Tissue inhibitor of metalloproteinase-3 expression affects clinicopathological features and prognosis of aflatoxin B1-related hepatocellular carcinoma.

Background: The dysregulation of tissue inhibitor of metalloproteinase-3 (TIMP3) was positively correlated with the progression of hepatocellular carcinoma (HCC). However, it is not clear whether TIMP3 expression is associated with the clinicopathological features and prognosis of aflatoxin B1 (AFB1)-related HCC (AHCC).

Aim: To assess the effects of TIMP3 expression on the clinicopathological features and prognosis of AHCC.

In situ quantitative analysis by ultrasonic extraction and nebulization combined with hydrogen flame ionization mass spectrometry: Diisopropylnaphthalene (DIPN), a marker of recycled paper in packing materials.

Ambient mass spectrometry is used for direct analysis and high-throughput screening in many fields. However, most researches are about qualitative analysis. Quantitative detection based on AMS only performs on standard compounds and the relative standard deviation is so large that the accuracy of the result is low.

Chrysene, a four-ring polycyclic aromatic hydrocarbon, induces hepatotoxicity in mice by activation of the aryl hydrocarbon receptor (AhR).

Polycyclic aromatic hydrocarbons (PAHs) are a group of persistent organic global environmental pollutants and cause harmful effects on human health. Here, we evaluated adverse effects of chrysene, which is a four-ring PAH and an important member of 16 priority PAHs, on the liver. Chrysene was detected in some common raw and cooked Chinese food samples.

Palladium-Catalyzed Regioselective Olefination of O-Acetyl Cyanohydrins.

A practical palladium-catalyzed ortho-olefination of O-acetyl cyanohydrins assisted by synergetic directing groups has been developed. Thus, a range of olefinated O-acetyl cyanohydrins were synthesized in moderate to good yields. The reaction occurs efficiently with high regioselectivity and with a satisfactory tolerance of functional groups.

Copper-Catalyzed Dehydrogenative Diels-Alder Reaction.

A practical and effective copper-catalyzed dehydrogenative Diels-Alder reaction of gem-diesters and ketone with dienes has been established. The active dienophiles were generated in situ via a radical-based dehydrogenation process, which reacted with a wide variety of dienes to afford various polysubstituted cyclohexene derivatives in good to excellent yields.

Palladium-catalyzed silaborative carbocyclizations of 1,6-diynes.

An addition/cyclization reaction of 1,6-diynes was developed for the synthesis of highly substituted 1,2-dialkylidenecycloalkanes. In this work, 1,6-diynes reacted with (dimethylphenylsilyl)pinacol-borane in the presence of a palladium catalyst to afford 1,2-dialkylidenecycloalkanes bearing silyl and boryl groups with a (Z,Z)-configuration in good to excellent yields. Moreover, the corresponding products could be easily converted into other synthetically useful compounds.

Chelation versus Non-Chelation Control in the Stereoselective Alkenyl sp C-H Bond Functionalization Reaction.

A hydroxy group chelation-assisted stereospecific oxidative cross-coupling reaction between alkenes was developed under mild reaction conditions. In the presence of palladium catalyst, the alkenes tethered with hydroxy functionality can couple efficiently with electron-deficient alkenes to form the corresponding multi-substituted olefin products. The hydroxy group on the substrate could play dual roles in reaction, acting as the directing group for alkenyl C-H bond activation and controlling the stereoselectivity of the products.

Palladium-Catalyzed Direct Intramolecular C-N Bond Formation: Access to Multisubstituted Dihydropyrroles.

A palladium-catalyzed intramolecular amination of alkenes with retention of olefin functionalization was achieved under mild reaction conditions. In the presence of palladium catalyst, the tosyl-protected amine can directly couple with a double bond to provide versatile dihydropyrrole derivatives in moderate to excellent yields.

Palladium-catalyzed difunctionalization of internal alkynes via highly regioselective 6-endo cyclization and alkenylation of enynoates: synthesis of multisubstituted pyrones.

An efficient Pd(II)-catalyzed difunctionalization reaction of internal alkynes is reported. In this reaction, various enynoates and electron-deficient alkenes were used for the syntheses of useful highly substituted pyrone derivatives via a 6-endo cyclization and subsequent alkenylation pathway. The corresponding products could be obtained in moderate to good yields under very mild reaction conditions.

Addition of optically pure H-phosphinate to ketones: selectivity, stereochemistry and mechanism.

Aromatic methyl ketones and cyclic asymmetric ketones underwent hydrophosphorylation with P-stereogenic H-P species in the presence of potassium carbonate to produce P,C-stereogenic tertiary α-hydroxyl phosphinates in excellent yields with up to 99 : 1 dr. The diastereoselectivity was induced by a reversible conversion of less stable stereomer of product to that of a more stable one via an equilibrium, which was confirmed by aldehyde/ketone exchanging reaction. Toward the exchange, aliphatic or aldehyde carbonyl were more active than aromatic or ketone carbonyls, respectively.