Described herein is a direct approach to symmetrical thioethers from either aromatic carboxylic acids or aromatic aldehydes with elemental sulfur (S-8) by using a reducing system combined with InI3 and 1,1,3,3-tetramethyldisiloxane (TMDS). This sulfidation does not require functionalized sulfur reagents, such as sulfides, disulfides, or metal sulfides, and it simultaneously forms two carbon-sulfur bonds in a single catalytic system.
The direct incorporation of task-specific substituents exclusively at the meso positions of neutral sulfur-bridged 5,16-dihydro22]annulene(188.8.131.52) is described. This method allows for the incorporation of long hydrocarbon chains, which are otherwise not easily accessible through a conventional aldehyde condensation approach.
Both the efficiency and the stereoselectivity in baker's-yeastmediated reduction of ketones are strongly influenced by both the presence and the position of sulfur substituents, or indeed by the use of sulfur-containing additives. Interestingly the oxidation level of the sulfur substituent has a powerful impact on the outcome of the yeast reduction. It is apparent that use of the sulfone moiety as a substituent to influence the efficiency and stereoselectivity in ketone reduction is substantially more effective than use of the analogous sulfide and sulfoxide moieties.
In this study, we have employed dithiooxamide, a solid, odorless, and commercially available compound, as a sulfur surrogate for the preparation of dialkyl sulfides from available alkyl halides in high yields. This sulfur transfer agent was also used for a copper-catalyzed high-yielding preparation of diaryl sulfides from their available aryl halides and for the preparation of thia-Michael adducts in high yields. All the reactions were performed under odorless conditions in wet PEG200 (PEG = polyethylene glycol), which is an ecofriendly, safe, and recoverable solvent. The protocols were easily applicable to large-scale operation.
A range of aryl sulfinates can be oxidatively dimerized to generate substituted biphenyls with concomitant extrusion of sulfur dioxide with a palladium catalyst. Catalytic amounts of TEMPO and excess oxygen are utilized as oxidants to regenerate the palladium catalyst.
Three-component reactions involving amines, aldehydes, and elemental sulfur powder are reported to afford thioamides in a simple one-pot procedure in the absence of a catalyst. A variety of thioamides can be obtained in good to excellent yields up to 88%.
Copper-catalyzed formation of sulfur-nitrogen bonds can be performed by a dehydrocoupling of aryl thiols with amines. Sulfenamides or sulfonamides can be produced by the use of a copper catalyst in air or under oxygen atmosphere. Furthermore, a reaction involving the combination of a palladium catalyst and a copper catalyst selectively afforded sulfinamides.
A new method has been developed for the copper-mediated trifluoromethylthiolation of allylic halides by using potassium fluoride, elemental sulfur, and (trifluoromethyl)trimethylsilane in anhydrous N,N-dimethylformamide. This protocol provides facile access to a variety of allylic trifluoromethyl thioethers in moderate to good yields under mild, ligand-free reaction conditions.
Naphthyridines have been identified as structural elements in sulfurized polyacrylonitrile, which is a common electrode material in lithium-sulfur batteries. Some dibenzonaphthyridine derivatives with a fused dithiolo moiety were prepared as model compounds for battery studies. These heterocyclic systems were prepared via the corresponding diphenyldicarbamide intermediate. Followed by naphthyridione formation, stepwise installation of the dithiolane subunit occurred in a straightforward manner. In the solid state, the heteroaromatic system is completely planar and was thoroughly characterized. Initial battery cycling tests indicated a potential use of such structural motifs in sulfur-lithium systems.
The use of liquid sulfur dioxide as a reaction solvent facilitates the Ritter reaction between alcohols and nitriles. In(OTf)(3) was found to be a viable catalyst for this transformation. The newly developed catalytic conditions for the Ritter reaction were successfully applied to the synthesis of various amides, which were formed in good to excellent yields. The catalytic activation of secondary alcohols for Ritter reactions in liquid sulfur dioxide was also found to be effective.