Synthesis Features Research Articles

Total Synthesis of the Proposed Structure of Neaumycin B.

The total synthesis of the proposed structure of anti-glioblastoma natural product neaumycin B was achieved in 22 steps (longest linear sequence). The synthesis features HCl-mediated [6,6]-spiroketalization, a combination of Krische iridium-catalyzed crotylation, Marshall palladium-catalyzed propargylation, Fürstner nickel-catalyzed regio- and enantioselective vicinal monoprotected diol formation, Brown crotylation and asymmetric halide-aldehyde cycloaddition, so as to establish the challenging contiguous stereocenters.

Total Synthesis of the Proposed Structure of Neaumycin B

AbstractThe total synthesis of the proposed structure of anti‐glioblastoma natural product neaumycin B was achieved in 22 steps (longest linear sequence). The synthesis features HCl‐mediated [6,6]‐spiroketalization, a combination of Krische iridium‐catalyzed crotylation, Marshall palladium‐catalyzed propargylation, Fürstner nickel‐catalyzed regio‐ and enantioselective vicinal monoprotected diol formation, Brown crotylation and asymmetric halide‐aldehyde cycloaddition, so as to establish the challenging contiguous stereocenters.

Construction of Cyclobutane‐Centered Tricyclic Caged Skeleton through a [5,5]‐Rearrangement Triggered Cascade

AbstractIn this report, we describe the combination of [5,5]‐rearrangement‐triggered dearomatization recently developed in our laboratory with an intramolecular formal [2+2]‐cycloaddition for constructing an intriguing polysubstituted tricyclo[4.2.1.03,8]nonane derivatives. The synthesis features the use of simple and readily available three distinct starting materials including aryl sulfoxides, allyl nitriles, and certain nucleophiles or dienes which directly enriches the diversity of target molecules. This study provides an entirely new protocol for the synthesis of cyclobutane‐centered tricyclic caged skeleton.

Fluorescent and electronic properties of Dysprosium acylpyrazolone complexes along with their synthesis and structural features

Six distorted square antiprismatic eight coordinated Dysprosium acylpyrazolone complexes were synthesized having the compositions [Dy(L1)3(EtOH)(H2O)] (DyL1), [Dy(L2)3(EtOH)(H2O)] (DyL2), [Dy(L3)3(EtOH)(H2O)] (DyL3), [Dy(L4)3(EtOH)(H2O)] (DyL4), [Dy(L5)3(EtOH)(H2O)] (DyL5), and [Dy(L6)3(H2O)(EtOH)] (DyL6). The structure of all six complexes was examined using ESI-mass, FT-IR, UV–Vis, powder XRD, and thermogravimetric methods. According to the single crystal analysis of DyL4A, the complex was found eight coordinated (DyO8) with a distorted square antiprismatic geometry. The comparison of stimulated powder pattern of DyL4A crystal and experimental powder x-ray data helps to confirm the geometry of other complexes. In the solid-state emission spectra, the transition 4F9/2→6H13/2, which is close to the yellow region of the visible spectrum (∼510–530 nm), exhibits hypersensitivity. The variance in intensity between electric-dipole and magnetic-dipole transition suggests a less asymmetric environment. The solvent effect has been thoroughly investigated through a comparative analysis of electronic spectra in different solvents. The intensity of emission spectra, Y/B ratio, and antenna effect energy diagram were examined from solid-state emission spectra.

Construction of polyaniline coated FeMnCu co-doped Prussian blue analogue as cathode for sodium ion battery

Prussian blue crystal of sodium hexacyanoferrate is widely applied as the cathode for sodium ion battery (SIB) due to the features of high specific capacity and easy synthesis. While, the existed coordinated water and vacancy defects will cause the skeleton collapsed and lattice disordered during the cycling process, which lower the coulombic efficiency and shorten the cycle consistency. Furthermore, the inferior electron transport of Fe-HCF further affects the charge-discharge performance. Herein, we designed a high-quality FeMnCu co-doped Prussian blue (PB) crystal and controlled its crystallization process with assistance of citrate. Moreover, a core-shell structure of conductive polyaniline (PANI) coated Prussian blue analogue (FeMnCu@PANI) was constructed. The as-developed FeMnCu@PANI as the cathode for SIB delivers a capacity of 107 mAh g-1 at the current density of 1C and 82 mAh g-1 at 10C. The capacity retention rate reaches ∼90 % at 10C for 500 cycles. This FeMnCu@PANI crystal is nontoxic, high yield, low cost, and suitable for large-scale producing, which has great potential as cathode for SIB with high-capacity retention rate and long service life.

Phenomic and transcriptomic analyses reveal the sequential synthesis of Fe3O4 nanoparticles in Acidithiobacillus ferrooxidans BYM.

Understanding the molecular mechanism of magnetite (Fe3O4) nanoparticle synthesis in Acidithiobacillus ferrooxidans BYM is particularly important for the commercial development of biogenic Fe3O4 nanoparticles. The phenomic parameters such as intracellular iron content and number and size of Fe3O4 nanoparticles were significantly affected by different treatment conditions, i.e., FeSO4·7H2O concentrations (0, 40, and 80 g/L), growth times (12, 36, and 50 h), and magnetic field intensities (0.05, 3.5, and 15 mT) (P < 0.01). Transcriptome analysis revealed that 2,164, 1,587, and 1,061 differentially expressed genes (DEGs) were accordingly detected, and 24 significant expression profiles were identified in A. ferrooxidans BYM under the three treatment conditions. The construction of gene regulatory networks for Fe3O4 nanoparticle synthesis indicated that DEGs mainly enrich ion transport, oxidation-reduction process, membrane structure, signal transduction, and quorum sensing. The four modules were found to be significantly associated with Fe3O4 nanoparticle phenomic parameters using a weighted gene co-expression network. Ten hub genes significantly correlated with Fe3O4 nanoparticle phenomic parameters (P < 0.01) were finally selected from 24 eigengenes related to iron metabolism screened from these models. On the basis of the previous research results and the present study findings, we provide a hypothetical molecular model for Fe3O4 nanoparticle synthesis mediated by these hub genes in A. ferrooxidans BYM comprising membrane formation, iron uptake and transport, iron redox, and crystal maturity. Our results will enable in-depth studies of Fe3O4 nanoparticle synthesis in non-magnetotactic magnetosome-producing bacteria. IMPORTANCE As the most important non-magnetotactic magnetosome-producing bacteria, Acidithiobacillus ferrooxidans only requires very mild conditions to produce Fe3O4 nanoparticles, thus conferring greater flexibility and potential application in biomagnetic nanoparticle production. However, the available information cannot explain the mechanism of Fe3O4 nanoparticle formation in A. ferrooxidans. In this study, we applied phenomic and transcriptomic analyses to reveal this mechanism. We found that different treatment condition factors notably affect the phenomic data of Fe3O4 nanoparticle in A. ferrooxidans. Using transcriptomic analyses, the gene network controlling/regulating Fe3O4 nanoparticle biogenesis in A. ferrooxidans was proposed, excavating the candidate hub genes for Fe3O4 nanoparticle formation in A. ferrooxidans. Based on this information, a sequential model for Fe3O4 nanoparticle synthesis in A. ferrooxidans was hypothesized. It lays the groundwork for further clarifying the feature of Fe3O4 nanoparticle synthesis.

Cyclic‐Phenoxaphosphinine‐Based Mixed Phosphonium‐Iodonium Ylides with Electron‐Withdrawing Substituents – Synthesis and Structural Features

AbstractA series of phosphonium ylides and mixed phosphonium‐iodonium ylides based on cyclic phenoxaphosphinine has been synthesized, representing a new structural type of ylides. The influence of the electron‐withdrawing substituents of various nature on the stability and physicochemical properties of phenoxaphosphonium ylides is discussed. Our findings reveal a progressive reduction in ylide stability as the carbonyl group is replaced first with a phosphonate group and then with a nitrile group. NMR data indicates that the presence of a cyclic phosphonium group results in a lowered energy barrier to rotation about the carbon‐carbon bond, both in phosphonium and mixed phosphonium‐iodonium ylides with α‐carboxyl substituents when compared to triarylphosphonium ylides. These experimental results are further supported and analyzed in the context of density functional theory (DFT) calculations.

Eco-friendly synthesis of various tri-substituted imidazole derivatives by using a novel functionalized NCP@SiO3PrNHPrSiO3TiO2 under solvent-free conditions

In this research, a novel NCP@SiO3PrNHPrSiO3TiO2 nano catalyst has been designed, synthesized and fully characterized using various analytical techniques such as; XRD, FT-IR, SEM, EDS, BET and TG analyses. The catalytic activity of NCP@SiO3PrNHPrSiO3TiO2 was also employed for the synthesis of tri-substituted imidazoles via three-component condensation reactions of aldehydes, benzyl and NH4OAc under solvent-free conditions. This synthesis features environmentally benign, short reaction time, efficiency, and feasibility of large-scale synthesis compared to classical reactions.

Luminescent properties of the structures with embedded silicon nanoclusters: Influence of technology, doping and annealing (Review)

Detection of photoluminescence (PL) in traditionally non-luminescent Si material (a typical indirect band semiconductor) attracts great attention both in the scientific aspect and for applications in the field of micro- and nanoelectronics and photoelectronics. Despite the success in technology and understanding of many features inherent to its PL characteristics, many problems have not yet been resolved. In particular – what is the origin of PL lines: quantum size, molecular complexes within SiO2, interface or volume localized states, etc. How to achieve the increase in the PL intensity and to provide excitation of it in different parts of the spectrum. The proposed review systematizes results of studies associated with these problems concerning the original technologies for creation of Si nanocrystals (nc-Si) and various research methods. In conclusion, we summarize the results on the properties of nc-Si-SiO2 luminescent structures depending on their technology of synthesis, photo- and structural features and application prospects for micro- and nanoelectronics as well as photoelectronics.

Semicarbazones of alkyl 3-nitropyruvates: Synthesis and structural features

Semicarbazones of alkyl 3-nitropyruvates were obtained by the reaction between alkyl 3-bromo-3-nitroacrylates and semicarbazides. The products were formed as E/Z isomer mixtures from which some representatives of the individual isomers were isolated. The possibility of their isomerization was shown.

Total Synthesis and Structure Confirmation of (-)-Asimitrin, a C37 Annonaceous Acetogenin with a Hydroxylated Adjacent Bis-Tetrahydrofuran Core.

The total synthesis and structure confirmation of the potent cytotoxic agent (-)-asimitrin (1), a C37 annonaceous acetogenin having a hydroxylated adjacent bis-tetrahydrofuran (THF) core, are described. The present synthesis features a highly stereoselective, chelate-controlled intramolecular amide enolate alkylation (IAEA) for the synthesis of key intermediate 17-hydroxy-16,17-erythro-16,19-trans-THF 6, our direct ketone synthesis/l-Selectride reduction protocol for stereoselective introduction of the C(21)-C(34) unit, Sharpless asymmetric dihydroxylation (SAD), and internal Williamson etherification for construction of the 20,23-trans-THF ring.

Total Synthesis of Metaphanine and Oxoepistephamiersine

AbstractHerein, we report a concise and divergent synthesis of the complex hasubanan alkaloids metaphanine and oxoepistephamiersine from commercially available and inexpensive cyclohexanedione monoethylene acetal. Our synthesis features a palladium‐catalyzed cascade cyclization reaction to set the tricyclic carbon framework of the desired molecules, a regioselective Baeyer–Villiger oxidation followed by a MeNH2 triggered skeletal reorganization cascade to construct the benzannulated aza[4.4.3]propellane, and a strategically late‐stage regio‐/diastereoselective oxidative annulation of sp3 C−H bond to form the challenging THF ring system and hemiketal moiety in a single step. In addition, a highly enantioselective alkylation of cyclohexanedione monoethylene acetal paved the way for the asymmetric synthesis of target molecular.

Total Synthesis of Metaphanine and Oxoepistephamiersine.

Herein, we report a concise and divergent synthesis of the complex hasubanan alkaloids metaphanine and oxoepistephamiersine from commercially available and inexpensive cyclohexanedione monoethylene acetal. Our synthesis features a palladium-catalyzed cascade cyclization reaction to set the tricyclic carbon framework of the desired molecules, a regioselective Baeyer-Villiger oxidation followed by a MeNH2 triggered skeletal reorganization cascade to construct the benzannulated aza[4.4.3]propellane, and a strategically late-stage regio-/diastereoselective oxidative annulation of sp3 C-H bond to form the challenging THF ring system and hemiketal moiety in a single step. In addition, a highly enantioselective alkylation of cyclohexanedione monoethylene acetal paved the way for the asymmetric synthesis of target molecular.

Stereoselective total syntheses of varioxiranol B and varioxiranol C

The enantioselective total syntheses of varioxiranol B and varioxiranol C, two naturally occurring salicyl alcohols isolated from the marine-derived fungus Emericella variecolor, have been accomplished for the first time by convergent strategies. The synthesis features rapid access to the key chiral backbone from chiral pool 2, 3-O-isopropylidene-d-ribose and the formation of styrene skeleton employing olefin cross-metathesis and the acid-catalyzed one-pot deacetylation and acetonide deprotection.

Design and Synthesis of Spirochroman‐2‐on‐4,1'‐indan‐7'‐ol and Its Application for Synthesizing Chiral Monophosphinite Ligands†

Comprehensive SummaryThe design and synthesis of spirochroman‐2‐on‐4,1'‐indan‐7'‐ol (SCIOL) and its application for synthesizing chiral monophosphinite ligands are reported. The synthesis features a tandem double Friedel‐Crafts reaction/lactonization to construct the spiro framework and the desired racemic SCIOL was obtained via 6 steps with a total yield of 44.5%. Using an inclusion resolution with N‐benzylcinchonidinium chloride, the optical SCIOL could be obtained in good yields on a gram scale. The preliminary studies indicated that the corresponding chiral spiro monophosphinite ligands exhibit high catalytic activity and enantioselectivity (up to 94% ee) in the rhodium‐catalyzed asymmetric hydrogenation of N‐acetyl dehydroamino esters. These outcomes highlight the significant potential of SCIOL as a useful framework for the development of chiral spiro ligands.

Total Synthesis of the Reported Structure of Neaumycin B.

The stereoselective total synthesis of structure 1 assigned to the macrolide natural product neaumycin B is reported in a 2.3% overall yield on 90 mg scale. The synthesis features a gram-scale nickel-catalyzed reductive cross-coupling/spiroketalization tactic to construct the spiroketal core of neaumycin B. The stereostructures of the C3-C6, C8-C14, and C20-C41 segments of synthetic neaumycin B were unambiguously verified by X-ray crystallography.

Synthesis, photophysical and photochemical features of a Morita-Baylis-Hillman adduct derivative bearing a triphenylamine moiety

A new Morita-Baylis-Hillman Adduct (MBHA) derivative 7 was designed and synthesized to obtain a reactive molecule potentially capable of labelling basic amino acid residues. Compound 7 was easily prepared and characterized from the point of view of its photophysical and photochemical features before then to be used in labelling experiments with amino acid.

Improved Thermal and Chemical Stability of Oxynitride Phosphor from Facile Chemical Synthesis for Vehicle Cornering Lights

AbstractOrange Eu2+‐doped phosphors are essential for light‐emitting diodes for cornering lights to prevent fatal road accidents at night, but such phosphors require features of high thermal, chemical stability and facile synthesis. This study reports a series of yellow‐orange‐red emitting SrAl2Si3ON6:Eu2+ oxynitride phosphors, derived from the SrAlSi4N7 nitride iso‐structure by replacing Si4+−N3− with Al3+−O2−. The introduction of a certain amount of oxygen enabled the facile synthesis under atmospheric pressure using the air‐stable raw materials SrCO3, Eu2O3, AlN and Si3N4. SrAl2Si3ON6 has a smaller band gap and lower structure rigidity than SrAlSi4N7 (5.19 eV vs 5.50 eV, Debye temperature 719 K vs 760 K), but exhibits higher thermal stability with 100 % of room temperature intensity remaining at 150 °C compared to 85 % for SrAlSi4N7. Electron paramagnetic resonance, thermoluminescence and density functional theory revealed that the oxygen vacancy electron traps compensated the thermal loss. Additionally, no decrease in emission intensity was found after either being heated at 500 °C for 2 hours or being immersed in water for 20 days, implying both of the thermal and chemical stability of SrAl2Si3ON6:Eu2+ phosphors. The strategy of oxynitride‐introduction from nitride promotes the development of low‐cost thermally and chemically stable luminescent materials.

Improved Thermal and Chemical Stability of Oxynitride Phosphor from Facile Chemical Synthesis for Vehicle Cornering Lights.

Orange Eu2+ -doped phosphors are essential for light-emitting diodes for cornering lights to prevent fatal road accidents at night, but such phosphors require features of high thermal, chemical stability and facile synthesis. This study reports a series of yellow-orange-red emitting SrAl2 Si3 ON6 :Eu2+ oxynitride phosphors, derived from the SrAlSi4 N7 nitride iso-structure by replacing Si4+ -N3- with Al3+ -O2- . The introduction of a certain amount of oxygen enabled the facile synthesis under atmospheric pressure using the air-stable raw materials SrCO3 , Eu2 O3 , AlN and Si3 N4 . SrAl2 Si3 ON6 has a smaller band gap and lower structure rigidity than SrAlSi4 N7 (5.19 eV vs 5.50 eV, Debye temperature 719 K vs 760 K), but exhibits higher thermal stability with 100 % of room temperature intensity remaining at 150 °C compared to 85 % for SrAlSi4 N7 . Electron paramagnetic resonance, thermoluminescence and density functional theory revealed that the oxygen vacancy electron traps compensated the thermal loss. Additionally, no decrease in emission intensity was found after either being heated at 500 °C for 2 hours or being immersed in water for 20 days, implying both of the thermal and chemical stability of SrAl2 Si3 ON6 :Eu2+ phosphors. The strategy of oxynitride-introduction from nitride promotes the development of low-cost thermally and chemically stable luminescent materials.

Microwave-Assisted, Ionic Liquid-Catalyzed Synthesis of 1,2-Disubstituted Benzimidazoles under Solvent-Free Conditions

An efficient method for the synthesis of 1,2-disubstituted benzimidazoles has been developed from 1,2‐diaminobenzenes and aldehydes using 1-butyl-3-methylimidazolium ([Bmim]BF4) as a catalyst under solvent-free conditions. Various products were obtained in good to excellent yields under microwave irradiation. The synthesis features some advantages such as short reaction time, environmentally benign conditions, simple work-up procedure, and high efficiency.