Total Synthesis of α-Elvucitabine

Total synthesis of α-elvucitabine was achieved in 26% overall yield by a concise nine-step procedure starting from L-lyxose, with trimethylsilyl trifluoromethaneoulfonate (TMSOTf)–mediated stereocontrolled α-N-glycosidation and olefination through Barton–McCombie deoxygenation being the key steps, and the stereochemistry of the product was determined by nuclear Overhauser effect spectroscopy.     

Syngas production from methane over CeO2-Fe2O3 mixed oxides using a chemical-looping method

A series of mixed oxides Ce_{1 ? x} Fe _x O₂ was prepared by a hydrothermal method. XRD and Raman spectra were measured to study the structure of the prepared materials. The temperature-programmed reduction was undertaken to estimate reducibility of the oxides. Syngas generation from methane using these materials as oxygen carriers/catalysts via a chemical-looping procedure was investigated in detail. This procedure includes catalytic oxidation and decomposition of methane to produce H₂-rich gas at the first step followed by the production of the CO-rich gas by oxidizing the carbon deposited on deactivated catalysts. The results showed that all iron ions were incorporated into the ceria lattice with the formation of oxygen vacancies in the Ce_0.9Fe_0.1O₂ sample, while isolated Fe₂O₃ particles were distributed on the surface of the Ce_0.8Fe_0.2O₂ sample. TPR measurements and the analysis of the two-step chemical-looping reactions indicated a strong interaction between the Ce and Fe species which accounts for an increased activity of the mixed oxides in the syngas generation compared to that of individual oxides. Among the several samples, the Ce_0.8Fe_0.2O₂ catalyst showed the highest activity for methane partial oxidation due to the synergetic effects caused by the interaction of surface iron entities and Ce-Fe solid solution. In addition, selective oxidation of carbon by oxygen to CO can also be found over this material since gaseous products are formed at the carbon oxidation step with the selectivity to CO reaching 91.2%. Evidence is presented that syngas can be feasibly produced from methane with high selectivity via the chemical-looping procedure over the CeO₂-Fe₂O₃ mixed oxides.     

Prins Cyclization of Styrenes or Acetophenone Catalyzed by DBSA in Water

Dodecylbenzenesulfonic acid (DBSA) was proved to be an efficient catalyst for Prins cyclization of styrenes and formaldehyde or acetaldehyde in water. A tandem dehydration/Prins cyclization reaction using a tertiary alcohol and formaldehyde as substrates proceeded very well by using DBSA as catalyst. Acetophenone, which is less reactive compared with styrene, can also react with formaldehyde when catalyzed by DBSA in water to afford 1,3-dioxan-5-ylphenylmethanone in good yield.     

The State of NaOH in NaOH/Poly(Sodium Acrylate) Composite

NaOH/poly(sodium acrylate) composites were prepared by in situ polymerization of acrylic acid with an overneutralization level by adding excess NaOH. The composites were studied by XRD, IR and ²³Na MAS NMR spectroscopy. The results showed that the high neutralization degree (>100%) may lead to a complete polymerization. Both XRD and ²³Na MAS NMR spectra did not show any peaks of phase-separated NaOH or Na₂CO₃ until the neutralization degree was up to 217.5%. It can be presumed that the aggregates of Na⁺ ions can contain approximately two Na⁺ units for every carboxyl group before the phase separation.     

Copper‐Based Ternary and Quaternary Semiconductor Nanoplates: Templated Synthesis,Characterization, and Photoelectrochemical Properties

Two‐dimensional (2D) copper‐based ternary and quaternary semiconductors are promising building blocks for the construction of efficient solution‐processed photovoltaic devices at low cost. However, the facile synthesis of such 2D nanoplates with well‐defined shape and uniform size remains a challenge. Reported herein is a universal template‐mediated method for preparing copper‐based ternary and quaternary chalcogenide nanoplates, that is, CuInS₂, CuIn_xGa_1−xS₂, and Cu₂ZnSnS₄, by using a pre‐synthesized CuS nanoplate as the starting template. The various synthesized nanoplates are monophasic with uniform thickness and lateral size. As a proof of concept, the Cu₂ZnSnS₄ nanoplates were immobilized on a Mo/glass substrate and used as semiconductor photoelectrode, thus showing stable photoelectrochemical response. The method is general and provides future opportunities for fabrication of cost‐effective photovoltaic devices based on 2D semiconductors.     

One-pot reaction for the concise synthesis of spiro[benzofuran-2,2′-naphthalen]-1′-one derivatives

A novel one-pot two-step protocol has been developed to synthesize various spiro[benzofuran-2,2′-naphthalen]-1′-one derivatives from the three-component reaction of tetralones, 2-hydroxyphenyl functionalized α,β-unsaturated ketones, and iodine. One C–C bond and one C–O bond have formed during this process. The notable features of this protocol are simple and mild reaction conditions, applicable to a wide range of readily available starting materials, good yields (up to 91%), and excellent stereoselectivities (up to 97:3).     

Synthesis and Characterization of Ag8(Ge1−x,Snx)(S6−y,Sey) Colloidal Nanocrystals

A facile colloidal approach to synthesize Ag₈(Ge_1?x,Sn_x)(S_6?y,Se_y) nanocrystals (NCs) in a highly controlled way across the entire compositional ranges (0≤x≤1, 0≤y≤6) has been developed. The NCs exhibit a uniform size distribution, highly crystalline structure, over 1 g scalable synthesis, and tunable band gaps in the range of 0.88–1.45 eV by varying their chemical compositions. The Ag₈GeS₆ NCs with a band gap of approximately 1.45 eV were employed as a model light harvester to assess their applicability in solar cells by a full solution‐processing device, yielding an efficiency of 0.28 % under AM1.5 illumination, demonstrating their application potential in solar energy utilization.     

Light-Induced Chiral Iron Copper Selenide Nanoparticles Prevent β-Amyloidopathy In Vivo

The accumulation and deposition of β-amyloid (Aβ) plaques in the brain is considered a potential pathogenic mechanism underlying Alzheimer's disease (AD). Chiral l/d -Fe_xCu_ySe nanoparticles (NPs) were fabricated that interfer with the self-assembly of Aβ42 monomers and trigger the Aβ42 fibrils in dense structures to become looser monomers under 808 nm near-infrared (NIR) illumination. d -Fe_xCu_ySe NPs have a much higher affinity for Aβ42 fibrils than l -Fe_xCu_ySe NPs and chiral Cu_2−xSe NPs. The chiral Fe_xCu_ySe NPs also generate more reactive oxygen species (ROS) than chiral Cu_2−xSe NPs under NIR-light irradiation. In living MN9D cells, d -NPs attenuate the adhesion of Aβ42 to membranes and neuron loss after NIR treatment within 10 min without the photothermal effect. In-vivo experiments showed that d -Fe_xCu_ySe NPs provide an efficient protection against neuronal damage induced by the deposition of Aβ42 and alleviate symptoms in a mouse model of AD, leading to the recovery of cognitive competence.     

Bioorthogonal Ligation and Cleavage by Reactions of Chloroquinoxalines with ortho-Dithiophenols

A bioorthogonal ligation and cleavage method via reactions of chloroquinoxalines (CQ) and ortho-dithiophenols (DT) is presented. Double nucleophilic substitutions of ortho-dithiophenols to chloroquinoxalines provide conjugates containing tetracyclic benzo[5,6][1,4]dithiino[2,3-b]quinoxaline with strong built-in fluorescence together with release of the other functional molecules. Three cleavable linkers were designed and successfully used in release of the molecules containing biotin from the protein conjugates. The CQ-DT bioorthogonal reactions can be applied for the bioorthogonal ligations, bioorthogonal cleavages, and trans-tagging of proteins, and show advantages of readily accessible unnatural orthogonal groups, appealing reaction kinetics (k₂≈1.3 m ⁻¹ s⁻¹), excellent biocompatibility of orthogonal groups, and high stability of conjugates. This complements previous bioorthogonal reactions and is a new route for protein-fishing applications and in-gel fluorescence analysis.     

Palladium‐Catalyzed Asymmetric [4+3]‐Cyclization Reaction of Fused 1‐Azadienes with Amino‐trimethylenemethanes: Highly Stereoselective Construction of Chiral Fused Azepines

Summary of main observation and conclusion A Pd-catalyzed asymmetric aromative[4+3]-cyclization reaction of amino-trimethylenemethanes(TMM,1d,ip3-oles)with fused 1-azadienes has been developed.This method enables access to the synthetically importance and biologically active benzofuran fused azepines and indeno-azepines in excellent efficiency and stereoselectivity(up to 95%yield,99%ee,>19:1 dr).