The stereochemistry of thiane oxidation

Chemoselective Synthesis and Anti-Kinetoplastidal Properties of 2,6-Diaryl-4H-tetrahydro-thiopyran-4-one S-Oxides: Their Interplay in a Cascade of Redox Reactions from Diarylideneacetones

“…NMR and LCMS analyses were fine for sulfoxide for both products. Further to previous studies [42][43][44], the NMR spectra of the major isomer agree From a stereochemistry point of view, the oxidation of the cis sulfide should give two different diastereoisomers, depending on the position of the oxygen. In one case, it is in an equatorial position (hereafter quoted as anti-cis sulfoxide isomer), whereas in the other case, it is in an axial position (hereafter quoted as syn-cis sulfoxide isomer) (Figure 1).…”

“…In one case, it is in an equatorial position (hereafter quoted as anti-cis sulfoxide isomer), whereas in the other case, it is in an axial position (hereafter quoted as syn-cis sulfoxide isomer) (Figure 1). The most stable configuration of the sulfoxide for this kind of heterocycle has been discussed in several studies [42,50,51]. According to these works, the axial position is surprisingly more stable than the equatorial one; the syn-cis is therefore expected to be the major isomer, if not the unique one.…”

“…To our knowledge, the synthesis of 2,6-DA-4-THTP sulfoxides derivatives has been described in only three articles, which were limited to the oxidation of the cis isomer [42][43][44]. In each case, wet bromine was used to oxidize the sulfur, with a variable yield of up to 83%.…”

Efficient and Stereoselective Syntheses of Isomerically Pure 4-Aminotetrahydro-2H-thiopyran 1-Oxide Derivatives

“…Also, NMR spectra for β-axial protons (Hc) of trans- 3a – d and cis- 4a – d appear at lower field than β-equatorial ones (Hd), which suggests that the sulfoxide groups of trans- 3 and cis- 4 adopt an axial configuration. ,− Furthermore, NOESY experiments revealed significant correlations between Hc and He and between Hc and Hf in cis -Ns- 4a , suggesting that the sulfonamide groups of trans -Ns- 3a and cis -Ns- 4a occupy axial and equatorial positions, respectively.…”

“…The stereochemical outcome of the oxidation of tetrahydro-2 H -thiopyran derivatives substituted at the C(4) position by different oxidizing reagents and substituents has been well-described. − Johnson reported the formation of predominantly axial sulfoxides of tetrahydro-2 H -thiopyran 1-oxide bearing hydrocarbon substituents as well as an almost pure equatorial sulfoxide. Klein demonstrated the stereoselective preparation of isomerically pure 4-hydroxytrahydro-2 H -thiopyran 1-oxides. However, the stereoselective synthesis of isomerically pure 4-aminotetrahydro-2 H -thiopyran 1-oxide derivatives has not been reported.…”