Heterocyclic Aldehydes Research Articles

Facile one-pot synthesis of N-fused 1,2,4-triazoles via oxidative cyclization using manganese dioxide

A facile one-pot synthesis of N-fused 1,2,4-triazoles from heterocyclic hydrazines and aldehydes is reported. The reaction is efficiently promoted by manganese dioxide to afford the desired products mostly in high yields and in relatively short times. The mild nature of the synthesis, cheap oxidizing agent, and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.

A New Branch of the Diversity-Oriented Synthesis Based on 4-Oxoalkane-1,1,2,2-tetracarbonitriles: Synthesis of Cyano-Substituted Iminofuran Derivatives

4-Oxo-3,4-diphenylbutane-1,1,2,2-tetracarbonitrile reacted with aliphatic, aromatic, and heterocyclic aldehydes in the presence of ammonium acetate to afford previously unknown iminofuran derivatives, 5-imino-4-(2-oxo-1,2-diphenylethyl)tetrahydrofuran-3,3,4-tricarbonitriles.

Photoinduced one-pot synthesis of hydroxamic acids from aldehydes through in-situ generated silver nanoclusters

Hydroxamic acids have attracted significant attention due to their widespread use in applied chemistry. In this report, a modified Angeli–Rimini method has been achieved via the visible light-mediated catalytic transformation of a variety of heterocyclic, aromatic and aliphatic aldehydes 1a–j to their corresponding hydroxamic acids 2a–j in 81–93% yield. The unique ability of vitamin K3 as a photoredox catalyst to expedite the development of completely new reaction mechanisms and to enable the construction of challenging carbon–nitrogen bonds has been investigated. It is shown for the first time that the vitamin K3 and aldehyde are largely responsible for rapid in situ reduction of Ag+ ions to catalytic photoluminescent Ag nanoclusters that possess a bandgap energy of 2.87 eV and are less than 2 nm in size. A mechanism for this reaction has been proposed and is supported by UV–Vis, TEM, ESI/MS, FT-IR, 1H NMR and 13C NMR analyses. The investigated method utilizes readily available reagents and produces the hydroxamic acids in high yields without the formation of side products, making it simple, practical and cost-effective.

Evaluation of the Optical and Structural Properties of Constructed Bis-indole Derivatives Using (Sm2O3/SiO2) Catalyst

(SiO2/Sm2O3) was successfully synthesized and examined using scanning electron microscopy; X-ray diffraction and Fourier transform infrared spectroscopy. Obtained data shows the formation of crystalline phase superimposed over the silicate amorphous matrix. The synthesized catalyst was used for eco-friendly synthesis of bis-indole derivatives. Two moles of indole and different aromatic aldehyde were mixed and heterocyclic aldehydes have been adopted in-expensive, recyclable, easily prepared and nontoxic catalyst (SiO2/Sm2O3) under solvent free conditions. The chemical structures of the synthesized compounds have been introduced and correlated with UV/vis. optical absorption spectra in combination with (HOMO-LUMO) through experimental spectrophotometric data in both direct-indirect transitions and that obtained based of density functional theory (DFT).

Three-Component One-Pot Synthesis of New 2,5,6,7- and 2,5,8,10-Substituted Pyrimido[4,5-b]quinoline-4,6-diones and -2,4,6-Triones

A series of new pyrimido[4,5-b]quinoline derivatives was synthesized by three-component cyclocondensation of 2-R1-6-aminopyrimidine-4-ones, 5,5-dimethylcyclohexane-1,3-dione (dimedone), and aromatic or heterocyclic aldehydes in a water medium in the presence of triethylbenzylammonium chloride. The replacement of the primary amino group in the position 6 of the key 6-aminopyrimidin-4-one with the secondary amino group led to the formation of 10-substituted analogs of pyrimido[4,5-b]quinolines which are of interest for biological screening.

Heterogeneous Iron-Containing Carbon Gels As Catalysts for Oxygen and Carbon Dioxide Electroreductions – Rotating Ring-Disk Voltammetric Studies

There has been growing interest in the development of highly active catalysts for electroreduction of oxygen that could be effectively utilized in low-temperature fuel cells. The important practical issue is related to the need of lowering costs of catalysts by substituting the noble metals with inexpensive abundant elements. In this respect materials containing metallic moieties coordinated by nitrogen atoms embedded in the carbon matrix (M-N-C) are recognized as most suitable candidates to replace platinum catalysts. More recently, the approach of using such biomimetic centers has been considered for the carbon dioxide reduction, the reaction which permits generation of carbon-based chemicals, fuels or syngas. Since both reactions (O2 and CO2 reductions) are characterized by slow kinetics and may proceed through different pathways producing various products, their efficiency and selectivity still remain fundamental problems for practical applications. It is well established that the best performing M-N-C catalysts (with high specific surface area and large fraction of micropores) are produced from nitrogen-containing polymeric precursors. In these study we present a new type of self-supporting M-N-C materials, namely nitrogen and sulfur co-doped iron containing highly porous carbon gels (obtained through pyrolysis of organic gels) as efficient non-precious metal catalysts for both the oxygen and carbon dioxide electroreductions. The precursors of the catalysts were prepared via the sol-gel polycondensation (induced with iron(III) cations) of resorcinol together with the mixture of two heterocyclic aldehydes containing nitrogen and sulfur. The role of S is to produce carbon gels with high specific surface areas (e.g. when compared to carbon gels containing solely N heteroatom). It is commonly accepted that rotating ring(platinum)-disk(glassy carbon) electrode voltammetry can be effective diagnostic tool for elucidation of the performance and selectivity (towards water or hydrogen peroxide) of the oxygen electroreduction. We are going to demonstrate that a combination of the rotating ring-disk electrode methodology and stripping type voltammetry (at platinum ring) can be also used for the determination of the reaction mechanism, competitive formation (evolution) of hydrogen, and determination of CO-type adsorbates generated at the catalyst during the CO2 electroreduction.

A Metal‐Free Oxidative Carboannulation Approach towards Synthesis of 2,3‐Diarylindenones and Its Regioisomers

AbstractA metal free, PIDA (Iodosobenzene diacetate) mediated radical oxidative annulation of aromatic aldehydes with 1,2‐diphenylethyne was developed, resulting an array of 2,3‐diaryl indenones in moderate to good yields. This methodology requires no preactivation of the aldehyde groups and involves activation of the C(sp)‐C(sp) bond of the internal alkyne by in situ generated acyl radical under metal free condition. This procedure is applicable to a large variety of functionalized substrates specially heterocyclic aldehydes and ortho hydroxyl aromatic aldehydes to give 2,3‐diaryl indenones. Interestingly, meta substituted aromatic aldehyde provided two regioisomers in 1:1 ratio when they were subjected to the experimental condition. These two regioisomers were isolated by column chromatography and their colour, spectral data and crystal structures were investigated.

Preparative microdroplet synthesis of carboxylic acids from aerobic oxidation of aldehydes.

Single liquid-phase and liquid-liquid phase reactions in microdroplets have shown much faster kinetics than that in the bulk phase. This work extends the scope of microdroplet reactions to gas-liquid reactions and achieves preparative synthesis. We report highly efficient aerobic oxidation of aldehydes to carboxylic acids in microdroplets. Molecular oxygen plays two roles: (1) as the sheath gas to shear the aldehyde solution into microdroplets, and (2) as the sole oxidant. The dramatic increase of the surface-area-to-volume ratio of microdroplets compared to bulk solution, and the efficient mixing of gas and liquid phases using spray nozzles allow effective mass transfer between aldehydes and molecular oxygen. The addition of catalytic nickel(ii) acetate is shown to accelerate further microdroplet reactions of this kind. We show that aliphatic, aromatic, and heterocyclic aldehydes can be oxidized to the corresponding carboxylic acids in a mixture of water and ethanol using the nickel(ii) acetate catalyst, in moderate to excellent yields (62-91%). The microdroplet synthesis is scaled up to make it preparative. For example, aerobic oxidation of 4-tert-butylbenzaldehyde to 4-tert-butylbenzoic acid was achieved at a rate of 10.5 mg min-1 with an isolated product yield of 66%.

One-Step Three-Component Synthesis of New 2,5,6,7-Functionalized 5,8-Dihydropyrido-[2,3-d]pyrimidin-4(3H)-ones

One-step three-component cyclocondensation of 2,6-disubstituted pyrimidin-4(3H)-ones with 1,3-dicarbonyl compounds and some aromatic and heterocyclic aldehydes on heating or under microwave irradiation afforded new functionally substituted 5,8-dihydropyrido[2,3-d]pyrimidin-4(3H)-ones. Conventional heating was found to be more advantageous. The effects of the 2-substituent in the initial pyrimidin-4(3H)-one and the nature of the dicarbonyl component on the product structure and yield were analyzed.

Search of new luminophores with predetermined physicochemical and chemical properties ХVІ. N-arylmethylene- and N–hetarylmethylene- substituted for polyvinylamine

Investigation of transformation of polyacrylamide (PAA) in the polyvinylamine (РVAm) the reaction of Hofmann and further transformation of NH2-groups polymer by the Leuckart—Wallach reaction. The reliability of the transformation of PAA into PVAm is confirmed by the reaction of diazotization and acylation of the samples obtained by PVA and by the color reactions of the PVAm transformation products. The structure of PVAm is also confirmed by data from IR spectroscopy and pH-metric titration. The product obtained is a vinylamine copolymer (up to 80%), acrylamide and acrylic acid. Syntheses of N-arylmethylene- and N-hetarylmethylene substituted PVAm, is carried out by the reduction alkylating of NH2-groups of РVAm by aromatic and heterocyclic aldehydes [5‑(4‑chlorophenyl)-2-(4-formylphenyl)oxazol-1,3, 5-(4-methoxyphenyl)-2-(4-formylphenyl)oxazol-1,3, 5‑(4‑methylphenyl)-2-(5-formylfuryl-2)oxazol-1,3, 5-(4-methoxyphenyl)-2-(5-formylfuryl-2)oxazol-1,3, 3,5-diphenyl-1-(4-formylphenyl)-2-pyrazoline, pyrene-3-aldehyde, possessing luminescence, in presence formic acid. The indicated derivatives of PVAm are got also by successive formation with NH2-groups of elementary links of grounds of Schiff and reduction of them NaBH4. The derivatives of PVAm containing N-arylmethylene and N‑hetarylmethylene groups [...–CH2−CH(NH−CH2−Ar) – ... and ... –CH2−CH(NH−CH2−Het) – ...), respectively], low-grade in water, nonpolar organic, partially soluble in polar solvents and readily soluble in acid solutions.The got standards of modified PVAm, containing elementary links of …–СН2−СН(NH−CH2−Ar)–… and ...–СН2−СН(NH−CH2−Het)–..., luminesce both in the hard state and in solutions. IR-specta (hard state) РVAm and modified foods is studied, spectrums of absorption and luminescence of N-arylmethylene- and N‑hetarylmethylene substituted for PVAm, (in solutions of the mixed solvent is ethyl acetate - formic acid). The fluorescence maxima of PVAm derivatives are shifted to the short-wave region in comparison with similar solutions for initial aldehydes due to the reduction of the chromophore chain through the replacement of the aldehyde group with methylene.

Ir(iii)-catalyzed ortho C-H alkylations of (hetero)aromatic aldehydes using alkyl boron reagents.

Transition-metal-catalyzed C-H alkylation reactions directed by aldehydes or ketones have been largely restricted to electronically activated alkenes. Herein, we report a general protocol for the Ir(iii)-catalyzed ortho C-H alkylations of (hetero)aromatic aldehydes using alkyl boron reagents as the coupling partner. Featuring aniline as an inexpensive catalytic ligand, the method was compatible with a wide variety of benzaldehydes, heterocyclic aldehydes, potassium alkyltrifluoroborates as well as a few α,β-unsaturated aldehydes. An X-ray crystal structure of a benzaldehyde ortho C-H iridation intermediate was also successfully obtained.

CHARACTERIZATION OF SACCHARIDE SUGAR IN CORN SEED (Zea Mays Saccharata) BY USING GAS CHROMATOGRAPHY MASS SPECTROMETRY METHOD

This study characterizes the saccharide sugar contained in whole sweet corn seeds by extracting using Ultrasound Assisted Solvent Extraction for 60 minutes with 24 kHz frequency using ethanol solvent with concentrations of 70%, 75%, 80%, and 85%. The concentrated extract was then characterized by using Gas Chromatography Mass Spectrometry (GCMS) method. Sample test conducted were tested to odor, color and shelf life of extract and determination of water content, ash content, and characterization of saccharide sugar from GCMS test. The odor and color test results show that the extract had a distinctive smell of sweet corn, yellow, and had the ability to store good extract in the condition of the room. The water content of each sample ranged from 3% - 9% with the lowest water content was in 85% concentration sample which was 3.62%, while the ash content ranged from 1.5% with the highest ash content which was in 85% concentration sample which was 1.59%. The results of characterization were identified by 3 compounds having the highest percentage of 2-Furaldehyde, Hexamethyl Cyclotriloxane, and 1,2,4-Trimethyl Benzene with the percentage of 26,94%, 9,95% and 13,82% respectively. 2-Furaldehyde includes heterocyclic aldehyde group sugars, whereas Hexamethyl Cyclotriloxane and 1,2,4-Trimethyl Benzene belong to the class of organosilicon and aromatic hydrocarbons. 2-Furaldehyde or Furfural serves as a tongue nerve stimulator and has great potential to be developed as an important non-petroleum-based chemical raw material. The GCMS results provide information that the obtained 2-Furaldehyde has a molecular formula C5H4O2 or C4H3OCHO which is a monosaccharide group which is aldose with the number of C atoms classified as pentose. The retention time was 3.062 minutes with a mass peak of 300 m/z with molecular weight was 96 g/mol.

Synthesis of pharmacophores containing a prolinate core using a multicomponent 1,3-dipolar cycloaddition of azomethine ylides

A multicomponent 1,3-dipolar cycloaddition between heterocyclic aldehydes, amino esters and dipolarophiles is efficiently promoted by silver acetate as catalyst, and depending on the nature of the heterocycle and its reactivity the reaction requires 70 °C or rt to complete. Selected pharmacophores anchored to a formyl group are chromone, 5-methoxyindole, pyridoxal surrogates and a very attractive uracyl derivative. The preference of each tested amino esters towards different dipolarophiles is discussed. At the end, a selective reduction of the ester group allows to obtain a very interesting dideoxiazanucleoside derivative.

СИНТЕЗ ТА ДОСЛІДЖЕННЯ АНТИТРИПАНОСОМНОЇ АКТИВНОСТІ НОВИХ 5-ІЛІДЕН-2-(1,3,4-ТІАДІАЗОЛ-2-ІЛ)ІМІНОТІАЗОЛІДИН-4-ОНІВ

Мета роботи. На основі реакцій гетероциклізації та Кньовенагеля здійснити синтез нових тіадіазоло-2-імінотіазолідин-4-онів та їх 5-ариліденпохідних для скринінгу антитрипаносомної активності.Матеріали і методи. Органічний синтез, спектроскопія ЯМР, елементний аналіз, фармакологічний скринінг.Результати й обговорення. Циклізацією N-(1,3,4-тіадіазол-2-іл)заміщених 2-хлороацетамідів під дією амонію тіоціанату в середовищі ацетону синтезовано серію нових похідних 2-імінотіазолідин-4-ону. Наявність метиленактивної групи в положенні 5 тіазолідинового циклу отриманих 2-(1,3,4-тіадіазол-2-іл)імінотіазолідин-4-онів дозволила провести їх подальшу модифікацію в умовах реакції Кньовенагеля з різноманітними арил(гетерил)карбальдегідами, ізатином або похідними коричного альдегіду з утворенням серій відповідних 5-арил(гетерил)іліден- та 5-ізатин(3-фенілпропен)іліденпохідних як потенційних антитрипаносомних агентів. Структуру синтезованих сполук підтверджено елементним аналізом та спектроскопією ПМР.Висновки. Результати скринінгу антитрипаносомної активності in vitro синтезованих сполук на штамі Trypanosoma brucei gambiense (TBG) дозволили ідентифікувати чотири високоактивні сполуки, які зі значеннями IC50 в межах 7,3-12,8 мкМ володіли суттєвим трипаноцидним ефектом.

Concise and efficient synthesis of E-stereoisomers of exo-cyclic carbohydrate enones. Aldol condensation of dihydrolevoglucosenone with five-membered aromatic aldehydes Part 1

Stereoselective synthesis of exocyclic enones 10–17 via a base-catalyzed direct aldol condensation between dihydrolevoglucosenone 1 and heterocyclic aldehydes 2–9 is described. The reaction is performed under mild conditions and is applicable to variety of heterocyclic aldehydes. E-Steroisomers of exo-cyclic enones are the only products. They are very easy to isolate and were formed in good to excellent (72–88%) yield. 1H NMR, 13C NMR analyses provide the structural assignment and absolute stereochemistry of the condensation products. Single-crystal X-ray diffraction of condensation product 12, additionally supports the structural assignment.

The synthesis, physico-chemical properties, the antibacterial and antifungal activity of 2-[(5-(adamantane-1-yl)-4-methyl-4H-1,2,4-triazole-3-yl)thio]acetohydrazide ylidene derivatives

One of the main stages for creating a drug is the synthesis of a promising substance. The combination of adamantane and 1,2,4-triazole in one molecule provides the fertile ground for the synthesis of new compounds with low toxicity and a pronounced pharmacological activity. Aim . To synthesize 2-[(5-(adamantane-1-yl)-4-methyl-4H-1,2,4-triazole-3-yl)thio]acetohydrazide ylidene derivatives, study their physico-chemical properties, the antimicrobial and antifungal activity. Results and discussion . During the synthetic part of our work the aldehyde selection was based on the presence of various substitutes in the aromatic or heterocyclic nuclei. Benzaldehyde and its fluorine-, bromine-, hydroxy-, nitro-, methoxy-, dimethylamino- and dimethoxy- substituents were used. Furan-2-carbaldehyde, 5-nitrofuran-2-carbaldehyde, pyridine-2-ylcarbaldehyde and pyridine-3-ylcarbaldehyde were used among heterocyclic aldehydes. The structure of the synthesized compounds was confirmed by modern complex physico-chemical methods of analysis, elemental analysis, IR, NMR 1H-spectroscopy, and their individuality was proven by HPLC-MS. In the course of the initial screening of the antimicrobial activity of the ylidene derivatives of 2-[(5-(adamantane-1-yl)-4-methyl-4H-1,2,4-triazole-3-yl)thio]acetohydrazide synthesized it was found that the compounds obtained revealed a moderate antimicrobial and antifungal activity. Experimental part . Ylidene derivatives of 2-[(5-(adamantane-1-yl)-4-methyl-4H-1,2,4-triazole-3-yl)thio]acetohydrazide were obtained by the reaction of nucleophilic addition of the hydrazide fragment of the aldehyde group carbonyl. The antimicrobial and antifungal activities were determined by serial two-fold dilution in the liquid nutrient media. To compare the antimicrobial activity of the compounds studied trimethoprim was used as a reference drug. Conclusions . New ylidene derivatives of 2-[(5-(adamantane-1-yl)-4-methyl-4H-1,2,4-triazole-3-yl)thio]acetohydrazide have been synthesized; their structure has been determined by modern physico-chemical methods of analysis (elemental analysis, IR- and NMR 1H-spectroscopy), and their individuality has been confirmed by HPLC-MS. Among the compounds synthesized the substances with the antimicrobial and antifungal action that is similar or in some cases even exceed the action of the reference drug trimethoprim have been found. The compound 2-[(5-(adamantan-1-yl)-4-methyl-4H-1,2,4-triazole-3-yl)thio]-N’-(4-hydroxybenzyliden)acetohydrazide appeared to be more active than the reference drug in relation to E. coli and S. aureus .

Poly(vinylpyrrolidone)-Grafted Silica as Polymeric Cosolvent Catalyst for Chemoselective Reduction of Aldehydes and Ketones to Alcohols

Poly(vinylpyrrolidone)-grafted silica as a polymeric cosolvent catalyst was prepared. This heterogeneous catalyst is used for the chemoselective conversion of various aliphatic, aromatic and heterocyclic aldehydes and ketones to their corresponding alcohols with sodium borohydride in high yields and short reaction times. This catalytic system reduces α, β-unsaturated aldehydes to produce allyl alcohols as an important synthetic precursors. The catalyst can be reused several times without any considerable decrease in its activity.

Synthesis and Antimicrobial Activity of Tricyclic Quinazolinethiones

Deoxyvasicine thione (III) and mackinazoline thione (6,7,8,9-tetrahydro-11H-pyrido[2,1-b]quinazoline-11-thione, IV) were synthesized and condensed with aromatic and heterocyclic aldehydes at the α-methylene [CH2-3 (III) or CH2-6 (IV)]. Either 3- and 6-arylidene derivatives (V – XIII) or 6-hydroxymethylaryl derivatives (XIV) were formed depending on the reaction conditions. Formylation of IV synthesized the 6-hydroxymethylidene derivative (XV). 6-Chloro-, -hydroseleno-, and -anilinomethylidenemackinazoline thiones (XVI – XIX) were also synthesized. The antimicrobial activity of the synthesized compounds against S. aureus, E. coli, Bacillus cereus, Candida albicans, and Pseudomonas aeruginosa was studied.

Transfer hydrogenation of aromatic and linear aldehydes catalyzed using Cp*Ir(pyridinesulfonamide)Cl complexes under base-free conditions

Cp*Ir(pyridinesulfonamide)Cl (Cp* = pentamethylcyclopentadienyl) precatalysts 1–7 are active for the transfer hydrogenation of aryl, alkyl, and heterocyclic aldehydes. Catalysis is conducted under base-free conditions in air without dried or degassed substrates and solvents. These reductions occur rapidly in moderate to high conversion (39–100%). Benzaldehyde derivatives are reduced to alcohols within 30 min at 85 °C using 1 mol% iridium precatalyst; reduction also occurs at lower temperatures and loadings (60 °C, 0.50 mol% precatalyst). Benzaldehyde derivatives that possess electron-rich and electron-poor substituents in the para position, including base-sensitive 4-hydroxybenzaldehyde, are readily reduced. Aryl aldehydes containing electron-poor groups are reduced faster than substrates possessing electron-rich moieties. Reduction of the positional isomers of methoxybenzaldehyde and isopropylbenzaldehyde shows highest reduction for the ortho isomer, followed by the meta isomer. Heterocyclic substrates, including biomass derived 5-hydroxymethylfurfural and 2-furfural, were reduced selectively to the alcohol. Decyl aldehyde was reduced to the linear alcohol; importantly self-condensation was not observed. Competition studies demonstrated selective reduction of aldehydes over ketones and a mercury poisoning experiment supports a homogeneous catalyzed pathway.

Chiral Brønsted Acid‐Catalyzed Asymmetric Synthesis of N‐Aryl‐cis‐aziridine Carboxylate Esters

AbstractWe report a multi‐component asymmetric Brønsted acid‐catalyzed aza‐Darzens reaction which is not limited to specific aromatic or heterocyclic aldehydes. Incorporating alkyl diazoacetates and, important for high ee's, ortho‐tert‐butoxyaniline our optimized reaction (i.e. solvent, temperature and catalyst study) affords excellent yields (61–98 %) and mostly >90 % optically active cis‐aziridines. (+)‐Chloramphenicol was generated in 4 steps from commercial starting materials. A tentative mechanism is outlined.