Cyclic Sulfides

Proton-Decoupled Carbon-13 NMR Spectroscopy in a Lyotropic Chiral Nematic Solvent as an Analytical Tool for the Measurement of the Enantiomeric Excess

“…Among other potential applications of this method, the possibility to discriminate chiral molecules possessing an asymmetric heteroatom, such as sulfur or phosphorus nuclei is a very interesting challenge. Therefore, we have attempted to distinguish between the enantiomers of chiral sulfur derivatives. , It is known that many of them are difficult to discriminate with classical analytical NMR methods involving chiral shift reagents for example. For this purpose, a sulfoxide, a sulfoximine, and a sulfilimine derivative were investigated using carbon-13 NMR, and the results are reported in Table .…”

Diastereoselective Episulfidation of Strained Cyclic Alkenes by a Thiophene Endoperoxide versus Epoxidation by Dimethyldioxirane

“…The episulfidation of trans -cyclooctene ( trans -5b ) led exclusively to the trans -thiirane 6b . Unfortunately, no experimental and/or theoretical strain energies of fused-ring thiiranes are available;10c therefore, we assume that the isomer cis - 6b is thermodynamically more stable than the trans - 6b one. This assumption is based on the data reported for the corresponding olefins and epoxides (the difference in the strain energy for the cyclooctenes trans / cis - 5b is 9.8 kcal/mol; for the corresponding epoxides trans / cis - 8b it is 4.2 kcal/mol) .…”

“…The epoxidation of alkenes is beyond doubt one of the most important and best investigated synthetic transformations. A variety of reagents are known, which may be used to transfer an oxygen atom directly to an alkene. − Several enantioselective epoxidations demonstrate the significance of this well-explored methodology in organic chemistry. − In contrast, the direct episulfidation of alkenes is reported only for a few special examples and has yet not been synthetically applied. , To transform alkenes to their episulfides, usually indirect methods are used, of which the preparatively more useful ones are the conversion of epoxides to their episulfides by thiocarbonyl-containing reagents (e.g., thiourea) or the addition of a sulfenyl chloride to an alkene and subsequent base-catalyzed ring closure …”

Direct Episulfidation of Alkenes and Allenes with Elemental Sulfur and Thiiranes as Sulfur Sources, Catalyzed by Molybdenum Oxo Complexes

“…The traditional method to prepare thiiranes is from the corresponding epoxides, by attack with an appropriate sulfur nucleophile and subsequent cyclization, a sequence that is still commonly employed, giving effective access to the episulfides of unstrained acyclic and cyclic alkenes, for example, styrene and cyclohexene . In contrast, the conversion of an alkene to a thiirane by direct sulfur-atom transfer is as yet a scarce transformation and remains a synthetic challenge of timely interest. Like the epoxidation, which for synthetic purposes is one of the best investigated oxidations in organic chemistry, a stereoselective one-step episulfidation of alkenes to thiiranes without oligomerization and polymerization would constitute an attractive but demanding aim.…”