxidation transformations. [22] In a recent research, BINOL was used as chiral ligand to react with iodosylbenzene, expecting to obtain a binaphthyl-based chiral hypervalent iodine compound. However, the expected product was not formed, but products 3 a and a nine-membered ketone lactone 4, which had been reported earlier (Scheme 1b), [23] were observed instead.…”