Base mediated direct C–H amination for pyrimidines synthesis from amidines and cinnamaldehydes using oxygen as green oxidants

A direct metal-free C-H amination reaction of cinnamaldehydes and amidines to realize the synthesis of polysubstituted pyrimidines was developed in the presence of base. This greener synthetic methodology provides a straightforward approach to the synthesis of a variety of pyrimidine derivatives under mild reaction condition using oxygen as sole oxidants.

Selective Synthesis of 1,2-Diarylpyrrolo[3,4-b]pyridine-5,7- diones via Cyclization Reaction of β-Enamino Imides with Cinnamaldehydes

The novel 1,2-diaryl substituted pyrrolo[3,4-b]pyridine-5,7-diones were selectively synthesized in high yields by the base catalyzed cyclization reaction of 3-arylamino-l-methyl-lH-pyrrole-2,5-diones with cinnamaldehyde and its derivatives in acetonitrile at room temperature. However, when piperidinium trifluoroacetate was employed as catalyst, the reaction afforded a mixture of 1,2-diaryl and 1,4-diaryl substituted pyrrolo[3,4-b]pyridine-5,7-diones in comparable yields.

Silica-modified Pt/TiO_(2) catalysts with tunable suppression of strong metal-support interaction for cinnamaldehyde hydrogenation

Tuning Strong Metal-support Interactions(SMSI)is a key strategy to obtain highly active catalysts,but conventional methods usually enable TiO_(x) encapsulation of noble metal components to minimize the exposure of noble metals.This study demonstrates a catalyst preparation method to modulate a weak encapsulation of Pt metal nanoparticles(NPs)with the supported TiO_(2),achieving the moderate suppression of SMSI effects.The introduction of silica inhibits this encapsulation,as reflected in the characterization results such as XPS and HRTEM,while the Ti^(4+) to Ti^(3+) conversion due to SMSI can still be found on the support surface.Furthermore,the hydrogenation of cinnamaldehyde(CAL)as a probe reaction revealed that once this encapsulation behavior was suppressed,the adsorption capacity of the catalyst for small molecules like H_(2) and CO was enhanced,which thereby improved the catalytic activity and facilitated the hydrogenation of CAL.Meanwhile,the introduction of SiO_(2) also changed the surface structure of the catalyst,which inhibited the occurrence of the acetal reaction and improved the conversion efficiency of C=O and C=C hydrogenation.Systematic manipulation of SMSI formation and its consequence on the performance in catalytic hydrogenation reactions are discussed.

Comparison and Quality Assessment of Cassia Bark (Cortex Cinnamomi) by Thin Layer Chromatography

Aim To differentiate the genuine cassia bark from its substitutes and adulterants. Methods Six components, phenylpropyl acetate, cinnamyl acetate, cinnamaldehyde, cinnamyl alcohol, coumarin, and cinnamic acid were used as characteristic markers, and an optimized TLC method was developed. Results The TLC profile of cassia bark is similar to its closely related variety Cinnamomum cassia Presl var. macrophyllum Chu but significantly different from other six Cinnamomum species. High content of phenylpropyl acet...

Chemoselective Transfer Hydrogenation of Cinnamaldehyde over Activated Charcoal Supported Pt/Fe3O4 Catalyst

A variety of spherical and structured activated charcoal supported Pt/Fe3O4 composites with an average particle size of ~100 nm have been synthesized by a self-assembly method using the difference of reduction potential between Pt （Ⅳ） and Fe （Ⅱ） precursors as driving force. The formed Fe3O4 nanoparticles （NPs） effectively prevent the aggregation of Pt nanocrystallites and promote the dispersion of Pt NPs on the surface of catalyst, which will be favorable for the exposure of Pt active sites for high-efficient adsorption and contact of substrate and hydrogen donor. The electron-enrichment state of Pt NPs donated by Fe304 nanocrystallites is corroborated by XPS measurement, which is responsible for promoting and activating the terminal C=O bond of adsorbed substrate via a vertical configuration. The experimental results show that the activated charcoal supported Pt/Fe3O4 catalyst exhibits 94.8% selectivity towards cinnamyl alcohol by the transfer hydrogenation of einnamaldehyde with Pt loading of 2.46% under the optimum conditions of 120 ℃ for 6 h, and 2-propanol as a hydrogen donor. Additionally, the present study demonstrates that a high-efficient and recyclable catalyst can be rapidly separated from the mixture due to its natural magnetism upon the application of magnetic field.

Hydrogenation of Cinnamaldehyde to Cinnamyl Alcohol over An Ultrafine Co-B Amorphous Catalyst

A novel Co-B amorphous alloy catalyst in the form of ultrafine particles was prepared by chemical reduction of CoCl2 with aqueous NaBH4, which exhibited excellent activity and selectivity during the hydrogenation of cinnamaldehyde to cinnamyl alcohol in liquid phase. The optimum yield of cinnamyl alcohol was 87.6%, much better than the yield of using Raney Ni, Raney Co and other Co-based catalysts.

Confinement effect of carbon nanotubes on the product distribution of selective hydrogenation of cinnamaldehyde

The catalytic activity of metal catalysts can be modulated by confinement within the channels of carbon nanotubes(CNTs).Here,we show that the product distribution of cinnamaldehyde hydrogenation can be modified by confinement of Ru nanoparticles in CNTs.A catalyst composed of Ru nanoparticles dispersed on the exterior walls of CNTs gave hydrocinnamaldehyde as product.In contrast,confinement of the Ru nanoparticles within CNT channels facilitated hydrogenation of C=O bonds and complete hydrogenation,and both cinnamyl alcohol and hydrocinnamyl alcohol formed in addition to hydrocinnamaldehyde.High‐resolution transmission electron microscopy,Raman spectroscopy,hydrogen temperature‐programmed reduction,and hydrogen temperature‐programmed desorption were used to investigate the characteristics of the catalysts.The results indicate that the different interactions between the confined Ru nanoparticles and the exterior and interior walls of the CNTs,as well as spatial restriction and enrichment within the narrow channels likely play important roles in modulation of the product distribution.

In vitro antibacterial activity and major bioactive components of Cinnamomum verum essential oils against cariogenic bacteria,Streptococcus mutans and Streptococcus sobrinus

Objective:To evaluate the antibacterial activity of Cinnamomum verum(C.verum) from32 different essential oils against cariogenic bacteria,Streptococcus mutans(S.mutans)and Streptococcus sobrinus(S.sobrinus).Methods:The antibacterial activities of each essential oil were individually investigated against S.mutans and S.sobrinus.The essential oil of C.verum was selected for further evaluation against S.mutans and S.sobrinus.Gas chromatography mass spectrometry was used to determine the major constituents of C.verum essential oil.In addition,the minimum inhibitory concentration(MIC) and minimum bactericidal concentration of the most effective constituent was investigated.Results:The essential oil from C.verum exhibited the greatest antibacterial activity.Gas chromatography mass spectrometry analysis revealed that the major components of C.verum essential oil were cinnamaldehyde(56.3%),cinnamyl acetate(7.1%) and bphellandrene(6.3%).The MIC of cinnamaldehyde was measured using broth dilution assays.The MIC of cinnamaldehyde was 0.02%(v/v) against both bacterial strains tested.The minimum bactericidal concentration of cinnamaldehyde against S.mutans and S.sobrinus were 0.2% and 0.1%(v/v),respectively.Conclusions:The essential oil of C.verum and its major component cinnamaldehyde possessed considerable in vitro antibacterial activities against cariogenic bacteria,S.mutans and S.sobrinus strains.These results showed that the essential oil of C.verum and its bioactive component,cinnamaldehyde,have potential for application as natural agents for the prevention and treatment of dental caries.

Pt-Re/rGO bimetallic catalyst for highly selective hydrogenation of cinnamaldehyde to cinnamylalcohol

In the present work, a series of Pt-based catalysts, alloyed with a second metal, i.e., Re, Sn, Er, La, and Y, and supported on activated carbon, ordered mesoporous carbon, N-doped mesoporous carbon or reduced graphene oxide(rGO), have been developed for selective hydrogenation of cinnamaldehyde to cinnamylalcohol. Re and rGO were proved to be the most favorable metal dopant and catalyst support, respectively. Pt_(50) Re_(50)/rGO showed the highest cinnamylalcohol selectivity of 89% with 94% conversion of cinnamaldehyde at the reaction conditions of 120 °C, 2.0 MPaH_2 and 4 h.

Layered double hydroxide-like Mg_3Al_(1–x)Fe_x materials as supports for Ir catalysts: Promotional effects of Fe doping in selective hydrogenation of cinnamaldehyde

Supported Ir catalysts were prepared using layered double hydrotalcite‐like materials,such as Mg3Al1-xFex,containing Fe and Al species in varying amounts as supports.These Ir catalysts were applied for the selective hydrogenation of cinnamaldehyde(CAL).When x was changed from 0(Ir/Mg3Al)to 1(Ir/Mg3Fe),the rate of CAL hydrogenation reached a maximum at approximately x=0.25,while the selectivity to unsaturated alcohol,i.e.,cinnamyl alcohol,monotonously increased from 44.9%to 80.3%.Meanwhile,the size of the supported Ir particles did not change significantly with x,remaining at 1.7-0.2 nm,as determined by transmission electron microscopy.The chemical state of Ir and Fe species in the Ir/Mg3Al1-xFex catalysts was examined by temperature programmed reduction by H2 and X‐ray photoelectron spectroscopy.The surface of the supported Ir particles was also examined through the in‐situ diffuse reflectance infrared Fourier‐transform of a probe molecule of CO.On the basis of these characterization results,the effects of Fe doping to Mg3Al on the structural and catalytic properties of Ir particles in selective CAL hydrogenation were discussed.The significant factors are the electron transfer from Fe2+in the Mg3Al1–xFex support to the dispersed Ir particles and the surface geometry.

Surface titanium oxide loaded on a special alumina as high-performance catalyst for reduction of cinnamaldehyde by isopropanol

A nanocomposite catalyst with a nonstoichiometric titanium oxide loaded on a special nanotubular alumina(γ‐Al2O3‐nt)was developed and used to reduce cinnamaldehyde to cinnamyl alcohol with sacrificial isopropanol,i.e.,a Meerwein‐Ponndorf‐Verley type reaction.The deposition process produced a highly disperse layer of titanium oxide on the surface of aγ‐Al2O3‐nt support.After a reduction treatment,the as‐prepared TiOx/γ‐Al2O3‐nt was a highly efficient catalyst for the hydrogen transfer reaction between isopropanol and cinnamaldehyde.Selectivity for cinnamic alcohol was higher than99%and the conversion of cinnamaldehyde was higher than95%.The regular morphology of theγ‐Al2O3‐nt support with homogeneous surface sites and the uniformly dispersed titanium oxide featured a high concentration surface Ti(III)species.These factors contributed to the high performance of the TiOx/γ‐Al2O3‐nt catalyst.

β-Cyclodextrin Promoted Oxidation of Cinnamaldehyde to Natural Benzaldehyde in Water

A facile and efficient procedure has been developed systematically for the oxidative cleavage of cinna-maldehyde to benzaldehyde by sodium hypochlorite with water as the only solvent in the presence of β-cyclodextrin （abbreviated as β-CD）. Different factors influencing cinnamaldehyde oxidation e.g. reaction temperature, the amount of catalyst and oxidant, have been investigated. The yield of benzaldehyde reaches 76% under the optimum conditions （333 K, 4 h, molar ratio of cinnamaldehyde to β-CD is 1：1）. Furthermore, a feasible reaction mecha-nism including the formation of benzaldehyde and the two main byproducts （phenylacetaldehyde and epoxide of cinnamaldehyde） has been proposed.

Comparative Study of the Modification of Coal Tar Pitch for Higher Carbonization Yield and Better Properties

Parent coal tar pitch(CTP)was modified with boric acid(BA),cinnamaldehyde(CMA)and the mixture of BA and CMA,respectively.The parent CTP and three modified CTPs were characterized by elemental analysis,thermogravimetric analysis,Fourier transform infrared(FT-IR)spectroscopy and scanning electron microscopy.The four samples were carbonized at different temperatures and resultant carbonized products were characterized by FT-IR spectroscopy,X-ray diffraction and polarized-light microscopy.The results show that the morphologies and carbonization behaviors of the parent CTP and modified CTPs are quite different.The carbonization yield of the CTP modified with the mixture of BA and CMA is higher than that of CTP modified with BA or CMA only.In addition,the modification of CTP with 7 g of BA and 10 ml of CMA results in an increase in carbonization yield by5.64%.During the pyrolysis of modified CTPs,the dehydration of BA or the distillation of CMA occurs at the temperature lower than 300°C,and methyl and methylene groups of the modified CTPs disappear gradually as temperature rises.Furthermore,the modification of CTP by the mixture of BA and CMA results in more intensive mesophase spheres than other modified CTPs,and the modified CTP is easier to be carbonized to form graphitic carbon.

Chemical and Biological Comparative <i>in Vitro</i>Studies of Cinnamon Bark and Lemon Peel Essential Oils

Cinnamon and lemon are the oldest plants which possess a rising popularity due to their therapeutic potential from centuries. Cinnamomum zeylanicum and lemon (Citrus lemon L.) have been subjected to extensive research. Their essential oils were extracted by steam distillation from selected plants and their chemical compositions were determined by the GC-MS system. Cinnamon and lemon essential oils were examined for antioxidant activity by ABTS method which showed the ability to inhibit lipid per-oxidation. On the other hand, in antimicrobial investigations, cinnamon and lemon essential oils have inhibitory effect against Gram positive bacteria (Staphylococcus aureus) and Gram negative bacteria (Escherichia coli) using Muller Hinton agar medium. The essential oils of cinnamon and lemon showed antifungal effects which were tested against (Candida albicans). The volatile oil of cinnamon bark has been found to be highly effective against all the tested bacteria and fungi. However, lemon peel essential oil has shown medium inhibition for Gram positive bacteria (Staphylococcus aureus). On the other hand, the cytotoxic activities of the essential oils were tested on hepatocellular carcinoma and colorectal carcinoma. Essential oils have shown good activities on the cell lines. Essential oil of cinnamon showed more inhibition rate than essential oil of lemon. This study reported the importance of both cinnamon and lemon volatile oils and recommends that cinnamon and lemon can be used as an active therapy for humans.

Producing of cinnamyl alcohol from cinnamaldehyde over supported gold nanocatalyst

Chemoselective hydrogenation of unsaturated aldehyde to unsaturated alcohol has attracted growing interests in recent years due to its widespread applications in fine chemicals.However,the hydrogenation of the C=O bond was thermodynamically and kinetically unfavorable over the hydrogenation of the C=C bond.Thus,to obtain the unsaturated alcohol from the unsaturated aldehyde is very difficult in most of the catalytic systems.In this work,ZnAl-hydrotalcite-supported cysteine-capped Au25 nanoclusters were used as the precatalysts for chemoselective hydrogenation of cinnamaldehyde to cinnamyl alcohol.The catalyst showed stable high selectivity(~95%)at prolonged reaction time and complete conversion of the substrate.According to the results of the control experiments,the in-situ DRIFTS of the substrate under high pressure of hydrogen and the 27Al MAS-NMR spectroscopy,we proposed that the difference of the preferential adsorption of the C=O bond to that of the C=C bond was derived from the nature of the support of the gold catalysts.

Metal-organic framework-derived Co-C catalyst for the selective hydrogenation of cinnamaldehyde to cinnamic alcohol

The liquid phase selective hydrogenation of cinnamaldehyde has been investigated over the catalysts Co-C-T(T=400-700℃),which were derived from the carbonization of the MOF precursor Co-BTC at different temperatures in inert atmosphere.Co-C-500 exhibited a higher conversion(85.3%)than those carbonized at other temperatures,with 51.5%selectivity to cinnamyl alcohol,under a mild condition(90℃,4 h,2 MPa H_(2),solvent:9 ml ethanol and 1 ml water).The high catalytic activity of Co-C-500 can be ascribed to the large specific surface area of the catalyst,the uniformly dispersed metallic cobalt nanoparticles,and the more defect sites on the carbon support.Moreover,Co-C-500 showed excellent reusability in 5 successive cycles,mainly related to the uniformly dispersed cobalt nanoparticles embedded in carbon support.

Effect of Transition Metals on Selective Hydrogenation of Cinnamaldehyde over Pt/ZrO_2 Catalysts

The effect of transition metals (Cr, Mn, Fe, Co and Ni) on the hydrogenation ofcinnamaldehyde over Pt/ZrO_2 catalysts was studied in ethanol at 343K under 2.0MPa H_2 pressure.PtCo/ZrO_2 and PtFe/ZrO_2 catalysts exhibit high selectivity and activity of hydrogenation for C=O(93.8% at 87.3% conversion and 83.6% at 88.6% conversion, respectively), and PtNi/ZrO_2 exhibitshigh selectivity of hydrogenation for C=C (64.3% at 70.6% conversion). In the presence of traceH_2O and NaOH, over the PtNi/ZrO_2 (0.4wt%Ni) catalyst the selectivity to hydrocinnamaldehydereaches 90.6% and the conversion of cinnamaldehyde is 90.5%.

Bioguided Fractionation and Purification of Natural Bioactives Obtained from<i>Alpinia conchigera</i>Water Extract with Melanin Inhibition Activity

Crude extracts of Alpinia conchigera a species from the Malaysian Ginger (Zingiberaceae) family and its fractions obtained from various extraction methods were assayed for melanogenesis inhibition activity and cell viability. The crude extract obtained from the ethanolic extraction and the super critical fluid extraction did not exhibit significant melanin inhibition activity and was shown to be toxic to the melanocyte cells in comparison to the water extract. The crude aqueous extracts displayed melanin inhibition of 96.38 ± 1.60% and cell viability 109.90 ± 8.32% at a concentration of 500 μg/mL. Bioassay guided fractionation was performed on the water extracts to isolate the active compounds. The actives were identified as trans-cinnamaldehyde and chavicol glucopyranoside with both compound showing potent anti-melanogenesis activity. At 4.9 μg/ml, both trans-cinnamaldehyde and chavicol glucopyranoside gave 85% inhibition of melanin formation in vitro with 77% and 97% cell viability respectively. In comparison, kojic acid, a known skin lightening agent showed 90.0% inhibition at 100 μg/mL. The bioactive composition comprising the extract, active fraction, purified compounds or mixture thereof of Alpinia conchigera may be used for cosmetic and pharmaceutical applications, particularly for the purposes of reducing skin pigmentation.

Effect of cinnamaldehyde on Rhizopus stolonifer and on the conservation of sweet potato

Objectives:Rhizopus stolonifer,which causes soft rot of sweet potato,has resulted in substantial loss of economy postharvest.Materials and Methods:The antifungal effect and mechanism of cinnamaldehyde(CIN)against R.stolonifer were explored by biochemical analysis and RNA-sequencing in this research,and the edible quality of CIN-treated sweet potato was evaluated.Results:The results showed that CIN inhibited the growth of R.stolonifer and reduced the incidence of soft rot in sweet potato at a minimum inhibitory concentration of 1000μL/L.The damage of the cell walls of R.stolonifer by CIN was associated with the upregulation of CHT1.Cytosolic leakage and malondialdehyde content increased following CIN-treatment,which was correlated with increased reactive oxygen species levels and decreased catalase activity.Upregulation of ERG genes and oxidative stress-related genes following CIN treatment was associated with impaired cell membrane integrity.The mitochondrial structure of R.stolonifer was damaged by CIN treatment resulting in decreased respiration rates and ATP production,which was correlated with lower expression levels of IDH1,COX4,and QCR7.Conclusions:Our research suggests that the inhibition of CIN on R.stolonifer was related to the disruption of its normal gene expression network,and CIN maintained the nutritional and edible quality of sweet potato.This study provides valuable insights into the antifungal mechanism of CIN on R.stolonifer and the maintenance of root quality,which contributes to the effcient use of CIN for controlling soft rot in sweet potato.

通过二维沸石调节铂的氢化选择性

不饱和醇是一类重要的医药中间体,然而C=C加氢比C=O加氢反应更具有热力学优势,因此由不饱和醛合成不饱和醇具有挑战性.为解决这一问题,需要寻求一种具有可调控选择性的氢化催化剂.二维沸石的高长径比和大量的末端基团作为锚定位点,使其不仅能作为催化剂载体,还可以有效地调节催化剂性能.本研究利用二维沸石IPC-1P作为铂纳米颗粒的载体,成功制备出异相催化剂Pt@IPC-1P.铂纳米颗粒的尺寸小于2 nm且均匀地分布在IPC-1P上.令人惊喜的是,Pt@IPC-1P催化剂对不饱和醇的选择性超过了90%,并实现了接近100%的催化转化率,远超其他铂基催化剂.理论计算证实,二维沸石IPC-1P在肉桂醛向肉桂醇的转化过程中起到了积极作用,其放热效应能量高于苯丙醛.这项工作展现了二维沸石在催化有机物转化领域具有广阔的应用前景.