An efficient synthesis of pyrazoles from tosylhydrazones and nitroalkenes was developed. In comparison with the previously reported 1,3-dipolar cycloaddition reaction of diazo compounds with electron-deficient alkenes or alkynes, this methodology proceeded with a sequential Baylis-Hillman/intramolecular cyclization mechanism and a variety of reversed regioselectivity products were prepared in good yields.
An efficient synthesis of 1,3,5-trisubstituted pyrazoles from N-alkylated tosylhydrazones and terminal alkynes was developed. The protocol was applied to a wide range of substrates and demonstrated excellent tolerance to a variety of substituents, including both electron-donating and -withdrawing groups. In comparison with the common approaches for substituted pyrazole syntheses, this methodology proceeded with complete regioselectivity, especially, in the cases that R(2) and R(3) are similar substituents.
An efficient synthesis of indazoles from readily accessible E/Z mixtures of o‐haloaryl N‐tosylhydrazones has been developed. The thermo‐induced isomerization of N‐tosylhydrazones is discussed. A series of valuable indazole derivatives are prepared in good yields, and the method has been successfully applied to the synthesis of the bioactive compounds, lonidamine, AF‐2785, axitinib, YC‐1 and YD‐3.magnified image
A metal‐free photo redox C–H trifluorometlylation of imidazopyridines is described. The reaction is operationally simple and the easy‐handling CF3SO2Na serves as an effective fluoroalkyl radical precursor. Various functional groups were tolerated under blue LED light to access the desired products in satisfied yields at room temperature.
Rubus chingii Hu has been used as a functional food for a long time. A novel pectin polysaccharide named RCHP-S from R. chingii Hu was structurally identified and explored its anti-inflammatory effect on colitis mice. RCHP-S was composed of mannose, rhamnose, glucuronic acid, galacturonic acid, glucose, galactose, and arabinose. NMR spectroscopy and methylation analysis showed that RCHP-S was mainly composed of HG-type pectin domains but also contains a small amount of RG-I. The anti-inflammatory tests indicated that the mouse macrophage RAW 264.7 cells pretreated with RCHP-S could show a significant inhibitory effect on the mRNA level of iNOS, IL-1β, IL-6, and TNF-α in vitro. Polysaccharide RCHP-S reduced the enteritis symptoms in dextran sulfate sodium (DSS)-induced colitis mice by inhibiting released inflammatory factors. These results indicated that the R. chingii Hu polysaccharide can be used as food additives for the treatment of intestinal inflammation.
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