(-)-.alpha.,.alpha.-Dichlorocamphorsulfonyloxaziridine: a superior reagent for the asymmetric oxidation of sulfides to sulfoxides

Abstract

Supplementary Material Available: Crystal data and data collection, structure determination and refinement, numbering scheme, and tables of crystal data and structure determination, fractional atomic coordinates and isotropic thermal parameters, and interatomic distances and angles for Cu[C(C6H4-CN)4]B-F4-xC6H5N02 (6 pages); listing of observed and calculated structure factors (3 pages). Ordering information is given on any current masthead page.

A Convenient Approach to 16‐, 19‐, and 22‐Membered 2,2′‐Bipyridine Thiacrown Ethers and Their Conformation Preferences

“…This is consistent with the chemical shifts of pyridine protons (δ = 7.85 ppm) in the annulated 6,6Ј-bis-(methylsulfanyl)-2,2Ј-bipyridine [20] 11 (see Figure 2) and the crystal structures of compounds 5a-c (see below). As an extension of these investigations, monosulfoxides 6a-c were obtained after direct asymmetric oxidation in the presence of the chiral oxaziridine developed by Davis et al [22] The highest enantioselectivity was obtained for sulfoxide 6b, which contained a 19-membered ring. The preferred conformation of this macrocycle in the solid state was established by X-ray crystal structure analysis.…”

A facile approach to 2,2′-bipyridine based thiacrown ethers and their sulfoxides by DA-rDA reaction of 5,5′-bi-1,2,4-triazine thiamacrocycles. The conformation studies

“…Finely, we have evaluated the asymmetric sulfoxidation of compounds 5a-c using chiral oxaziridine developed by Davis. 8 The reactions were performed in methylene chloride at room temperature (Scheme 3). Under these conditions the monosulfoxides 7a-c could be obtained in reasonable or good yield.…”

Self-disproportionation of enantiomers (SDE) of chiral sulfur-containing compounds via achiral chromatography

“…This is based on the fact that the reported enantiomeric excess values differ very much for derivatives having very similar structures. Among them there are papers co-authored by one of us [99][100] devoted to the asymmetric oxidation of 2,2'-bipyridine alkyl sulfides 15a-e to non-racemic 2,2'-bipyridine alkyl sulfoxides 16a-e and bis-sulfoxides 17a-e using either (+)- (8,8-dichlorocamphorylsulfonyl) oxaziridine (method A) 101 or the Kagan reagent (method B) 91 (Scheme 9). Scheme 9.…”