Radical 1,5-Chloropentafluorosulfanylation of Unactivated Vinylcyclopropanes and Transformation into α-SF5 Ketones.

The radical 1,5-chloropentafluorosulfanylation of vinyl cyclopropanes (VCPs) initiated by Et3B/O2 affords allylic pentafluorosulfanyl/homoallylic chloride products through the ring-strain release of the cyclopropane. The VCP substitution pattern was investigated. The utility of this reaction was illustrated in post-transformation of the C═C bond by ozonolysis, giving access to valuable α-SF5 carbonyl compounds.

General Synthesis of Tri-Carbo-Substituted N2-Aryl-1,2,3-triazoles via Cu-Catalyzed Annulation of Azirines with Aryldiazonium Salts.

The general synthesis of fully substituted N2-aryl-1,2,3-triazoles is hitherto challenging compared with that of the N1-aryl counterparts. Herein, we describe a Cu-catalyzed annulation reaction of azirines and aryldiazonium salts. This regiospecific method allows access to a broad spectrum of tri-carbo N2-aryl-1,2,3-triazoles substituted with diverse aryl and alkyl moieties. Its utility is highlighted by the synthesis of several triazole precursors applicable in drug discovery, as well as novel chiral binaphthyl ligands bearing triazole moieties.

Constructing a CdS QDs/silica gel composite with high photosensitivity and prolonged recyclable operability for enhanced visible-light-driven NADH regeneration.

Visible-light-driven nicotinamide adenine dinucleotide (NADH) regeneration is one of the most effective measures, and cadmium sulfide (CdS) materials are typically used as low-cost photocatalysts. The CdS photocatalysts, however, still suffer from low regeneration efficiency and poor cycle stability. In this work, the CdS quantum dots (QDs) less than 10 nm embedded onto silica gel (CdS QDs/Silica gel) were constructed for visible-light-driven NADH regeneration by a successive ionic layer adsorption reaction and ball milling method. Results demonstrate that the photosensitivity of the CdS QDs/Silica gel composite was 31 times higher than that of the bulk CdS. Moreover, the conduction band (CB) edge of the CdS QDs/Silica gel composite is -1.34 eV, which is more negative 0.5 eV than that of the bulk CdS. The obtained CdS QDs/Silica gel composites showed the highest NADH regeneration yields of 68.8% under visible-light (LED, 420 nm) illumination and can be reused for over 40 cycles. Finally, the bioactivity of NADH toward enzyme catalysis is further confirmed by the hydrogenation of benzaldehyde to benzyl alcohol catalyzed with an alcohol dehydrogenase as enzyme catalysis.

Establishing a rabbit model of perianal fistulizing Crohn's disease.

BACKGROUND: Crohn's disease (CD) is a chronic nonspecific intestinal inflammatory disease. The aetiology and pathogenesis of CD are still unclear. Anal fistula is the main complication of CD and is a difficult problem to solve at present. The main limitation of developing new therapies is bound up with the short of preclinical security and effectiveness data. Therefore, an ideal animal model is needed to establish persistent anal fistula and an inflamed rectal mucosa. AIM: To improve the induction method of colitis and establish a reliable and reproducible perianal fistulizing Crohn's disease animal model to evaluate new treatment strategies. METHODS: Twenty male New Zealand rabbits underwent rectal enema with different doses of 2,4,6-trinitrobenzene sulfonic acid to induce proctitis. Group A was treated with an improved equal interval small dose increasing method. The dosage of group B was constant. Seven days later, the rabbits underwent surgical creation of a transsphincteric fistula. Then, three rabbits were randomly selected from each group every 7 d to remove the seton from the fistula. The rabbits were examined by endoscopy every 7 days, and biopsy forceps were used to obtain tissue samples from the obvious colon lesions for histological analysis. The disease activity index (DAI), colonoscopy and histological scores were recorded. Perianal endoscopic ultrasonography (EUS) was used to evaluate the healing of fistulas. RESULTS: Except for the DAI score, the colonoscopy and histological scores in group A were significantly higher than those in group B (P < 0.05). In the ideal model rabbit group, on the 7th day after the removal of the seton, all animals had persistent lumens on EUS imaging, showing continuous full-thickness high signals. Histological inspection of the fistula showed acute and chronic inflammation, fibrosis, epithelialization and peripheral proctitis of the adjoining rectum. CONCLUSION: The improved method of CD colitis induction successfully established a rabbit perianal fistula CD preclinical model, which was confirmed by endoscopy and pathology.

Cu-Enabled [3 + 2] Annulation of In Situ Formed Nitrile Ylides with Aryldiazonium Salts: Access to 5-Cyano-1,2,4-Triazoles.

The unified construction of cyano-substituted 1,2,4-triazoles, particularly the 5-cyano counterparts, remains underdeveloped. Herein we describe a three-component method to access a wide range of 1-aryl 5-cyano-1,2,4-triazoles using readily available 2-diazoacetonitriles, nitriles, and aryldiazonium salts. This regiospecific synthesis relies on the dipolar [3 + 2] annulation of the in situ formed nitrile ylides with aryldiazonium salts. Furthermore, this protocol can be amendable to gram-scale synthesis, chemical transformations of the nitrile moieties, and access to chiral bis(cyano-triazole)-1,1'-naphthalene, which would all be likely applicable in the synthesis of structurally diverse bioactive compounds and novel bidentate ligands for asymmetric catalysis.

Switching of Enantioselectivity in the Cu-Catalyzed Asymmetric Decarboxylative Aldol Reaction of Tryptanthrin with ß-Keto Acids: An Unexpected Counteranion Effect.

Cu-bisoxazoline-catalyzed enantioselective decarboxylative aldol reaction of tryptanthrin with aryl-substituted ß-keto acids is developed, providing a straightforward approach to deliver a series of phaitanthrin A analogues. Both enantiomers of the products can be obtained with good to high enantioselectivity in the presence of a single chiral ligand by simply changing the copper salts. Based on the X-ray crystallographic analysis of chiral Cu(II)-bisoxazoline complexes, the tentative stereochemical models are presented to account for the observed counteranion-induced switching in enantioselectivity.

Chiral ß-Keto Propargylamine Synthesis via Enantioselective Mannich Reaction of Enamides with C-Alkynyl N-Boc N,O-Acetals.

Propargylamines are an important class of compounds in organic synthesis and drug discovery, yet the synthesis of chiral ß-keto propargylamines remains underdeveloped. Herein, we describe a streamlined and general enantioselective Mannich reaction of enamides with C-alkynyl N-Boc N,O-acetals, which serve as readily available C-alkynyl imine precursors, to access a broad range of chiral ß-keto N-Boc-propargylamines bearing single stereogenic centers in high yields (up to 98%) and in high enantioselectivities (up to 95% ee).

[Effects of drought and rewatering on leaf photosynthesis, chlorophyll fluorescence, and root architecture of citrus seedlings.] / å¹²æ—±å¤æ°´å¯¹æŸ‘æ©˜å¹¼è‹—å¶ç‰‡å ‰åˆã€å¶ç»¿ç´ è§å ‰å’Œæ ¹ç³»æž„åž‹çš„å½±å“.

Drought severely affects citrus growth and development. In order to explore the mechanism of drought response of citrus, two cultivars (Sanhuhongju and Sanhuhuahong) that differing in drought tolerance were used as materials. The drought and rewatering treatment was conducted in pot experiments, with leaf photosynthesis, chlorophyll fluorescence, and root architecture being measured. The results showed that drought significantly decreased net photosynthetic rate (Pn), stomatal conductance (gs), transportation rate (Tr), and intercellular CO2 concentration (Ci) of both cultivars, but Sanhuhongju generally showed less reduction. After rewatering, photosynthetic parameters were partly recovered but still lower than that in control. The water use efficiency (WUE) of Sanhuhongju was significantly increased after drought stress for 15 d, but the WUE of Sanhuhuahong was decreased except at the 15 day of drought stress. In addition, the maximum photosynthesis efficiency of PS II (Fv/Fm) was increased in both cultivars, but the photochemical quantum yield of PS II [Y(II)] was increased in Sanhuhuahong under drought. Both the apparent electron transport rate (ETR) and photochemical quenching (qP) were inhibited in the treated seedlings. The non-photochemical quenching (NPQ) was decreased in Sanhuhongju while increased in Sanhuhuahong under drought and rewatering conditions. Drought stress resulted in the decrease of root surface area and volume of both cultivars, and it inhibited root elongation of Sanhuhuahong while improved the root length and root tip number of Sanhuhongju. The length of first lateral roots of Sanhuhongju was increased after drought stress 10 d, but did not change at the drought stress prophase of Sanhuhuahong, and then significantly decreased after 20 d. Furthermore, drought stress inhibited all lateral roots development except the tertiary lateral root of Sanhuhongju, and root growth could not be recovered by rewatering except root tip number. In conclusion, Sanhuhongju showed less reduction in leaf photosynthesis than Sanhuhuahong, with higher WUE and light use efficiency under drought stress. The increases of root tip number and lateral root length would help improve water uptake ability in Sanhuhongju.

Osteoblastic cell response on biphasic fluorhydroxyapatite/strontium-substituted hydroxyapatite coatings.

Fluorhydroxyapatite/strontium-substituted hydroxyapatite (FHA/SrHA) biphasic coatings with F and Sr elements incorporated simultaneously into one coating layer were prepared on titanium substrate via colloidal sol-gel method. The bioactivity of the as-prepared FHA/SrHA biphasic coatings was evaluated in vitro by immersion in simulated body fluid (SBF). All the biphasic coatings exhibited great ability to induce apatite precipitation on their surfaces. In vitro cell responses were evaluated using osteoblast-like MG63 cells in terms of cell proliferation and differentiation (alkaline phosphatase activity and osteocalcin level). The biphasic coatings show significantly positive effects on the viability and functional activity of osteoblastic cells with clear evidence that an optimum SrHA amount dose exists, indicating that the coexistence of FHA and SrHA had a synergistic stimulatory effect. This finding suggests the potential use of this colloidal sol-gel derived FHA/SrHA biphasic coatings for hard tissue applications.