High tension cyclic hydrocarbons synthesized from biomass-derived platform molecules for aviation fuels in two steps

Synthesizing ring structure aviation fuels from biomass-derived platform molecules is challenging,especially for bridged ring structure aviation fuels which are typically achieved from fossil-derived chemicals.Herein,we report the synthesis of a series of ring structure biofuels in two steps by a combination of a solvent-free Michael-cyclization reaction and a hydrodeoxygenation(HDO)reaction from lignocellulosederived 5,5-dimethyl-1,3-cyclohexanedione.These biofuels are obtained with high overall yields up to 90%,which exhibit high densities of 0.81 g cm^(-3)-0.88 g cm^(-3)and high volumetric neat heat of combustion(VNHOC)values of 36.0 MJ L^(-1)-38.6 MJ L^(-1).More importantly,bridged-ring structure hydrocarbons can also be achieved in two steps by a combination of a Robinson annulation reaction and an HDO reaction to afford the final products at high overall yields up to 90%.The bridged-ring structure products have comparable high densities and high VNHOC values to the best artificial fuel JP-10(0.94 g cm^(-3)and 39.6 MJ L^(-1)).The results demonstrate a promising way for the synthesis of high-density aviation fuels with different fuel properties at high yields.

当代数学和数学教育的若干趋势

当代数学和数学教育的若干趋势张奠宙（华东师范大学数学系，上海２０００６２）当代数学正在一日千里地向前发展。至于常常听说的所谓＂第三次数学危机＂，那是哲学家们在故作惊人之语。数学并没有陷入危机，只不过面临某些困难而已。数学的自身调整能力，会使数学科学更...

Synthesis,Crystal Structure and Antibacterial Activities of 4-Methyl-2-(4-methylphenyl)-5-(2-thiazolinyl)-1,3-thiazole

4-Methyl-2-（4-methylphenyl）-5-（2-thiazolinyl）-1,3-thiazole, a novel compound, was synthesized by the annulation of 5-hydroxyethylcarbamoyl-4-methyl-2-（4- methylphenyl）-1,3-thiazole with P2S5. 5-Hydroxyethylcarbamoyl-4-methyl-2-（4-methylphenyl）-1,3-thiazole was prepared from the starting material of p-tolunitrile. The newly synthesized compounds were characterized by elemental analysis, IR, NMR（^1H, ^13C） and MS spectra. Hence, the crystal of the title compound was obtained, and its structure was determined by X-ray diffraction analysis. The crystal belongs to the triclinic system, space group P1 with a = 7.354（4）, b = 8.383（4）, c = 11.543（6）A, α = 76.688（6）, β = 72.299（6）, γ = 88.157（6）°, V = 659.2（6） A^3, Z = 2, Mr = 274.39, Dc = 1.382 g/cm^3, μ = 0.386 mm^-1, F（000） = 288, R = 0.0586 and w R = 0.1808 for 2984 unique reflections with 2213 observed ones（I 〉 2σ（I））. The title compound was also screened for its antibacterial activities against Bacillus subtilis and Escherichia coli. The result indicates that the target compound presents potential antimicrobial activities, and that the minimum inhibitory concentration（MIC） values of the title compound against the two tested strains are both 62.5 μg/mL.

A Convergent Route for the Synthesis of AF-5

AF-5 was synthesized through a convergent method. The key step was the Robinson annulation using a key intermediate pentyl vinyl ketone.

Further Developments on the Regioselective Synthesis of 3-Aroylindole Derivatives from C-Nitrosoaromatics and Alkynones: A Novel Synthetic Approach to Pravadoline, JWH-073, Indothiazinone Analogues and Related Compounds

An uncatalyzed and easily accessible synthetic approach for the preparation of 3-aroylindoles was investigated using nitrosoarenes and aromatic terminal ethynyl ketones. Indole derivatives were produced in good yields and excellent regioselectivity. Functionalizations of the indole products were carried out affording highly valuable and versatile compounds. The indolization protocol was studied as a fundamental step for the preparation of pravadoline and 1-butyl-3-(1-naphthoyl)indole (JWH-073), bioactive molecules showing antinociceptic properties.

Visible Light-Induced[3+2]Annulation Reaction of Alkenes with Vinyl Azides:Direct Synthesis of Functionalized Pyrroles

A photocatalytic[3+2]annulation of alkenes with vinyl azides was developed under irradiation by visible light in the presence of organic dye photocatalysts.Broad substrate scope and high functional group tolerance were demonstrated by more than 50 examples.The reaction provides a novel and efficient method for the synthesis of polyfunctionalized pyrroles under very mild metal-free conditions without other additives.

Metal-Free Photocatalytic[4+2]Annulation of Acrylamides with 2-Benzyl-2-bromocarbonyls to Assemble Tetralin-1-carboxamides

Tetralin-1-carboxamides are frequently incorporated in myriad medicinally important molecules.However,their existing synthetic routes not only suffer from some drawbacks such as tedious procedures,harsh reaction conditions,narrow substrate scope,low yields,and environmental problems,but are also based upon the elaboration of uneasily available non-linear tetralin derivatives.Herein,we describe a metal-and additive-free visible light-induced[4+2]annulation of two simple linear starting materials,namely acrylamides and 2-benzyl-2-bromocarbonyls,through a cascade C(sp^(3))-Br/C(sp^(2))-H bond cleavage,double C-C bond formation,and aromatization sequence.The developed protocol provides a convenient,efficient,and green approach to a variety of tetralin-1-carboxamide derivatives with good functional group compatibility.Importantly,the resulting products could also undergo the Licl-mediated mono-decarboxylative cyclization process to further furnish the architecturally novel bridged polycyclic imides with excellentcis-diastereoselectivities.

An Assembly of Pyrano[3,2-b]indol-2-ones via NHC-Catalyzed[3+3]Annulation of Indolin-3-ones with Ynals

We report herein an unprecedented N-heterocyclic carbene-catalyzed formal[3+3]annulation of ynals with N-Ts indolin-3-ones under the oxidation condition affording the functionalized pyrano[3,2-b]indol-2-ones.The alkynyl acylazoliums via the combination of a carbene with ynals in the presence of oxidate proved to be the important intermediates for the success of this transformation.This method features a broad substrate scope and mild conditions,including axially chiral skeletons with suitable substitutions.

Palladium-catalyzed stereoselective decarboxylative[4+2]cyclization of 2-methylidenetrimethylene carbonates with pyrrolidone-derived enones:Straightforward access to chiral tetrahydropyran-fused spiro-pyrrolidine-2,3-diones

A novel asymmetric[4+2]cycloaddition of 2-methylidenetrimethylene carbonate with pyrrolidonederived enones has been achieved to produce the functionalized tetrahydropyran-fused spirocyclic scaffolds via palladium-catalysis.An array of enantioenriched spiro-pyrrolidine-2,3-diones bearing adjacent quaternary and tertiary stereocenters are obtained in high yields with excellent enantioselectivities(up to 96% yield and 99% ee).The further transformation of the product has been accomplished for the construction of medical interesting β^(2,2)-amino acids and β-lactams.Preliminary mechanistic research was well conducted.

Phosphine-Catalyzed [4+3] Annulation Reaction of Indole Derivatives with MBH Carbonates:A Facile Access to Indole-1,2-fused 1,4-Diazepinones and Azepines

A phosphine-catalyzed [4+3] annulation between dinucleophilic indole derivatives and Morita−Baylis−Hillman (MBH) carbonates was discovered by using the N1 and N4′/C4′ nucleophilicities of the indole precursors,in which indoles act as four atom synthons. This protocol provides an efficient and facile access to indole-1,2-fused 1,4-diazepinones and azepines in good to high yields in one step,which illustrates potential synthetic utilities in drug discovery.

Synthesis of 9,10-Phenanthrenes via Rh(III)-Catalyzed[4+2]Annulation of 2-Biphenylboronic Acids with Diazo Compounds

A Rh(III)-catalyzed,transmetalation triggered C—H activation/annulation of 2-biphenylboronic acids with diazo compounds fromβ-keto esters or 1,3-dicarboxylates has been developed,leading to the synthesis of two kinds of 9,10-phenanthrenes.Notably,a rhodacyle was synthesized by treating the rhodium catalyst with stoichiometric amounts of 2-biphenylboronic acids and pyridine,which was further verified to be active for the catalytic system.The reactions proceeded under redox-neutral and air-tolerant conditions to produce a series of all-carbon six-membered rings with high efficiency.

Catalyst-Free Regio-and Diastereoselective Synthesis of Heterocyclic Nucleosides in the Eco-friendly Solvent 2-Methyltetrahydrofurant

An efficient and practical synthesis of heterocyclic nucleosides is developed by a catalyst-free highly regioselective and diastereose-lective[3+2]annulation of a-purine-substituted acrylates with nitrones.The reaction operates with excellent functional group toler-ance,very mild reaction conditions,and with the green,sustainable,and eco-friendly 2-methyltetrahydrofuran(2-MeTHF)as sol-vent.Compared with other reactions of electron-deficient olefin dipolarophiles with nitrones,different regioselective cycloaddition products were observed in this work.This 1,3-dipolar cycloaddition reaction gives a series of isoxazolidinyl nucleosides in good to excellent yields with promising applications in biochemistry and medicinal chemistry.

Palladium-catalyzed annulative allylic alkylation for regioselective construction of indole-fused medium-sized cyclic etherS

A new palladium-catalyzed annulative allylic alkylation(AAA)reaction of 2-(indol-2-yl)phenols with dual allylic electrophiles such as isobutylene dicarbonate and butene dicarbonate is described,leading to the regioselective synthesis of tetracyclic medium-sized cyclic ethers possessing a bridged aryl-indole scaf-fold,namely,benzo[2,3]oxocino[4,5-b]indoles and benzo[2,3]oxepino[4,5-b]indoles,in good to excellent yields.This protocol demonstrates a broad substrate scope,good compatibility with substituents and high regioselectivity,providing a catalytic and flexible method for creating bridged aryl-indole skeletons.

Derivation of Benzothiadiazine-1,1-dioxide Scaffolds via Transition Metal-Catalyzed C-H Activation/Annulation

Comprehensive Summary Benzothiadiazine-1,1-dioxide scaffold is bioactive framework with wild utility and applications.Synthesis of benzothiadiazine-fused isoquinoline derivatives and spiro benzothiadiazine derivatives through transition metal-catalyzed C—H activation/annulation was reported.3-Phenyl-2H-benzothiadiazine-1,1-dioxide was used as the reaction substrate,and vinylene carbonate and 4-diazopyrazolone were used as the coupling reagents,respectively.This strategy provides straightforward access to complex N-heterocycles in a highly efficient and simple manner.

Diverse catalytic systems for nitrogen-heterocycle formation from O-acyl ketoximes

O-Acyl ketoximes has been proven to be versatile building blocks for practical construction of Nheterocycles.In the last few years,diverse catalytic systems have been discovered to enable efficient transformations of O-acyl ketoximes to a range of nitrogen-heterocycles.Herein,we summarized our recent examples of novel nitrogen-heterocycle formation with new function findings of O-acyl ketoximes through facile aerobic copper catalysis,metal-free N–O bond activation,multi-component assembly,and bis-annulations.From the green chemistry perspective,these works represent efficient methods with high atom economy,high selectivity,and minimized chemical waste.These findings also complement well to the previous mainly copper-based catalytic systems and more importantly enrich the oxime chemistry in organic synthesis.

Facile synthesis and functionalization of fluoranthenes via intramolecular[4+2]annulations between thiophenes and alkynes

Fluoranthenes have attracted tremendous attention due to their unique optoelectronic properties and extensive applications.Although several synthetic methodologies have been developed for the preparation of fluoranthene derivatives,it is still unfavorable to functionalize the fluoranthene framework at different positions due to the relatively low selectivity and reactivity.Herein,a catalyst-free intramolecular[4+2]annulation between thiophenes and alkynes is developed towards the synthesis of fluoranthenes.Altogether 20 examples have been demonstrated using this method.Various functional groups can be precisely introduced into the fluoranthene skeleton at different positions by simply tuning the substituents on the thiophenes and alkynes.The conjugation of the fluoranthene can be facilely extended through different directions.Furthermore,the feasibility of this[4+2]annulation reaction is also investigated by density functional theory calculations.Therefore,this protocol provides not only a synthetic methodology towards fluoranthenes with substituents functionalized at different positions,but also an effective pathway to construct large polycyclic aromatic hydrocarbons containing fluoranthene moieties.

Studies on reaction mechanisms and distinct chemiluminescence from cyanoimino neonicotinoids triggered by peroxymonosulfate in advanced oxidation processes

In this study, we proposed a novel method to investigate the advanced oxidation process of neonicotinoids(NNIs) from the perspective of concomitant chemiluminescence(CL) reaction. It was found that in the presence of cobalt ions with cyanoimino NNIs, acetamiprid(ACE) and thiacloprid(THI), could promote peroxymonosulfate and Ru(bpy)_(3)^(2+) to produce strong CL, but no CL occurred with nitro-involved NNIs as alternatives. Experimental dada from UV absorption spectra and chemiluminescence spectra suggested that new cyclic compounds might be formed during the reaction. Based on the results of free radical scavenging experiment and mass spectra, a new degradation and reaction mechanism of cyanoiminocontaining NNIs was proposed. ACE or THI were first attacked by SO_(4)^(·-) to form benzyl radicals, which in turn reacted with the carbon atoms of cyano group through electrophilic addition reaction in the formation of intramolecular ring. Then a redox reaction between Ru(bpy)_(3)^(3+) and imino group immediately took place with CL emission(610 nm). The new mechanistic knowledge would be meaningful for other contaminants for their interactions with PMS.

Solvent-dependence of KI Mediated Electrosynthesis of Imidazo[1,2-a]pyridines

Iodized salts are widely used as mediators to promote C-H functionalization.Solvents and additives have been described as significant roles in these reactions.However,the further electrochemical investigations have rarely been reported.Herein,a KI mediated electrochemical annulation between acetophenones and 2-amniopyridines was developed.We revealed the effect of acids and solvents by cyclic voltammetry(CV),differential pulse voltammetry(DPV),and square wave voltammetry(SWV).The oxidation of 2-aminopyridine is inhibited at the potential window with the addition of strong acids,and the lowest oxidation potential difference of KI was obtained by utilizing EtOH as solvent.The experimental studies also show that the mixture solvent of EtOH/DMSO(9/1,volume ratio)facilitates the electrochemical cyclization due to the solubility improvement of KI.CF3SO3H has been screened as the optimal acid.A range of Imidazo[1,2-a]-pyridines have been synthesized in yields of 42%to 96%.Electrochemical investigations present that the KI mediated electrochemical reaction is probably solvent-dependence.

π-Extension of Isoindigos(IIDs)through C—H/N—H Activation and Alkyne Annulation

Isoindigo(IID)is widely used as organic dye and conjugated unit in opto-electronic materials.Functionalization of IID to increase its structural complexity is demanding for obtaining diversity properties.Herein,we developed a direct C-H/N-H activation method of IIDs via double alkyne annulations and synthesizedπ-extended IIDs with two pairs of 5/7 membered rings.The structure of theπ-extended IIDs was characterized and confirmed by^(1)H NMR,^(13)C NMR,HRMS and X ray crystal analysis.Their physical properties were characterized by UV-vis absorption,cyclic voltammetry and thermogravimetric analysis.The absorption coefficient of the annulated products enhanced significantly compared with the non-annulated analogue.