Synthesis of 2-arylamino substituted 5,6-dihydropyrido[2,3-d]pyrimidine-7(8H)-ones from arylguanidines

A practical protocol was developed for the synthesis of 2-arylamino substituted 4-amino-5,6-dihydropyrido[2,3-d]pyrimidin-7(8H)-ones from ??,??-unsaturated esters, malononitrile, and an aryl substituted guanidine via the corresponding 3-aryl-3,4,5,6- tetrahydropyrido[2,3-d]pyrimidin-7(8H)-ones. Such compounds are formed upon treatment of 2-methoxy-6-oxo-1,4,5,6-tetrahydropyridine-3-carbonitriles with an aryl substituted guanidine in 1,4-dioxane and are converted to the desired 4-aminopyridopyrimidines with NaOMe/MeOH through a Dimroth rearrangement. The overall yields of this three-step protocol are, generally speaking, higher than the multicomponent reaction, previously developed by our group, between an ??,??-unsaturated ester, malononitrile, and an aryl substituted guanidine.     

A new one-pot three-component synthesis of 2,4-diamino-5<Emphasis Type="Italic">H</Emphasis>-chromeno[2,3-<Emphasis Type="Italic">b</Emphasis>]pyridine-3-carbonitrile derivatives

In this study, a three-component one-pot synthesis of new 2,4-diamino-5H-chromeno[2,3-b]pyridine-3-carbonitriles derived from 2-amino-1,1,3-tricyanopropene, salicylic aldehydes and secondary cyclic amines is reported. The reaction is conducted in ethanol at ambient temperature in good-to-excellent yields.     

Organic synthesis in water: a green protocol for the synthesis of 2-(cyclohexylamino)-3- aryl- indeno[1,2-b]furan-4-ones

Aldehydes, 1,3-indandione and cyclohexylisocyanide undergo smooth coupling-cyclization in water to produce the corresponding 2-(cyclohexylamino)-3-aryl- indeno [1,2-b] furan-4-ones in good yields. Water was used as a solvent to avoid the use of other highly toxic and environmentally unfavorable solvents for this synthesis.

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Graphical Abstract  A simple and efficient synthesis of 2-(cyclohexylamino)-3-aryl- indeno[1,2-b]furan-4-ones was achieved via a one-pot three-component reaction of cyclohexylisocyanide, aldehydes, and 1,3-indandione in water for 5 h in good yields. zFX

     

An efficient synthesis of substituted 2-iminothiazolidin-4-one and thiadiazoloquinazolinone derivatives

A convenient synthesis of functionalized 2-iminothiazolidin-4-ones and thiadiazoloquinazolinones has been achieved by the reaction of dialkyl acetylenedicarboxylates (DAAD) with 1-pheny-3-pyridin-2-yl-thiourea (1) and 3-amino-2-mercapto-3H-quinazolin-4-one (8), respectively. The starting materials for these processes were prepared from phenyl isothiocyanate, 2-aminopyridine for (1) and anthranilic acid, carbon disulfide, hydrazine for (8). Treatment of these compounds with DAAD resulted in the formation of an intermediate that readily underwent intramolecular cyclization to afford functionalized five membered heterocyclic rings was formed.     

Ultrasound promoted selective synthesis of 2-aryl-5,6-dihydro-4H-1,3-oxazines catalyzed by K-10 and KSF montmorillonite clays: A practical procedure under mild and solvent-free conditions

Montmorillonite K-10 and KSF were found to be highly efficient, environmentally friendly and recyclable heterogeneous catalysts for the selective synthesis of a variety of 2-aryl-5,6-dihydro-4H-1,3-oxazines from arylnitriles and 3-amino-1-propanol under ultrasound irradiation. This new methodology provides excellent yields in short reaction times (10–25 min). The reaction work-up is very simple and the catalysts can be easily separated from the reaction mixture and reused several times in subsequent reactions. This catalytic system also exhibits excellent chemoselectivity in the synthesis of mono-oxazines from dinitriles.     

Parallel synthesis of 1,2,4-triazole derivatives using microwave and continuous-flow techniques

Abstract  

An efficient and convenient solution-phase synthesis of a 1H-1,2,4-triazole library with potential agrochemical activity is reported employing microwave-assisted organic synthesis (MAOS) and continuous-flow microfluidic synthetic methods starting from commercially available 3,5-dibromo-1H-1,2,4-triazole (1). MAOS was used for the synthesis of 5-amino-3-bromo-1,2,4-triazole analogs 3 and for their 3-aryl derivatives 4 via Suzuki–Miyaura coupling with polymer-supported catalyst. A microfluidic hydrogenation reactor integrated into an automated parallel synthesis platform was built and utilized for the reductive dehalogenation reactions providing 5-aminotriazoles (5).     

Synthesis of functionalized 1,2,4-triazole-3-thiones from ammonium isothiocyanate,acid chlorides,and arylhydrazines

An efficient synthesis of 1-aryl-5-aryl(alkyl)-1,2-dihydro-3H-1,2,4-triazole-3-thiones via reaction between ammonium thiocyanate, acid chlorides, and arylhydrazines is described.     

A novel three-component reaction for the synthesis of 3-aryl-4H-benzo [1,4] oxazin-2-amine

A high yielding and fast method for the synthesis of 3-aryl-4H-benzo [1,4] oxazin-2-amine via one-pot, three component reaction of an aromatic aldehyde, isocyanide and o-aminophenol using p-toluene sulfonic acid as a catalyst is described.     

Ionic liquid-promoted multi-component reaction: novel and efficient preparation of pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]pyridinone,pyrazolo[3,4-<Emphasis Type="Italic">b</Emphasis>]-quinolinone and their hybrids with pyrimidine nucleoside

The utilization of an ionic liquid, [bmim][BF₄] as both reaction medium and promoter for a multi-component reaction of aldehyde (1) and 5-amino-3-methyl-1-phenylpyrazole (2) with Meldrum acid (3) or dimedone (5) is studied. From this reaction, pyrazolo[3,4-b]pyridinone (4) and pyrazolo[3,4-b]quinolinone (6) derivatives were prepared in high yields. This novel procedure showed such advantages as environmentally benign nature, enhanced efficiency, simple operation process, and mild reaction conditions. As an application, the procedure was successfully used in the preparation of a set of pyrimidine nucleoside–pyrazolo[3,4-b]pyridine and pyrazolo[3,4-b]quinolinone hybrids with potential biological activities.     

A convenient ultrasound-promoted regioselective synthesis of fused polycyclic 4-aryl-3-methyl-4,7-dihydro-1H-pyrazolo[3,4-b]pyridines

Fused polycyclic 4-aryl-3-methyl-4,7-dihydro-1H-pyrazolo[3,4-b]pyridines were obtained in a three-component regioselective reaction of 5-amino-3-methyl-1H-pyrazole, 2H-indene-1,3-dione and arylaldehydes in ethanol under ultrasound irradiation. This rapid method produced the products in short reaction times (4–5 min) and excellent yields (88–97%).     

An unusual synthesis of 3-(2-(arylamino)thiazol-4-yl)-2H-chromen-2-ones from ethyl 2-(chloromethyl)-2-hydroxy-2H-chromene-3-carboxylate via benzopyran ring opening

An unusual and unexpected synthesis of 3-(2-(arylamino)thiazol-4-yl)-2H-chromen-2-ones has been observed by the reaction of ethyl 2-(chloromethyl)-2-hydroxy-2H-chromene-3-carboxylate with various arylthioureas in ethanol under mild reaction conditions with excellent yields. The ambiguity in the structure of the obtained products has been solved by recording its single-crystal X-ray analysis. This protocol has been found to be a novel approach for the preparation of title compounds via benzopyran ring opening. A systematic plausible mechanism has been proposed for the formation of the product. Also, an efficient one-pot three-component method has been demonstrated for the formation of title compounds starting from salicylaldehyde.

     

1H and 13C NMR Spectral Study of Some 2r-Aryl-6c-phenylthian-4-ones,Their 1-Oxides and 1,1-Dioxides

ABSTRACT

Four 2r-aryl-6c-phenylthian-4-ones 1b?1e and their 1-oxides 2b?2e and 1,1-dioxides 3b?3e have been newly synthesized. ¹H and ¹³C NMR spectra have been recorded for all these compounds and 2r,6c-diphenylthian-4-one 1-oxide 2a. ¹³C NMR spectrum has been recorded for the sulfone 3a of 1a. For selected compounds ¹H-¹H COSY, HSQC, HMBC, and NOESY spectra have been recorded. The vicinal proton–proton coupling constants suggest that in all these compounds, the heterocyclic ring adopts chair conformation with equatorial orientations of the aryl and phenyl groups. Proton and carbon chemical shifts suggest that in the sulfoxides, the S=O bond is axial and enhances the J _aa value by some special effect. The S = O bond causes a significant upfield shift even on carbons without hydrogens. Significant solvent shifts also were observed.     

Energetic ionic salts based on nitrogen-rich heterocycles: A prospective study

New energetic salts may be synthesized via the quarternization of azido or nitro derivatives of 1,2,4-triazole, and substituted derivatives of tetrazole with nitric acid or perchloric acid or iodomethane followed by metathesis reaction with AgNO₃ or AgClO₄ have been suggested in the literature for synthesis of new energetic ionic salts. The present review focuses briefly on the synthesis aspects and some of the physico-chemical properties of energetic materials of the class have been investigated. The structures of prospective energetic ionic salts include (a) 1-(2-azidoethyl)-1,2,4-triazolium-5-nitrotetrazolate, (b) 1-(2-azidoethyl)-3-azido-1,2,4-triazolium 5-nitrotetrazolate, (c) 1-(2-azidoethyl)-4-amino-1,2,4-triazolium perchlorate, 1-(2-azidoethyl)-1,2,4-triazole and so on. These compounds may find a wide spectrum of futuristic applications in the area of energetic materials. The salts exhibit good thermal stabilities, low vapour pressure, high heat of formation and high densities. Constant volume combustion energies may be determined experimentally using oxygen bomb calorimeter, DSC, ¹H and ¹³C NMR. The standard molar enthalpies of formation will be derived from designed Hess thermochemical cycles.     

Chemo- and stereoselective reaction between alkyl isocyanides and dimethyl 1,3-acetonedicarbocxylate in the presence of acetylenic esters

The reaction of alkyl isocyanides with dimethyl 1,3-acetonedicarboxylate in the presence of dialkyl acetylenedicarboxylates in CH₂Cl₂ at ambient temperature leads to highly functionalized 2-amino-4H-pyrans and 1,2-dialkyl 4,6-dimethyl-(1E, 3E)-3 (alkylamino)-5-oxo-1,3-hexadiene-1,2,4,6-tetracarboxylates.     

Ultrasound-assisted three-component synthesis of 3-(5-amino-1H-pyrazol-4-yl)-3-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-enyl)indolin-2-ones in water

Indium(III) chloride was found to be an efficient catalyst for the synthesis of 3-(5-amino-1H-pyrazol-4-yl)-3-(2-hydroxy-4,4-dimethyl-6-oxocyclohex-1-enyl)indolin-2-ones by one-pot, three-component reaction of dimedone, 1H-pyrazol-5-amines and isatins in water under ultrasonic irradiation. The advantages of this method are the use of a readily available catalyst, easy workup, excellent yields, and the use of water as a solvent that is considered to be relatively environmentally benign.     

X-ray diffraction analysis of the modulated structure of Bi2Sr2CaFe2O y

The modulated structure of the Bi₂Sr₂CaFe₂O _y compound isomorphous with the Bi₂Sr₂CaCu₂O _y phase was refined by the method of the full profile analysis on the basis of the powder X-ray diffraction data. The analysis was carried out in the superspace group ofN:Abmm: 1 – 11 using the parameters of the unit cell of the basic structurea = 5.466(3),b = 5.446(5) andc = 31.25(9) Å and the modulation vectorq = 0.220(5)b* +c*. The model of excess oxygen interstitials into the BiO plane was used by applying a saw-tooth-type function of the form:U = 2U ₀ [(X ₄ -X ₄ ⁰ /)] [1]. The results point to a strong displacement of the atoms from their positions in the basic structure. An essential improvement of theR factors was obtained by taking into account the modulation waves of the higher harmonics.     

Efficient synthesis of alkyl 2-[2-(arylcarbonylimino)-3-aryl-4-oxo-1, 3-thiazolan-5-ylidene]-acetates

Reaction of 1-aryl-3-arylcarbonylthioureas with dialkyl acetylenedicarboxylates in CH₂Cl₂ at room temperature leads to alkyl 2-[2-(arylcarbonylimino)-3-aryl-4-oxo-1,3-thiazolan-5-ylidene]-acetates in good yields.     

Efficient synthesis and free-radical scavenging capacity of new 2,4-substituted tetrahydroquinolines prepared via BiCl<Subscript>3</Subscript>-catalyzed three-component Povarov reaction,using <Emphasis Type="Italic">N</Emphasis>-vinylamides

Efficient synthesis of new structurally different 2-(het)aryl-4-amidyl-substituted tetrahydroquinolines 8–29 is reported. The synthesis based on BiCl₃-catalyzed three-component Povarov reaction between anilines, (het)aryl aldehydes and enamides offers a fast, safe, and cheap way for efficient tetrahydroquinoline libraries construction. Using N-vinylamides (N-vinylpyrrolidin-2-one and N-vinylacetamide) in this reaction, it was possible to obtain two series of different cis tetrahydroquinolines with antioxidant properties. Among 14 tested compounds, 7 tetrahydroquinolines revealed a prominent anti-radical capacity, equal or higher than that of the commercial antioxidants. Being the most active molecule, the N-[2-(α-furanyl)-6-methoxy-1,2,3,4-tetrahydroquinolin-4-yl] acetamide 21 was ca. 2.2-fold more potent than the well-known antioxidant, vitamin E (α-tocopherol).     

FTIR Spectral Study of Intramolecular Hydrogen Bonding in Thromboxane A2 Receptor Antagonist S-145 and Related Compounds. Part 4

Abstract

An N-methylated compound of S-145, (±)-(5Z)-7-[3-endo-[N-methyl)phenylsulphonyl)amino]bicyclo [2.2.1]hept-2-exo-yl]heptenoic acid 1, its chain analogue 12-[N-methyl(phenylsulphonyl)amino]dodecanoic acid 3, (±)-(5Z)-7-[3-endo-(benzoylamino)bicyclo[2.2.1]hept-2-exo-yl] heptenoic acid 5 and related compounds were synthesized in order to study the formation of a new class of intramolecular hydrogen bond IX (cis-CO₂H…O = Y). Their FTIR spectra were measured in dilute CCl₄ solution and subjected to curve analysis in order to separate overlapping absorption bands. For compounds 1,3 and 5, the intramolecular hydrogen bonds of the IX type involving 14-, 17- and 14-membered rings were found between a carboxyl group, which takes a cis-structure IV, and an oxygen atom of a sulphonyl or benzoylamino group, respectively. The C[dbnd]O stretching vibration bands of these carboxyl groups shifted to lower wavenumbers (ca. 19 cm^?1). The direction of these shifts was contrary to that found for α-keto and α-alkoxycarboxylic acids in which carboxyl groups take a trans-structure III due to the formation of intramolecular hydrogen bonds I and II, respectively.     

The Schiff Base Probe With J-aggregation Induced Emission for Selective Detection of Cu2+

Here, three Schiff bases 3a-c, differing by the substitutions (–H, –Cl, and –N(CH₃)₂) on the phenyl ring, have been designed and synthesized via the reaction of ortho-aminophenol with benzaldehyde, 2,4-dichlorobenzaldehyde and para-dimethylamine benzaldehyde in 1:1 molar ratio with favourable yields of 89–92%, respectively. Their structural characterizations were studied by FT-IR, NMR, MALDI-MS and elemental analysis. The fluorescence behaviours of compounds 3a and 3b exhibited a severe aggregation caused quenching (ACQ) effect in EtOH/water system. On the contrary, compound 3c had an obvious J-aggregation induced emission (AIE) feature in EtOH/water mixture (v/v?=?1:1), and exhibited excellent sensitivity and anti-interference towards Cu²⁺ with the limit of detection (LOD) of 1.35?×?10^–8 M. Job’s plot analysis and MS spectroscopic study revealed the 2:1 complexation of probe 3c and Cu²⁺. In addition, probe 3c was successfully applied to the determination of Cu²⁺ in real aqueous samples.