Synergistic Pd/Cu catalysis enabled cross-coupling of glycosyl stannanes with sulfonium salts to access C-aryl/alkenyl glycals

A highly efficient coupling of glycosyl stannanes and sulfonium salts enabled by synergistic Pd/Cu catalysis is disclosed, facilitating the construction of C-aryl/alkenyl glycals under mild conditions in high yields.The protocol tolerates a wide scope of functional groups including ketone, cyano, ester, amide, nitro,halide. The one-pot formal C–H glycosylation starting from arene is demonstrated with a reaction sequence of dibenzothiophenylation/Stille coupling. Besides, a gram-scale reaction is performed successfully,showing the high applicability of this protocol.

Copper-Catalyzed Highly Stereoselective Hydrodifluoroallylation of Cyclopropenes and Alkenyl Boronates with 3,3-Difluoroallyl Sulfonium Salts

Despite the paramount applications of organofluorine compounds in life and materials sciences,efficient strategies for stereoselectively constructing the C(sp^(3))-CF_(2)R bond at the stereogenic center remain limited.Here,we report a copper-catalyzed hydrodifluoroallylation of cyclopropenes and alkenyl boronates with 3,3-difluoroallyl sulfonium salts(DFASs).The use of DFASs overcomes the previous challenge of suppressing the reduction of fluoroalkylating reagents with M-H species.The reaction provides an array of gem-difluoroallyl cyclopropanes and borylalkanes with high efficiency and stereoselectivity under mild reaction conditions.Using chiral phosphine ligand could provide gem-difluoroallyl borylalkanes with high enantioselectivities,paving a new way for the catalytic asymmetric fluoroalkylation with ubiquitous alkenes.The advantages of this protocol are synthetic convenience,high functional group tolerance,and the synthetic versatility of the resulting gem-difluoroallyl cyclopropanes and borylalkanes.The synthetic utility of this approach has also been demonstrated by the diversified transformations of the gem-difluoroallylated products and the rapid synthesis of bioactive molecule analogs.

Anti-Markovnikov ring-opening of sulfonium salts with alkynes by visible light/copper catalysis

Internal alkynes are widespread skeletons in bioactive molecules and materials which are also used as important building blocks in chemical synthesis. Herein, we report a novel and efficient copper-catalyzed Sonogashira reaction between sulfonium salts and alkynes through an anti-Markovnikov ring-opening pathway promoted by visible light. The coexistence of the nitrogen and phosphorus ligands in the system is the key to the success of this reaction. This radical type ring-opening reaction affords a new strategy for the synthesis of internal alkynes. Furthermore, this study is also an effective complement to the diverse reaction patterns of sulfonium salts.

Multistimuli responsive supramolecular polymer networks via host-guest complexation of pillararene-containing polymers and sulfonium salts

A stimuli-responsive supramolecular polymer network has been constructed based on the host-guest interactions between the copolymer poly-P[5]A with pendent pillararene units and bis(sulfonium)diction guest G2.The formation mechanism of the supramolecular polymer network has been explored by the intensive study.With the addition of the competitive molecules and heating,the supramolecular polymer network could be dissociated and lead to clear changes in NMR spectroscopy and viscosity property.

Synthesis,characterization,and antioxidant activity of carboxymethyl chitosan derivatives containing sulfonium salt

To improve the solubility and bioactivity of chitosan,a new class of carboxymethyl chitosan derivatives possessing sulfonium salts was successfully designed and synthesized,including Methyl sulfi de carboxymethyl chitosan(MCMCS),Ethyl sulfi de carboxymethyl chitosan(ECMCS),Propyl sulfi de carboxymethyl chitosan(PCMCS),and Butyl sulfi de carboxymethyl chitosan(BCMCS).To determine the structure of the new class of the derivatives,methods of the Fourier transform infrared spectroscopy(FT-IR),^(1)H nuclear magnetic resonance spectrometer(^(1)H NMR),and^(13)C nuclear magnetic resonance spectrometer(^(13)C NMR)were used.Moreover,the antioxidant activity of the derivatives for three types of free radicals,i.e.,hydroxyl radical,superoxide radical,and 1,1-diphenyl-2-picrylhydrazyl(DPPH)radical was evaluated in vitro.In addition,the L929 cells were adopted to test the cytotoxicity of chitosan and its derivatives by CCK-8 assay.The class of the carboxymethyl chitosan derivatives showed a strong scavenging ability against the three free radicals at 1.6 mg/mL,with scavenging rate of over 70%and some up to 100%.At this high rate,the overall cell viability in the toxicity test reached more than 80%,indicating that the synthetic derivative had a little cytotoxicity.The results show that the introduction of carboxymethyl group to chitosan increased the water-solubility of chitosan,and the combination of sulfonate ions with diff erent chain lengths further enhanced the antioxidant activity of chitosan.Therefore,the sulfonium-containing carboxymethyl chitosan derivatives had excellent bioactivity with good application prospects in food,biomedicine,and medical fi elds.

Preparation of Aryl-Substituted Sulfonium by Condensation of Biphenyl Sulfoxides with Aromatic Compound

Three kind of aryl-substituted tri-benzyl sulfonium salts [ （4-phX）phSph2 ] PF6 [ X = S, O ] were prepared by the condensation of biphenyl sulfoxide with biphenyl sulfide, biphenyl ether or 1, 1＇ -biphenyl in the presence of polyphosphoric acid which can be used as dehydrate agent. The reaction condition was mild, such as reaction temperature between 40- 50 ℃ ,reactive time 2- 3 h, the yield of 4-（phenylthio）triphenylsulfonium hexafluorophosphate was 87.6%. The three kind sulfonium salts show better curing character to epoxy resin.

Effects of Conjugated Systems on UV-Visible Light-sensitive D-π-A Type Sulfonium Salt Photoacid Generators

A series of D-π-A type sulfonium salt photoacid generators with different π-conjugated structures, such as triphenyl, phenylstilbene, styryl-biphenyl, and stilbene, were designed to determine the effect of molecular structures on the photochemical and photophysical properties. The mechanisms of photochemical generation of H＋ were studied by UV-Vis spectroscopy, theoretical calculations, and fluorescence spectroscopy. It is found that the frontier orbits determine the absorption, the molar extinction coefficients, and the quantum yields of photoacid generation. Triphenyl systems connected with sulfonium are beneficial to increase the quantum yields of acid generation. The photoreactivity of four sulfonium salts was further evaluated through the polymerizations of various epoxide monomers at different irradiation wavelengths （365- 425 nm） by using the real-time infrared spectroscopy with light-emitting diodes. The high quantum yields for acid generation （ФH＋ = -0.32 to 0.58） and the high molar extinction coefficients （ε = -23500 L.mol-1.cm-1 to 31000 L.mol-1.cm-1） of the sulfonium salts lead to high conversion rates （over 50%-80%）. Hence, these photoinitiators exhibit potential for the photocuring applications.