Synthesis of Chiral Diaryliodonium Salts, 1,1‘-Binaphthyl-2-yl(phenyl)iodonium Tetrafluoroborates:  Asymmetric α-Phenylation of β-Keto Ester Enolates

Conformationally-Flexible Chiral Hypervalent Organoiodine Catalysts for Enantioselective Oxidative Transformations

“…5 The asymmetric oxidation of sul des gave sulfoxides with moderate enantioselectivities on use of oligomeric chiral iodine(III) species 1, the structure as later proposed by Koser, 6 generated from iodosobenzene (PhIO) and tartaric anhydride derivatives. After this paper was published, several chiral hypervalent iodine reagents were developed by the groups of Koser (for oxidation of sul des), 7 Wirth (for dioxytosylation of styrene), 8 Kita (for oxidation of sul des), 9 Ochiai (for oxidative α phenylation of β ketoesters), 10 Zhdankin (for oxidative desymmetrization of vicinal diols), 11 Fujita (for oxidative cyclization of acyloxyalkenes), 12 and Birman (for oxidative dearomatization of phenols). 13 But the enantioselectivities obtained in these reactions were still moderate.…”

Design and asymmetric synthesis of chiral diaryliodonium salts

“…These peaks were identified by the 2:1 ratio observed in compound 22. Figure 3 depicts a selection of the non-identical peaks seen in 13 C-NMR, where the ortho-and parasubstituents are clearly differentiated. For remaining parts of the combined spectra, se the Supplementary Information.…”

“…1 H and 13 C-NMRs of all reported compounds are available in the online version, at doi:10.1016/j.tet.2010.xxxxx.…”

“…12 In 1999, Ochiai and coworkers reported the synthesis of 1,1'-binaphthyl-2-yl(phenyl)iodonium salts 1 (Scheme 1). 13 The efficiency of the salts was evaluated in arylations of β-keto esters, and gave α-phenylated products in moderate yields and enantioselectivities. 13 In a similar fashion, Zhdankin et al prepared chiral benziodazole structures, where the Nfunctionalized amide moiety acted as internal anion.…”

“…13 The efficiency of the salts was evaluated in arylations of β-keto esters, and gave α-phenylated products in moderate yields and enantioselectivities. 13 In a similar fashion, Zhdankin et al prepared chiral benziodazole structures, where the Nfunctionalized amide moiety acted as internal anion. 14 Aggarwal and Olofsson used a different strategy to realize enantioselective α-arylation of carbonyl compounds with diaryliodonium salts.…”