Although manganese oxide (MnO2) exhibits excellent activity in various oxidation reactions, especially for volatile organic compound oxidation, the origin of catalytic remains ambiguous and controversial. In this study, four types MnO2 catalysts with crystal phases corresponding to α-, β-, γ-, δ-MnO2 were synthesized, their properties HCHO C6H6 studied. α- γ-MnO2 found possess much better than δ- β-MnO2 catalysts, whereas exhibited best performance as compared other MnO2. Three kinds oxygen...

Because heat shock proteins have been shown to play a critical role in protecting cells from hyperthermia and other types of physiological stresses, it was interest determine what effect age caloric restriction on the ability regulate expression protein 70 (hsp70), most prominent evolutionarily conserved proteins. Caloric is only experimental manipulation known retard aging increase survival mammals. The hepatocytes isolated young/adult (4- 7-month-old) old (22- 28-month-old) male Fischer...

The nine-membered ring-bearing bicyclo[5.2.2]tetrahydrooxonines frameworks have enantioselectively been constructed via a tandem [3 + 2] cycloaddition/Cope rearrangement reaction of vinylethylene carbonates (VECs) with coumalates or pyrones. Under mild conditions, palladium-catalyzed asymmetric various substituted VECs and pyrones proceeds smoothly to produce the corresponding medium-sized heterocyclic compounds in high yields very enantioselectivities. Moreover, on gram scale further...

Abstract The enantioselective conjugated addition of tritylthiol to in situ generated ortho ‐quinone methides ( o ‐QMs) is catalyzed by an acid–base bifunctional squaramide organocatalyst. transformation proceeds with high yield (up 99 %) and stereoselectivity 97:3 e.r.) using water as solvent under mild conditions. catalyst system provides a new strategy for the synthesis optically active benzyl mercaptans. Control experiments suggested that ‐QMs are tertiary amine moiety organocatalyst...

Abstract This paper proposes an attention-based LSTM (AT-LSTM) model for financial time series prediction. We divide the prediction process into two stages. For first stage, we apply attention to assign different weights input features of at each step. In second feature is utilized effectively select relevant sequences as neural network in next frame. Our proposed framework not only solves long-term dependence problem effectively, but also improves interpretability methods based on network....

Abstract The enantioselective α‐addition of deconjugated butenolides has rarely been exploited, in contrast to the well‐studied γ‐addition butenolides. In this study, an unprecedented asymmetric α‐addition/transesterification with ortho ‐quinone methides generated situ afforded a series functionalized 3,4‐dihydrocoumarins containing two contiguous stereogenic centers excellent diastereo‐ and enantioselectivity. DFT calculations suggested that observed regioselectivity was due distortion...

Atomically dispersed Ru atoms crowding on CeO₂ was used for the chemoselective hydrogenation of nitrobenzene to azoxybenzene by molecular hydrogen, which presented more than 88% selectivity with high stability.

Direct selective methane photooxidation to liquid oxygenates with high productivity and selectivity under mild reaction conditions is highly urgent but remains challenging. Herein, a Cu W codoped TiO2 (Cu–W–TiO2) photocatalyst was fabricated enable aerobic oxidation of into limited formation CO2 ambient temperature. A oxygenate 34.5 mmol g–1 remarkable 97.1% achieved over the Cu–W–TiO2 photocatalyst. Based on structural characterizations mechanism studies, it suggested that species acted as...

Selective oxidation of methane to oxygenates with O2 under mild conditions remains a great challenge. Here we report ZSM-5 (Z-5) supported PdCu bimetallic catalyst (PdCu/Z-5) for conversion by reacting in the presence H2 at low temperature (120 °C). Benefiting from co-existence PdO nanoparticles and Cu single atoms via tandem catalysis, PdCu/Z-5 exhibited high yield 1178 mmol g-1Pd h-1 (mmol per gram Pd hour) same time selectivity up 95 %. Control experiments mechanistic studies revealed...

The development of chiral ligands to fine-tune the stereocontrol has been recognized as a crucial pillar asymmetric catalysis. In contrast well-developed pyridine–pyridine-type and pyridine–oxazoline-type ligands, oxazole–pyridine-type have rarely exploited. this study, class [2.2]paracyclophane-based planar-chiral oxazole–pyridine N,N-ligands designed synthesized. These presented superior performance in enantioselective palladium-catalyzed acetoxylative cyclization alkyne-tethered...

Nerve growth factor (NGF) induces the rapid but transient expression of two transcripts with homology to proto-oncogene c-jun (AP-1) in PC12 cells. The increase within 15 min after NGF addition, peak at 1 h, and decline basal level by 4 h. Actinomycin D inhibits increase, cycloheximide prevents decrease mRNA. Cyclic AMP a similar rise human melanoma cell line A875 that also expresses receptor RNA constitutively, is not affected significantly NGF. does alter transcription SP-1 results suggest...

A streamlined method for the enantioselective synthesis of 2-amino-4H-chromenes from readily available 2-alkyl-substituted phenols and active methylene compounds bearing a cyano group with up to 97% ee is presented. This reaction cascade procedure including manganese dioxide mediated C–H oxidation generation o-quinone methides bifunctional squaramide-catalyzed Michael addition/cyclization.

A chiral phosphoric acid catalyzed asymmetric transfer hydrogenation of aromatic amines, quinolin-3-amines, was successfully developed with up to 99% ee. To supplement our previous work on the Ir-catalyzed 2-alkyl substituted a number 2-aryl substrates were reduced provide series valuable exocyclic amines high diastereo- and enantioselectivities.

Rhodium(III)- and iridium(III)-catalyzed C-H activation of oximes coupling with propargyl alcohols is discussed. Depending on the catalyst, reaction pathway switched between [3 + 2] [4 annulations, thus giving divergent access to indenamines isoquinolines in a one-pot atom-economical manner. The hydroxyl group tertiary alcohol substrate was found be crucial controlling chemoselectivity. Five-membered rhodacycle iridacycle intermediates have also been identified for mechanism hypotheses.

A highly enantioselective synthesis of chiral fluorinated propargylamines was developed through phosphoric acid and ruthenium-catalyzed chemoselective biomimetic hydrogenation the carbon-nitrogen double bond alkynyl ketimines in presence a carbon-carbon triple bond. This reaction features high chemoselectivity slow background reaction. In addition, selective transformations were also reported.

A highly enantioselective palladium-catalyzed hydrogenation of a series linear and cyclic α-iminophosphonates has been achieved, providing efficient access to optically active α-aminophosphonates with up 99% ee.

Highly selective conversion of methane to oxygenates with O2 as a green oxidant remains great challenge. It is still difficult suppress the generation COx (x=1, 2) undesired by-products due unavoidable overoxidation reaction. Hence, tungsten-doped (W-doped) TiO2 photocatalysts were designed tunable band structure for photocatalytic oxidation C1 using at low temperature (30 °C). The W-doping effectively modified electronic and pristine enhance performance. Liquid productivity could reach high...

Abstract A facile method for the stereoselective synthesis of trans ‐2,3‐dihydrobenzofurans from ortho ‐quinone methides in situ generated readily available 2‐alkyl‐substituted phenols using silver oxide‐mediated oxidation has been developed. Additionally, 2,3‐dihydrobenzofurans can be further transformed into aromatized 2,3‐disubstituted benzofurans presence DDQ. magnified image

Abstract An efficient, mild and redox‐neutral iridium(III)‐catalyzed C−H annulation of N ‐phenoxyacetamides for the regioselective synthesis benzofurans has been developed by employing tertiary propargyl alcohols as versatile coupling partners. The computed results together with experimental data revealed that hydroxyl group acts key factor in controlling regioselectivity tuning reactivity. magnified image

Cu single atoms embedded in the C3N4 (Cu-SAs/C3N4) matrix exhibited high activity with 95% oxygenate selectivity for direct conversion of methane at ambient temperature. The presence abundant anchoring sites led to highly dispersed Cu-N4 moieties, which were suggested be underlying active conversion.

A facile method has been developed for the synthesis of chiral piperazines through Ir-catalyzed hydrogenation pyrazines activated by alkyl halides, giving a wide range including 3-substituted as well 2,3- and 3,5-disubstituted ones with up to 96% ee. The high enantioselectivity, easy scalability, concise drug demonstrate practical utility.