Syntheses of 2- or 6-Substituted Chromones and Chromone Ring-opening Reaction in Polyphosphoric Acid

In an attempt to find new antitumor agents,a novel class of chromone compounds with a benzimidazole or a benzoxazole ring in positions 2 or 6 were synthesized via condensation in polyphosphoric acid(PPA) by using chromone acids as the starting materials. During the preparation process,it was found that PPA could cleave the chromone ring to produce a ring-opening compound(6). The molar ratio of the chromone compound(5) to the ring-opening compound(6) varied with the change of reaction temperature and time. Based on MTT protocol,the antitumor activity of each of the compounds obtained was evaluated against three human cancer cell lines: KB(oral epidermal),A2780(ovary) and Bel7402(liver). The IC_ 50 varied from 54.7 μmol/L to more than 180 μmol/L.

Carbene-Catalyzed Asymmetric Ring-Opening Reaction of Biaryl Lactams to Access Axially Chiral Biaryls

Axially chiral biaryls represent the most important class of atropisomers,and they widely exist in natural products and biologically active molecules.They also constitute a unique scaffold for chiral ligands and catalysts in organic synthesis.The development of synthetic methods to obtain such chiral compounds has received widespread attention,among which catalytically atroposelective ring-opening of configurationally labile compounds represents one of the most attractive strategies.Various substrates with strained cyclic structures,such as the renowned Bringmann's lactones,can undergo asymmetric transformation into stable atropisomers.Known advancement primarily relies on metal catalyst combined with well-designed chiral ligands,the approaches utilizing organocatalysis as a critical resolution strategy are notably scarce.In this study,we disclosed a N-heterocyclic carbene(NHC)-catalyzed asymmetric ring-opening reaction of biaryl lactams via direct atroposelective nucleophilic activation.The optimized bulky carbene catalyst ensures that the reaction can proceed under mild conditions,affording the desired product with good to excellent yields and atroposelectivity.

Preparation of nucleoside-pyridine hybrids and pyridine attached acylureas from an unexpected uracil ring-opening and pyridine ring-forming sequence

Novel pyrimidine nucleoside-3,5-dicyanopyridine hybrids （4） or pyridine attached acylureas （5） were selectively and efficiently prepared from the reaction of 2′-deoxyuddin-5-yl-methylene malononitrile （1）, malononitrile （2） and thiophenol （3） or from an unexpected uracil ring-opening and pyddine ring-forming sequence via the reaction of 1 and 3. It is the first time such a sequence has ever been reported.

TARTARIC ACID TEMPLATED SYNTHESIS OF MESOPOROUS Ti-INCORPORATED SILICA AND ITS CATALYTIC ACTIVITY FOR THE RING-OPENING POLYMERIZATION OF ε-CAPROLACTONE

Ti-incorporated mesoporous silica materials with pore diameters of 3-4 nm have been prepared via the co-hydrolysis and co-condensation reactions, that is the sol-gel reactions, of titanium (IV) tetrabutoxide and tetraethylorthosilicate in the presence of tartaric acid as template, followed by extraction with ethanol to remove the templatemolecules. The materials were characterized in detail by Fourier transform infrared spectroscopy, nitrogen adsorption-desorption test, powder X-ray diffraction, transmission electron microscopy and X-ray energy dispersive spectroscopy. Theresults indicate that the Ti-containing silica materials have large specific surface areas (ca. 1200 m^2 g^(-1)) and pore volumes(ca. 0.900 cm^3 g^(-1)). The mesoporosity arises from disordered interconnecting channels or pores. The Ti-incorporated silicasexhibit catalytic activity for the ring-opening polymerization of ε-caprolactone, otherwise, the pure mesoporous silicamaterial shows no catalytic activity under the identical conditions.

Pd(I)-catalyzed ring-opening arylation of cyclopropyl-α-aminoamides:Access toα-ketoamide peptidomimetics

We report the unprecedent Pd(I)catalyzed ring-opening arylation of cyclopropyl-α-aminoamides.This protocol allows facile access to biologically important α-ketoamide-containing oligopeptides and even more challenging peptide-natural product conjugates.Site selectivity was achieved by introduction of special unnatural amino acids,which also meets the requisite of bioorthogonal chemistry.Mechanism investigations reveals a distinct domino radical ring-opening process through Pd(I)catalysis.

Epoxidation of Styrene-Isoprene-Styrene Block Copolymer and Research on Its Reaction Mechanism

Styrene-isoprene-styrene（SIS） block copolymer was modified into epoxidized styrene-isoprene-styrene（ESIS） block copolymer with performic acid generated in situ from hydrogen peroxide and formic acid.The structure and property of ESIS were characterized by Fourier transform infrared（FT-IR） spectroscopy,gel permeation chromatography（GPC）,thermogravimetric/differential thermogravimetric（TG/DTG）,melt flow rate（MFR） and dynamic mechanical analysis（DMA）,and the reaction mechanism in the process of epoxidation was analyzed.The results showed that C=C double bonds of 1,4-structure were more active than that of 3,4-structure in polyisoprene chains.With epoxidation reaction proceeding,the whole tendency of molecular weight increased and molecular weight distribution widened,and MFR firstly increased and latterly decreased.The heat resistance of ESIS was superior to that of SIS.When SIS was changed into ESIS with 15.3% of mass fraction of epoxide groups,Tg of polyisoprene chains increased from-45.3 ℃ to 10.9 ℃.In the earlier period of epoxidation,some molecular chains ruptured and new substances with low molecular weight formed.However,in the latter period,crosslinking reaction between molecular chains which was initiated by epoxide groups or C=C double bonds occurred and crosslinked insoluble substances came into being.

Polymerization of Dicyclopentadiene by Reaction Injection Molding

Dicyclopentadiene was polymerized by reaction injection molding (RIM) using a catalyst system based on molybdenum (V) chloride and anhydrous aluminum chloride and triethylaluminum. The effect of the reaction temperature on the polymer network and the type of the polymerization were discussed.

Facile access to β-hydroxyl ketones via a cobalt-catalyzed ring-opening/hydroxylation cascade of cyclopropanols

A cobalt-catalyzed ring-opening/hydroxylation cascade of highly strained cyclopropanols has been developed for the first time. The reaction was conducted under open-air atmosphere to afford a broad series of structurally diverse β-hydroxy ketones in moderate to good yields with high regioselectivity.The protocol features mild reaction conditions, simple operation, high-functional-group tolerance, facile scalability, and heterocycle compatibility.

Uniform Metal Sulfide@N-doped Carbon Nanospheres for Sodium Storage: Universal Synthesis Strategy and Superior Performance

Nitrogen-doped carbon-coated transition-metal sulfides(TMS@NCs)have been considered as efficient anodes for sodium-ion batteries.However,the uncontrollable morphology and weak core-shell binding forces significantly limit the sodium storage performance and life.Herein,based on the reversible ring-opening reaction of the epoxy group of the tertiary amino group-rich epoxide cationic polyacrylamide(ECP)at the beginning of hydrothermal process(acidic environment)and the irreversible ring-opening(cross-linking reactions)at the late hydrothermal period(alkaline environment),47 nm-sized ZnS@NCs were prepared via a one-pot hydrothermal process.During this process,the covalent bonds formed between the ZnS core and elastic carbon shell significantly improved the mechanical and chemical stabilities of ZnS@NC.Benefiting from the nanosize,fast ion/electron transfer,and high stability,ZnS@NC exhibited a high reversible capacity of 421.9 mAh g^(−1) at a current density of 0.1 A g^(−1) after 1000 cycles and a superior rate capability of 273.8 mAh g^(−1) at a current density of 5 A g^(−1).Moreover,via this universal synthesis strategy,a series of TMS@NCs,such as MoS_(2)@NC,NiS@NC,and CuS@NC were developed with excellent capacity and cyclability.

Tracking the Process of Domino Ring-Opening and Coupling of Fused Imidazole and Direct Observation of Peroxide Intermediates

Comprehensive Summary,A domino ring-opening and coupling of imidazolyl annulated heterocycles 1(1a:4-methyl-1-(1-methyl-1H-benzo[d]imidazol-2-yl)-4H-benzo[d]imidazo[1,5-a]imidazole,1b:1-(1,5-dimethyl-1H-benzo[d]imidazol-2-yl)-4,7-dimethyl-4H-benzo[d]imidazo[1,5-a]imidazole)with dioxygen was developed at solvothermal condition,leading to conjugated 1,2-diamidoalkenes derivatives 2((E)-ArCONHArC=CArNHCOAr(Ar:1-methyl-1H-benzo[d]imidazolyl(2a),1,5-dimethyl-1H-benzo[d]imidazolyl(2b)))as single crystals directly.The reaction process was tracked by electrospray ionization mass spectrometry(ESI-HRMS)and a series of reaction intermediates are detected.^(18)O_(2) labeling experiment verified the source of oxygen in 2.Combining evidence from control experiments,nuclear magnetic resonance(NMR)tracking,and crystallography,a seven-step reaction pathway involving oxygen addition,ring opening,Friedel-Crafts alkylation,oxidation,and dehydration was proposed and further supported by DFT calculation.

Platinum-Catalyzed Asymmetric Ring-opening Reaction of Oxabenzonorbornadiene with Terminal Alkynes

A novel platinum-catalyzed asymmetric ring-opening reaction of oxabenzonorbornadiene with terminal alkynes is described.The reaction affords optically active cis-2-alkynyl-1,2-dihydronaphthalen-1-ols in moderate yields with good enantioselectivity in the presence of catalytic amounts of Pt(COD)Cl_(2)/(S)-BINAP and an excess of zinc powder.The products were obtained exclusively with the relative cis-configuration of the ring substituents and the prevalent(1R,2S)-configuration of the stereocenters,as determined by single crystal X-ray diffraction analysis.

A semiclassical molecular dynamics of the photochromic ring-opening reaction of spiropyran

The photochromic ring-opening reaction of spiropyran（SP） has been investigated by a realistic semiclassical dynamics simulation,accompanied by SA3-CASSCF（12 10）/MS-CASPT2 potential energy curves（PECs） of S0–S2.The main simulation results show the dominate pathway corresponds to the ringopening process of trans-SP to form the most stable merocyanine（MC） product.These findings provide more important complementarity for interpreting experimental observations.

Functionalized Polyphosphoester via Living Ring-opening Polymerization and Photochemical Thiol-ene Click Reaction

Poly(ethylene phosphonate)was synthesized via the living ring-opening polymerization of cyclic phos-phonate monomer catalyzed by organocatalyst.The pendant vinyl ftmctionalities were employed to perform the pho-tochemical click reactions wi&tMols.We demonstrated that both small thiol molecules and macromolecular thiols could be efficiently coupled into the PPE side chains,enabling the rapid and efficient functionalization of polyphos-phoesters(PPE).

A novel four-component reaction involving ring-opening/recyclization of 1,3-thiazolidinedione

The multicomponent reactions of 1,3-thiazolidinedione, malononitrile, aromatic aldehydes and α-phenylethylamine or β-phenylethylamine in acetonitrile at room temperature produce dihydrothiophene ureidoformamide derivatives in moderate yields through a domino ring-opening/recyclization reaction of 1,3-thiazolidinedione. On treatment with DDQ, dihydrothiophenes are dehydrogenated to convert efficiently to thiophenes in the mild condition.

The reduction ring-opening reaction of imidazoline

A new reduction ring-opening reaction of 2-imidazoline with sodium borohydride is reported, and the effect of reaction condition on the yield, reaction mechanism and the use of the new reaction in synthesis of ethylenediamine derivatives are discussed. A new method for the preparation of unsymmetrical substituted ethylenediamine via the reduction ring-opening reaction of imidazoline is provided.

Cationic Micelle-catalyzed Ring-Opening Reactions of Aziridines with Thiols in Water

An efficient and practical method is described for the ring-opening reactions of N-tosylaziridines with various thiols in water under mild conditions. Various surfactants have been evaluated to optimize the reactions. Under optimal conditions, these reactions gave rise to the corresponding β-amino sulfides in good to excellent yields.

真空下钢液脱氮工艺研究

在４０ｋｇ真空感应炉上进行了真空下钢液脱氮工艺的实验研究。实验考察了真空下碳氧反应工艺、表面活性元素控制和脱氮渣系等因素对钢液脱氮动力学的影响。研究结果表明：（１）真空下强烈的碳氧反应能有效地脱除钢中的氮；（２）当钢中硫含量较低时，脱氮速率很快，随着硫含量的逐步增加，脱氮速率相应降低；（３）５０％ＳｉＯ２－４０％Ｂ２Ｏ３－１０％ＴｉＯ２渣系有明显的脱氮效果。

选择性非催化还原(SNCR)技术及其应用前景

介绍了SNCR工艺原理及反应机理,详细讨论了反应温度、NH3/NOx摩尔比、不同还原剂、不同添加剂以及烟气中氧对SNCR反应过程和脱硝效率的影响。展望SNCR技术的发展方向,介绍了SNCR与其他脱硝技术的联合应用。

润滑油基础油的溶剂脱氮技术

为了提高润滑油的氧化安定性，用络合萃取的方法对减二线和减三线脱蜡油进行了脱氮精制处理实验。结果表明，苯甲醇与金属盐的混合溶剂能够有效地脱除脱蜡油中的碱性氮化合物，其脱氮率能达９０％以上，而硫化物的脱除率很低，并且油品的质量也有所提高，在白土精制过程中可适当减少白土用量。

脉冲放电等离子体烟气脱硫脱硝工业试验

40000—50000Nm^3／h工业试验结果表明：烟气温度75℃-80℃，脱硫效率大于90％，脱硝效率大于40％，烟气温度90℃-95℃，脱硫效率大于80％，脱硝效率大于50％；能耗小于3.0Wh／Nm^2；随着温度升高，SO2热化学反应效率逐渐降低；随着氨硫化学计量比增大，氨泄漏逐渐增加，烟气温度90℃。95％，氨泄漏增加更为迅速。并分析了副产物的成分，阐述了脱硫脱硝的机理，探讨了烟气排放的温度。