ABSTRACT
Alkenylboronates are highly versatile building blocks and valuable reagents in the synthesis of complex molecules. Compared with that of monosubstituted alkenylboronates, the synthesis of multisubstituted alkenylboronates is challenging. The copper-catalyzed carboboration of alkynes is an operationally simple and straightforward method for synthesizing bis/trisubstituted alkenylboronates. In this work, a series of copper-metallized N-Heterocyclic Carbene (NHC) ligand porous polymer catalysts are designed and synthesized in accordance with the mechanism of carboboration. By using CuCl@POL-NHC-Ph as the optimal nanocatalyst, this study realizes the ß-regio- and stereoselective (syn-addition) 1,2-carboboration of alkynes (regioselectivity up to >99:1) with satisfactory yields and a wide range of substrates. This work not only overcomes the selectivity of carboboration but also provides a new strategy for the design of nanocatalysts and their application in organic synthesis.
ABSTRACT
In general, halogenide anions are anodically oxidized into active species, which can be elemental halogen, halogen cations, or halogen radicals. These species subsequently react with substrates, such as olefins, ketones, or amines, to generate halogenated products. We review the mechanisms of these reactions.
ABSTRACT
<p><b>OBJECTIVE</b>To study the relationships among pathological and immunohistochemical changes in liver tissues, and the HBeAg, HBV DNA, ALT level in the patients with chronic hepatitis B.</p><p><b>METHODS</b>Pathological and immunohistochemical examinations of liver tissue liver function tests, serum HBV and HBV DNA detection were performed in 194 patients with chronic hepatitis B.</p><p><b>RESULTS</b>There was significant difference between the serum HBeAg positive group and the negative group in G2, G3-4 S2, S3-4 in liver tissues; The serum HBV DNA level of the groups S0 and S1-4, and the hepatic activity index between the groups G0-1 and G2-4 were significantly different. And the hepatic HBcAg positive group and HBcAg negative group were significantly different too. There was no significant difference between the HBsAg level in liver tissues as "+" group and the "++ - +++" group. The pathological diagnosis as S1 or (and) G2 is respectively 28.57%, 53.33%, 80.15%, 77.88% among the four groups with normal-mild-moderate-severe elevated serum ALT level.</p><p><b>CONCLUSION</b>Serum HBV DNA correlated with HBcAg expression in liver tissue; the HBsAg level in liver tissues have no relationship with the serum HBV DNA level. The patients with low serum HBV DNA level may have high index of hepatic activity and hepatic fibrosis. Asymptomatic carriers and patients with low serum ALT level should be encouraged to accept liver biopsy. It can determine the degree of liver inflammation and fibrosis and timing of treatment.</p>
