Primary liver cancer is a severe and complex disease, leading to 800000 global deaths annually. Emerging evidence suggests that inflammation is one of the critical factors in the development of hepatocellular carcinoma (HCC). Patients with viral hepatitis, alcoholic hepatitis, and steatohepatitis symptoms are at higher risk of developing HCC.
View Article and Find Full Text PDFAn asymmetric intramolecular hydroalkylation of unactivated internal olefins with tethered cyclic ketones was realized by the cooperative catalysis of a newly designed chiral amine (SPD-NH ) and Pd complex, providing straightforward access to either bridged or fused bicyclic systems containing three stereogenic centers with excellent enantioselectivity (up to 99 % ee) and diastereoselectivity (up to >20 : 1 dr). Notably, the bicyclic products could be conveniently transformed into a diverse range of key structures frequently found in bioactive terpenes, such as Δ -protoilludene, cracroson D, and vulgarisins. The steric hindrance between the Ar group of the SPD-NH catalyst and the branched chain of the substrate, hydrogen-bonding interactions between the N-H of the enamine motif and the C=O of the directing group MQ, and the counterion of the Pd complex were identified as key factors for excellent stereoinduction in this dual catalytic process by density functional theory calculations.
View Article and Find Full Text PDFThe oral delivery of protein-based drugs is of great significance, but faces various obstacles, including the deactivation of proteins by the low pH in the stomach and the high concentration of protease, poor transport through intestinal bio-barriers, . Herein, we present an acid-resistant metal-organic framework (MOF), NU-1000, in which insulin (Ins, a model protein) was loaded with high capacity (Ins@NU-1000) through the pseudo second-order kinetic model and Langmuir isotherm model. Ins@NU-1000 protects Ins from deactivation in the stomach acid environment and releases it in the intestine through the transformation of the micro-sized rod particles into spherical nanoparticles.
View Article and Find Full Text PDFA novel oxyallyl cation promoted semipinacol rearrangement of indole-type allylic alcohols was disclosed for the stereodivergent synthesis of spiro-indolines. A variety of spiro-indolines were obtained with moderate to good yields. Three contiguous stereocenters, two of which are vicinal quaternary centers, were effectively formed with good diastereoselectivity.
View Article and Find Full Text PDFWinter precipitation and soil freeze-thaw events have been predicted to increase in boreal regions with climate change. This may expose tree roots to waterlogging (WL) and soil freezing (Fr) more than in the current climate and therefore affect tree growth and survival. Using a whole-tree approach, we studied the responses of silver birch (Betula pendula Roth.
View Article and Find Full Text PDFA challenging direct asymmetric catalytic aerobic oxidative cross-coupling of 2-naphthylamine and 2-naphthol, using a novel Cu /SPDO system, has been successfully developed for the first time. Enantioenriched 3,3'-disubstituted NOBINs were achieved and could be readily derived to divergent chiral ligands and catalysts. This reaction features high enantioselectivities (up to 96 % ee) and good yields (up to 80 %).
View Article and Find Full Text PDFA novel chiral 1,5-N,N-bidentate ligand based on a spirocyclic pyrrolidine oxazoline backbone was designed and prepared, and it coordinates CuBr in situ to form an unprecedented catalyst that enables efficient oxidative cross-coupling of 2-naphthols. Air serves as an external oxidant and generates a series of C -symmetric chiral BINOL derivatives with high enantioselectivity (up to 99 % ee) and good yield (up to 87 %). This approach is tolerant of a broader substrates scope, particularly substrates bearing various 3- and 3'-substituents.
View Article and Find Full Text PDFSoil waterlogging is predicted to increase in the future climate in boreal regions due to increased precipitation. Snowmelt periods in winter may also become more common and further increase the amount of water in soil. It is not well known how waterlogging and soil freezing during winter affect the physiology, phenology and growth of trees.
View Article and Find Full Text PDFA novel metal-free double SO insertion/multicomponent bicyclization cascade of benzene-linked 1,7-diynes has been established by treatment with aryldiazonium tetrafluoroborates and DABCO-bis(sulfur dioxide) under redox-neutral conditions, providing a range of dual sulfone-containing naphtho[1,2-]thiophene 2,2-dioxides with generally high stereoselectivity. The reaction pathway is proposed to proceed through the sequence of arylsulfonyl-radical-induced 6-exo-dig/5-endo-trig bicyclization, H-abstraction, and diazotization.
View Article and Find Full Text PDFNew radical-triggered multi-component cyclizations of β-alkynyl propenones have been developed, leading to 50 examples of sulfonated 1-indenones with generally good yields and high levels of stereoselectivity. The oxidant-free azosulfonylation of β-alkynyl propenones with aryldiazonium salts and DABSO was realized under the neutral-redox conditions where TBHP enabled the direct selenosulfonylation of β-alkynyl propenones by combining sulfinic acids and diphenyl diselenide. This protocol features a broad substrate scope, high functional group tolerance and mild reaction conditions.
View Article and Find Full Text PDFA new silver-mediated 5-exo-dig cyclization of 2-alkynylbenzonitriles with disubstituted phosphine oxide and HO has been developed. The reaction enables multiple bond-forming events including C-P, C-C and C-O bonds under atmospheric conditions, leading to the concise and direct formation of 28 examples of phosphorus-containing 1-indenones with generally good yields.
View Article and Find Full Text PDFA new catalytic difluorohydration of β-alkynyl ketones using NFSI as the fluorinating reagent has been established, diastereoselectively furnishing a range of structurally diverse difluoride 1,5-dicarbonyl products through C(sp)-H fluorination. Notably, the sterically encumbered t-butyl functionality located at the α-position of the carbonyl group of substrates 1 showed excellent diastereoselectivity (up to >99 : 1 dr). The reaction enabled multiple bond-forming events including two C(sp)-F formation through Ag-catalysis to provide a highly efficient and practical method toward difluoride 1,5-dicarbonyls, some of which were successfully converted into difluorinated isoquinolines.
View Article and Find Full Text PDFIncreased risk of soil waterlogging in winter and spring at northern latitudes will potentially affect forest production in the future. We studied gas exchange, chlorophyll content index, chlorophyll fluorescence, nutrient concentration and biomass accumulation in 1-year-old silver (Betula pendula Roth) and pubescent birch (Betula pubescens Ehrh.) seedlings.
View Article and Find Full Text PDFA novel I-mediated benzannulation of 1,7-diyne-involved 1,4-oxo-migration was established, providing a range of unexpected 1-aroyl-2-naphthaldehydes with a 1,4-dicarbonyl unit. The resulting 1-aroyl-2-naphthaldehydes were successfully applied in the synthesis of benzo[e]isoindol-3-ones and benzo[e]benzo[4,5]imidazo[2,1-a]isoindoles using aromatic amines and benzene-1,2-diamines as nucleophiles, respectively. The mechanisms for the formation of these compounds were proposed.
View Article and Find Full Text PDFA new cascade three-component haloazidation of benzene-tethered 1,7-enynes for the formation of biologically interesting azidylated 3,4-dihydroquinolin-2(1H)-ones has been achieved under mild and metal-free conditions using TMSN3 as a N3 source and NIS (or NBS or NCS) as a halogen source. The reaction pathway involves in situ-generated azidyl radical-triggered α,β-conjugated addition/6-exo-dig cyclization/radical coupling sequence, resulting in successive multiple bond-forming events, including carbon-nitrogen, carbon-carbon, and carbon-halogen bonds to rapidly construct complex heterocyclic molecules. Furthermore, the resulting products would be useful building blocks in the discovery of lead compounds and other biologically interesting N3-containing heterocycles.
View Article and Find Full Text PDFA new cascade three-component halosulfonylation of 1,7-enynes for efficient synthesis of densely functionalized 3,4-dihydroquinolin-2(1H)-ones has been established from readily accessible arylsulfonyl hydrazides and NIS (or NBS). The reaction pathway involves in situ-generated sulfonyl radical-triggered α,β-conjugated addition/6-exo-dig cyclization/radical coupling sequence, resulting in continuous multiple bond-forming events including C-S, C-C and C-I (or C-Br) bonds to rapidly build up molecular complexity.
View Article and Find Full Text PDFA new metal-free bicyclization reaction of 1,7-enynes anchored by α,β-conjugates with arylsulfonyl radicals generated in situ from sulfonyl hydrazides has been established using tert-butyl hydroperoxide and tetrabutylammonium iodide. The reactions occurred through sulfonylation/6-exo-dig/6-exo-trig bicyclization/in situ desulfonylation/5-exo-trig cyclization/alkyl or alkenyl migration cascade mechanism to give benzo[j]phenanthridines regioselectively.
View Article and Find Full Text PDFThe warmer winters of the future will increase snow-melt frequency and rainfall, thereby increasing the risk of soil waterlogging and its effects on trees in winter and spring at northern latitudes. We studied the morphology of roots and leaves of 1-year-old silver birch (Betula pendula Roth) and pubescent birch (Betula pubescens Ehrh.) seedlings exposed to waterlogging during dormancy or at the beginning of the growing season in a growth-chamber experiment.
View Article and Find Full Text PDFYing Yong Sheng Tai Xue Bao
July 2007
Plant cold hardiness has complicated attributes. This paper introduced the research advances in establishing the dynamic models of coniferous trees cold hardiness, with the advantages and disadvantages of the models presented and the further studies suggested. In the models established initially, temperature was concerned as the only environmental factor affecting the cold hardiness, and the concept of stationary level of cold hardiness was introduced.
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