Sulfide Units Research Articles

Total Synthesis of Dragmacidins G and H.

The total synthesis of dragmacidins G and H was achieved for the first time by employing nucleophilic aromatic substitution and site-selective cross-coupling reactions using appropriately functionalized pyrazines as substrates. The evaluation of antibacterial activities of dragmacidin G, dragmacidin H, and synthetic analogues against Staphylococcus aureus and the efflux pump-deficient Salmonella Typhimurium revealed that the presence of a Br group on the indole ring adjacent to the sulfide unit was important for increasing antibacterial activities.

Preparing glycosyl benzothiazoles from 2-isocyanoaryl thioethers and glycosyl radicals under thermal conditions.

Herein, we report a method for preparing glycosyl benzothiazoles via radical cascade cyclization, in which glycosyl radicals are generated from readily available and bench-stable allyl glycosyl sulfones. This cascade reaction proceeds under simple conditions and tolerates a broad substrate scope in high yield with excellent stereoselectivity. Mechanistic studies support that the reactions proceed via the intermediacy of imidoyl radicals, which attack the appended sulfide unit by a SH2 process to forge the thiazole ring.

Core Cross‐Linking Enhances the Anti‐Inflammatory Performance of Oxidation‐Sensitive Polymeric Micelles

AbstractNanomaterials able to scavenge biologically relevant oxidants (reactive oxygen species, ROS) can directly act as anti‐inflammatory agents. Here, micelles made of amphiphilic poly(ethylene glycol)(PEG)‐polysulfide block copolymers are focused on; the polysulfide blocks are responsible of ROS‐scavenging and are composed of propylene sulfide and ethylene sulfide units in ratios of 20:0, 15:5, 10:10. These polymers can be intramicellarly cross‐linked through thermal thiol‐yne reaction of terminal alkynes (trithiol cross‐linker). Self‐assembled and cross‐linked micelles are virtually identical in size and scavenging kinetics, but greatly differ in stability against dilution (critical aggregation concentration (CAC) respectively of ≈0.1 and <0.01 mg mL−1) and in the final state after oxidation (soluble polymers vs cross‐linked nanoparticles). Most importantly, self‐assembled micelles have significant toxicity and damage cell membranes already at 0.5 mg mL−1, which seriously hampers their anti‐inflammatory activity. On the contrary, cross‐linked micelles do not appreciably harm cells at least up to 1 mg mL−1, and effectively inhibit the production of inflammatory cytokines in activated macrophages. In this study, a detailed interpretation of the morphological evolution of the two types of micelles during oxidation is provided and it is proved that core cross‐linking significantly widens the therapeutic window.

Hydrogen atom abstraction by a high-spin [FeIII=S] complex

Iron sulfur clusters are critical to a plethora of biological processes; however, little is known about the elementary unit of these clusters, namely the [Fe=S]n+ fragment. Here, we report the synthesis and characterization of a terminal iron sulfido complex. Despite its high spin (S = 5/2) ground state, structural, spectroscopic, and computational characterization provide evidence for iron sulfur multiple bond character. Intriguingly, the complex reacts with additional sulfur to afford an S = 3/2 iron(III) disulfido (S2 2-) complex. Preliminary studies reveal that the sulfido complex reacts with dihydroanthracene to afford an iron(II) hydrosulfido complex, akin to the reactivity of iron oxo complexes. By contrast, there is no reaction with the disulfido complex. These results provide important insight into the nature of the iron sulfide unit.

Impact of the Heteroatoms on Mobility–Stretchability Properties of n-Type Semiconducting Polymers with Conjugation Break Spacers

The development of stretchable semiconducting polymers through statistical terpolymerization with conjugation break spacers (CBSs) has gained much attention. In this study, we systematically investigated the effects of incorporating CBSs with thioether units into naphthalenediimide (NDI)-based n-type semiconducting polymers on their semiconductivity and stretchability compared to polymers with the corresponding alkyl- and ether-based CBSs. Indeed, six NDI-based semiconducting polymers with CBSs composed of di(ethylene sulfide), tetra(ethylene sulfide), di(ethylene oxide), tetra(ethylene oxide), octylene, and tetradecylene units were synthesized by statistical terpolymerization based on Migita–Kosugi–Stille cross-coupling reactions of 5,5′-bis(trimethylstannyl)-2,2′-bithiophene (2T), 4,9-dibromo-2,7-bis(2-decyltetradecyl)benzo[lmn][3,8]phenanthroline-1,3,6,8-tetraone (Br-NDI-Br), and CBSs. The experimental results indicate that heteroatom-based CBSs would sufficiently affect solid-state packing, intrinsic stretchability, and mobility retentions of the corresponding polymers. Although all of the polymers demonstrated strong edge-on orientations, those with ether-based CBSs displayed the lowest crystallinity among them. This result was attributed to the phase separation induced by highly polar ethylene oxide moieties, leading to inferior charge transport performances and low crack onset strain. In contrast, the thin film of the polymer with thioether-based CBSs showed delayed crack onset strain and a high dichroic ratio. The narrower bond angle of C–S–C (98.9°) than C–O–C (113.3°) calculated by the DFT method led to a more bent conformation along the polymer backbone, which provided a strain-releasing capability to realign the polymer chains. Consequently, the polymers with thioether-based CBSs displayed higher mobility–stretchability properties than those comprising ether-based CBSs. This is the first report on the design, synthesis, and application to organic field-effect transistors (OFETs) of stretchable n-type semiconducting polymer materials, clarifying the impact of heteroatoms on the mobility–stretchability properties of n-type semiconducting polymers with new CBSs having ethylene oxide and ethylene sulfide units.

Synthesis and characterization of sulfide/sulfone-containing 18-8-18-membered-ring ladder-type siloxanes.

Innovative macrocyclic 14-membered molecule (5) and tricyclic 18-8-18-membered-ring ladder-type siloxane-based compound (7), with sulfide units inserted in the backbone were prepared through B(C6F5)3-catalyzed Piers-Rubinsztajn reaction. Further oxidation of 5 and 7 with m-CPBA enables the synthesis of the novel sulfonyl-containing cyclic and ladder-type compound (8 and 9) in high yields. Both tricyclic ladder-type products (7 and 9) show superior thermostability and their well-defined syn-type structures were determined by X-ray crystallographic analysis. The compounds 7 and 9 may become promising building blocks for various new materials.

Halogenated polyethersulfone sulfides

This paper presents the results of a study of random copolyethersulfone sulfides based on 4,4-dichlorodiphenylsulfone, 1,1-dichloro-2,2-di(4-hydroxyphenyl)ethylene, and sodium sulfide. The synthesis of copolyethersulfone sulfides with different ratios of polyethersulfone and polyphenylenesulfone sulfide units was carried out by high-temperature polycondensation by the reaction of nucleophilic substitution in N,N-dimethylacetamide medium and using potassium carbonate as an alkaline agent. The effect of the solvent used on the yield and reduced viscosity of polyethersulfone sulfides was studied. It has been shown that polymers with high reduced viscosity can be obtained in N,N-dimethylacetamide and N,N-dimethylformamide. The growth dynamics of the reduced viscosity of polyethersulfone sulfides was also studied depending on the ratio of sulfone and sulfide groups. The solubility of these polymers in various solvents has been studied.

Free‐Blockage Mesoporous Silica Nanoparticles Loaded with Cerium Oxide as ROS‐Responsive and ROS‐Scavenging Nanomedicine (Adv. Funct. Mater. 46/2022)

Mesoporous Materials In article number 2208316, Xiaohui Ju and co-workers report the design of free-blockage reactive oxygen species (ROS)-responsive mesoporous silica nanoparticles (MSNs) as potential drug delivery systems. Methyl sulfide units are functionalized onto MSNs through co-condensation or grafting pathways. In an ROS-rich environment, the nanocarriers undergo structure and polarity changes and release cargo of cerium oxide nanoparticles to scavenge excessive ROS related to pathological conditions.

NaPON Doping of Na4P2S7 Glass and Its Effects on the Structure and Properties of Mixed Oxy-Sulfide-Nitride Phosphate Glass.

The preparation, properties, and short-range order (SRO) structures of glasses in the series (1-x)[2/3Na2S + 1/3P2S5] + x[1/3Na2S + 2/3NaPO2.31N0.46] = Na4P2S7-6xO4.62xN0.92x, where 0 ≤ x ≤ 0.5 (NaPSON), are reported on. In this study, these mixed oxy-sulfide-nitride (MOSN) glasses were prepared by adding the nitrided material NaPO3-(3/2)yNy; y = 0.46 = NaPO2.31N0.46 (NaPON) to the base sulfide glass Na4P2S7. For comparison purposes, additions of the unitrided material, y = 0, NaPO3, were also studied (NaPSO). Accordingly, large batches of bubble-free glass could be prepared making this route of nitrogen doping amendable toward scaling-up the glass melting process; though, only small amounts of nitrogen could be incorporated in this manner. Nitrogen and sulfur compositional analysis were combined with XPS, Raman, FT-IR, and 31P MAS NMR spectroscopies to determine the amount of retained nitrogen in the glass after melting and quenching and to determine the effect of the added nitrogen and oxygen on the structure of the base pure sulfide glass Na4P2S7, x = 0.0. The nitrogen content increased linearly with the addition of NaPON, but was found, through quantitative 31P MAS NMR analysis, to be approximately half that expected at each value of x. Despite the small amount of nitrogen retained in these glasses, profound increases in the glass transition (Tg) and crystallization temperatures (Tc) were found with increasing x. For the intermediate values of x, 0.2 and 0.3, no crystallization of the supercooled melt was observed even 250 °C above the Tg. It was found that the addition of NaPON to the series caused a disproportionation reaction, where the oxide and oxy-nitride SRO species preferentially formed covalent, networking phosphate chains, forcing the sodium modifier to ionic sulfide units with large fractions of nonbridging sulfurs (NBSs). This disproportionation reaction was also observed in the NaPO3 doped series of glasses, but to a smaller extent. Oxygen was found in both bridging oxygen (BO) and nonbridging oxygen (NBOs) structures while the sulfur was predominantly found in nonbridging sulfur (NBS) structures. N 1s XPS and 31P NMR studies provided insight into the nitrogen bearing phosphorus units and the wt % of nitrogen that was retained in the quenched glasses. It was found that trigonally coordinated nitrogen (Nt) was preferentially retained in the melt, whereas it is proposed that the linearly coordinated (doubly bonded) nitrogen (Nd) accounts for the lost nitrogen in the glasses.

A surface configuration strategy to hierarchical Fe-Co-S/Cu2O/Cu electrodes for oxygen evolution in water/seawater splitting

Fabrication of low-cost but effective catalytic electrode for oxygen evolution is an important issue for water splitting. In this study, a self-supporting electrode composed of hierarchical microstructure was fabricated by a surface configuration strategy. Thin nanosheet-like Fe-Co sulfide units were loaded on one-dimensional Cu2O/Cu framework through an electrodeposition route, during which Cu(OH)2 nanowires were used as a template to generate one-dimensional Cu2O/Cu framework. Benefiting from the unique hierarchal microstructure that can expose more catalytic active centers and facilitate the release of oxygen bubbles, this self-supported Fe-Co-S/Cu2O/Cu catalytic electrode presents superb catalytic activity towards oxygen evolution. In 1 M KOH, the obtained catalytic electrode only requires an overpotential of 338 mV for 50 mA cm−2. It is proposed that oxyhydroxides involved with sulfur species formed on the electrode surface during oxygen evolution process, while the hierarchical microstructure of the electrode keeps. Especially, the Fe-Co-S/Cu2O/Cu catalytic electrode shows excellent catalytic performance for salty water and real seawater splitting, and demonstrates excellent catalytic stability. This study provides an effective strategy towards the fabrication of metal sulfide electrode with hierarchical microstructure for water/seawater splitting.

Optical and electronic properties of lead sulfide spherical nano particle

In this paper optical and electronic properties of lead sulfide spherical nano particle are studied using the density functional theory. To this end, a lead sulfide unit cell with Fm-3 m(225) symmetry is converted to a 1 nm spherical nanocluster, and then is placed into a 2 nm supercell structure. Total density of state (DOS) and partial density of states (PDOS) are considered to study electronic properties. The highest energy level of the valence band and its lowest energy level originate from 3p of sulfur atom and 5d of Lead atom respectively. The absorption coefficient, conductivity, dielectric function, loss function, reflective index, and reflectivity spectrum are studied to investigate optical properties for radiation power up to 35 eV. The analyses identify that the imaginary part of dielectric function has two main regions representing the ohmic resistance of PbS at the regions. The real part of the dielectric function has a static dielectric constant of 6.5 (ε(0) = 6.4) representing the plasma frequency of lead sulfide spherical nano particle. Moreover, the material has maximum light absorption for photons with 10 eV energy which relates to the ultraviolet spectrum. However, it shows considerable absorption for photons with 5 eV and 30 eV energy. The static refractive index is found to be 2.5 (n(0) = 2.5) and maximum refractivity occurs in the visible region for photons with energy less than 3 eV. Analysis of the conductivity of lead sulfide spherical nano particle shows that it is a semiconductor material with a significant loss for photons with 2−6 eV energy at the visible range.

Functions of phenyl sulfide in polyimide as the electrode coating film to suppress the metal-particle motion within DC GIL

Polyimides containing diphenyl sulfide units were directly coated on the Aluminum electrodes via solution polycondensation-thermal imidization method, which is important for suppression of the free metal particle motion in the Direct Current Gas Insulation Transmission Line (DC GIL). The micro-structures were identified by Fourier-transform infrared spectroscopy (FT-IR). A self-designed experimental platform with plate-to-plate electrode configuration was constructed, by which the metal particle motion behaviors were traced and studied under high voltage DC stresses. To clarify the functionality of phenyl sulfide in the polyimide, the physicochemical properties including thermal and dielectric properties as well as adhesion works were tested accordingly. The microscopic interactive scenarios between polyimides and the electrodes were elucidated by reactive force field molecular dynamics (ReaxFF MD) simulations. The experimental and simulated results were correlated, and also compared with that from the non-sulfur contained polyimide specimen. For the spherical Aluminum particles, a significantly improved DC lifting voltage up to 21.12 kV was achieved by the sulfur-contained polyimide coating, due to the fact that sulfur in the polyimides will increase the dielectric constant as well as the adhesion strength with metal particles. Also, the changes in bulk conductivity are correlated more closely to the variation of particle-motion behaviors after being lifted in the DC electric field. The observed results show that, the inclusion of sulfur element can effectively enhance the adhesion between the polyimide film and the DC GIL Aluminum electrode, as sulfur in the diamine structure of polyimide is more likely to bind with Aluminum than oxygen.

Synthesis of π‐conjugated polymer containing both thiophene and phosphole sulfide in the main chain by simultaneous post‐element transformation of organotitanium polymer

ABSTRACTThe synthesis and unique optoelectronic features of a π‐conjugated polymer containing both thiophene and 1‐phenylphosphole sulfide units (multiple heteroles) in the main chain by the post‐element transformation of a regioregular organometallic polymer possessing titanacyclopentadiene‐2,5‐diyl unit are described. The π‐conjugated polymer containing multiple heteroles was obtained in 73% yield by the simultaneous reaction of the organotitanium polymer with sulfur monochloride and dichlorophenylphosphine (0.6 equiv each), whose number‐average molecular weight (Mn) and the molecular‐weight distribution (Mw/Mn) were estimated to be 11,000 and 3.4, respectively, by the size exclusion chromatography (SEC). The π‐conjugated polymer thus obtained was found to have the high HOMO and the low LUMO energy levels due to the electron‐rich thiophene and electron‐deficient phosphole sulfide units, respectively, as supported by its cyclic voltammetry (CV) analysis. Compared to a mixture of a polymer containing sole thiophene‐unit and that containing sole phosphole sulfide units, the π‐conjugated polymer‐containing multiple heteroles proved to exhibit interesting optical properties. For example, a specific emission peak was observed at 608 nm in the photoluminescence spectrum, which was not observed in the case of the thiophene‐containing polymer, the phosphole‐containing polymer, and their mixture. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2519–2525

Effects of 2,5-furanylene sulfides in polymer main chains on polymer physical properties

We developed 2,5-furanylene sulfide-containing polymers bearing different spacers as repeating units and evaluated the interactions between the furanylene sulfide units in the polymers. The treatment of 2,5-dichlorofuran derivatives with dithiolates at 200 °C promotes polycondensation via nucleophilic aromatic substitution to give the corresponding furanylene sulfide-containing polymers. Tensile measurements and spectral analyses demonstrate that the furanylene sulfide moieties form remarkably stable π–π stacking structures based on the enhanced dipole moment induced by sulfur linkages. When the polymer has a long spacer between repeating furanylene sulfide units, the polymer behaves as a chemically stable network polymer comprised of π–π stacking structures as cross-linking units. We developed 2,5-furanylene sulfide-containing polymers bearing different spacers as repeating units and evaluated the interactions between the furanylene sulfide units in the polymer. Treatment of a 2,5-dichlorofuran derivative with dithiolates at 200 °C promotes polycondensation via nucleophilic aromatic substitution to give the corresponding furanylene sulfide-containing polymers. Through tensile measurements and spectral analyses, it was found that the furanylene sulfide moieties form remarkably stable π–π stacking structures based on the enhanced dipole moment induced by sulfur linkages. When the polymer has a long spacer between repeating furanylene sulfide units, the polymer behaves as a chemically stable network polymer comprised of π–π stacking structures as cross-linking units.

Relationship between hydrogen sulphide and odour units for London sewage

Relationship between hydrogen sulphide and odour units for London sewage

Aliphatic polycarbonate-based thermoplastic polyurethane elastomers containing diphenyl sulfide units

New thermoplastic polyurethane elastomers (TPUs) were obtained by a one-step melt polyaddition from 30, 45 and 60 mol% aliphatic polycarbonate diol of M n = 2000 g mol−1 (Desmophen® C2200, Bayer), 1,1′-methanediylbis(4-isocyanatocyclohexane) (HMDI) or 1,6-diisocyanatohexane (HDI) and 2,2′-[sulfanediylbis(benzene-1,4-diyloxy)]diethanol (acting as a chain extender). The TPUs were examined by FTIR, UV–Vis, atomic force microscopy, X-ray diffraction analysis, differential scanning calorimetry, thermogravimetry (TG) and TG–FTIR. Moreover, their Shore A/D hardness, tensile, adhesive and optical properties were determined. The obtained TPUs were transparent or opaque high molar mass materials, showing amorphous or partially crystalline structures. The HDI-based TPUs exhibited lower glass-transition temperatures than those based on HMDI (from −35 to −31 °C vs. from −20 to 1 °C) as well as a higher degree of microphase separation. The TPUs were stable up to 262–272 °C, taking into account the temperature of 1 % mass loss, with somewhat higher values shown by those from HDI. They decomposed in two stages. The main volatile products of the hard-segment decomposition were carbon dioxide, water and carbonyl sulfide, while aliphatic ethers, aldehydes and unsaturated alcohols, as well as carbon dioxide, originated from the soft-segment decomposition. The synthesized TPUs, with hardness in the range of 80–90°Sh A, possessed a good tensile strength (33.0–38.7 MPa), similar to that of the commercial biodurable medical grade TPU ChronoFlex® AL 80A (37.9 MPa), prepared from aliphatic polycarbonate diol, HMDI and butane-1,4-diol.

Novel anti-oxidative membranes based on sulfide-containing polybenzimidazole for high temperature proton exchange membrane fuel cells

The introduction of sulfide units is a potential strategy to improve solubility and processibility of polybenzimidazole (PBI) polymer, as well as to enhance antioxidant capacity of corresponding membrane. In this paper, the novel S-PBI-x serial copolymers (x denotes the percentage of sulfide-containing monomer) were prepared by a microwave-assisted tetracopolymerization with 3,3′,4,4′-tetraaminobiphenyl, 2,6-pyridinedicarboxylic acid, hexanedioic acid and the synthesized methyl 3-((2-methoxy-2-oxoethyl)thio)propanoate as copolymerized monomers in different proportion. The resultant copolymers were characterized by FT-IR, GPC and energy dispersive spectroscopy. These sulfide-containing copolymers exhibit much better solubility in aprotic solvents such as N,N-dimethylacetamide, N,N-dimethylformamide and dimethylsulfoxide than unmodified PBI. The oxidative stability of the membranes was studied by enhanced Fenton test (20% H2O2 and 4ppm Fe2+, 80°C, refreshed every 3h). Additionally, the oxidized membranes were further characterized by FT-IR, TGA, and tension test. The experimental results show that S-PBI-7% membrane suffers less than 5% weight loss after 24h of treatment with enhanced Fenton reagent. Typically, after treated in enhanced Fenton reagent, the oxidized S-PBI-7% membrane still retains considerable thermal stability and mechanical strength. The anti-oxidative mechanism of the prepared membranes was discussed as well.

Volcanological and Structural Controls on Mineralization at the Mount Keith and Cliffs Komatiite-Associated Nickel Sulfide Deposits, Agnew-Wiluna Belt, Western Australia—Implications for Ore Genesis and Targeting

The Mount Keith region of the Agnew-Wiluna belt in Western Australia is perhaps best known for hosting the giant komatiite-associated disseminated Ni sulfide deposit known as MKD5. It also hosts the sizeable Cliffs massive Ni sulfide deposit, which is the eighth largest in the Archean Yilgarn block. A concerted program of regional-scale three-dimensional model construction has integrated a plethora of geological, geochemical, and geophysical data and led to a much better understanding of the tectonic and volcanic architecture of this ancient greenstone belt. The disseminated MKD5 orebody occupies a curvilinear thickening in the olivine adcumulate core of the host Mount Keith ultramafic unit. The orebody plunges shallowly to the south from surface, over a distance of 3.5 km, before bending sharply to plunge steeply to the north-northwest at depth. The thickest part of the orebody and the best Ni grades are associated with the bend in the overall ore trend. This also marks the approximate intersection point of two growth faults that appear to control the thickness variations in the adcumulate core and the plunge variations in the ore trend. The olivine adcumulate core is mantled by olivine orthocumulate rocks, which are best developed above and below the flanks of the orebody, and a fractionated sequence of pyroxenitic and gabbroic rocks occurs at the top of the Mount Keith ultramafic unit above the inside of the bend in the ore trend. These observations suggest a strong volcanological control on the position of the MKD5 orebody, and the local curvilinear thickening in the adcumulate core is interpreted as a fluid pathway, the locus of which was in turn controlled by the intersection of two broadly orthogonal growth faults. The Cliffs ultramafic unit consists of a lower olivine ortho- to mesocumulate unit, which varies in thickness along strike, overlain by a sequence of thin, spinifex-textured komatiite flow units intercalated with variably sulfidic tuffaceous shales. The Cliffs massive Ni sulfide deposit occurs at the base of a relative thickening (to ~100 m) in the lower olivine ortho- to mesocumulate unit. The orebody is typically less than 6 m thick, 500 m wide and plunges gently south from surface over a distance of 1.5 km, terminating in a structurally complex zone across which there are marked differences in the internal stratigraphy and thickness of the Cliffs ultramafic unit. The orebody has relatively low tenor (maximum ~8% Ni, typically ~5% Ni) and the tenor is strongly zoned with extremely low tenors (1–3% Ni) developed on the flanks. A barren exhalative massive Fe sulfide unit is typically present at the base of the Cliffs ultramafic unit on the flanks of the orebody and probably acted as a source of sulfur. The tenor zonation pattern suggests that the melting and entrainment of the underlying exhalative sulfide horizon occurred more vigorously in the center of the lava pathway. The structurally complex zone at the southern end of the Cliffs orebody is interpreted as a possible vent location; this would explain the relatively low tenor of the orebody and the tenor zonation (through limited mixing and entrainment of melted exhalative iron sulfide melt with the komatiite lava), the poorly incised nature of the lava pathway and the abrupt change in internal komatiite stratigraphy across this zone. There is good evidence that the southern terminations of both the MKD5 and the Cliffs orebodies are marked by growth faults. At a belt scale these points correspond roughly with the intersection of NNE- and NW-trending lineaments. These lineaments are on the order of 5 to 10 km in strike length and are visible in regional geophysical datasets (both gravity and magnetics). They are likely to mark the position of accretionary structures that were active at the time of volcanism and that probably controlled the volcanic architecture of the komatiite flow field and the location of Ni sulfide accumulations within komatiite lava pathways. Repeated reactivation of these early crustal-scale structures during subsequent orogenesis resulted in their upward propagation as sets of late brittle structures. Of broader significance to the understanding of the generation of komatiite-associated nickel sulfide deposits is the conclusion that many such deposits may be developed proximal to vent rather than in a distal setting, as has been proposed for the Kambalda camp.

An Unexpected Access to a New Sphingoid Base Containing a Vinyl Sulfide Unit

An unexpected access to a new sphingoid base containing a vinyl sulfide unit is described. The process involves the ‘one-pot’ regioselective opening of an epoxide with a thiolate, followed by intramolecular acyl transfer, base-promoted elimination, and final hydrolysis. Excess sodium hydride and high dilution conditions are required for optimal yields. The process is amenable to a variety of thiolates. The resulting compounds can be regarded as new hybrid sphingoid bases that combine some structural motifs present in other reported sphingolipid analogues.

Reversible aqueous metathesis reactions for potential application in dynamic combinatorial chemistry

Solutions of heterocycles having an allyl sulfide unit and simple alkenes in 50% t-BuOH/H 2O undergo reversible olefin metathesis reactions with the second generation Hoveyda–Grubbs catalyst. The choice of functional groups is limited by competitive chelation of some heterocycles with the catalyst, and other stereoelectronic effects.