The Photochemistry of Diazomethane the Reactions of Methylene with Toluene and P-Xylene in Liquid Phase (I)

The photochemistry of diazomethane in toluene and p-xylene solutions was investigated. The reactions of methylene with toluene gave eight products. In the diazomethane p-xylene solution, p-ethyltoluene, 1,2,4-trimethylbenzene, 1,4-dimethylcyclohepatriene-1,3,5 and three unidentified compounds were found as products of the reaction of methylene with p-xylene. The relative rates of addition and insertion reaction of methylene with toluene and p-xylene have been calculated.     

Synthesis and characterization of chelate polymers containing etheric diphenyl ring in the backbone: thermal,optical, electrochemical,and morphological properties

A novel Schiff base, 4‐bromo‐2‐[(2‐[(5‐bromo‐2‐hydroxyphenyl)methylene]amino‐5‐nitrophenyl)iminomethyl]phenol (M1) was synthesized from the reaction of 5‐brom‐salicylaldehyde with 4‐nitro‐o‐phenylenediamine. Schiff base–metal complex was synthesized from the reaction of 4‐bromo‐2‐[(2‐[(5‐bromo‐2‐ hydroxyphenyl)methylene]amino‐5‐nitrophenyl)iminomethyl]phenol (M1) with copper (II) acetate monohydrate [(CH₃COO)₂ Cu · H₂O] salt. Poly‐ (M1‐Cu‐TDP) was synthesized from the reaction of M1‐Cu with 4,4′‐dithiodiphenol (TDP). Poly(M1‐Cu‐PDP) was synthesized from the reaction of M1‐Cu with 4,4′‐propane‐2,2‐diyldiphenol (PDP). Poly(M1‐Cu‐HDP) was synthesized from the reaction of M1‐Cu with 4,4′‐(1,1,1,3,3,3‐hexafluoropropane‐2,2‐di‐yl)diphenol (HDP). The structures of the synthesized monomer and chelate polymers were confirmed by FT‐IR, UV–Vis, ¹H‐ and ¹³C‐NMR, and elemental analysis. The characterization was made by TGA‐DTA, DSC, size exclusion chromatography, cyclic voltammetry, and solubility tests. Also, surface morphologies of chelate polymers were investigated by scanning electron microscope. Copyright © 2009 John Wiley & Sons, Ltd.     

Decomposition of chemically activated dimethylcyclopropane molecules vibrationally excited to various extent

The photolyses of ketene (at 313 and 280 nm) and diazirine at 313 nm in the presence of cis-butene-2 were studied. Vibrational relaxation of chemically activated dimethylcyclopropane was shown to occur as a multistep process, and 17 ± 4 kJ mol^?1 was obtained for the average energy transferred per collision with butene-2 collider. Activated cis-dimethylcyclopropane is formed in the reaction of singlet methylene and cis-butene-2 with broad energy distribution which originates from the energy partitioning in the photolytic act. About 30% of the energy released in the photolysis of the methylene source is carried by singlet methylene as vibrational energy at the time of reaction, and this fraction was found to be practically independent of the radical source.     

Diethyl N,N-dimethylaminomethylenemalonate in the synthesis of fused heterocyclic systems

The reactions of diethyl N,N-dimethylaminomethylenemalonate ( 3 ) with N- and C- nucleophiles were studied. In the reaction of 3 with heterocyclic amines 4 , with the amino group attached at α-position in respect to the ring nitrogen atom, substitution of the dimethylamino group in 3 with the heterocyclic amino took place to give diethyl heteroarylaminomethylenemalonates 5 , which can cyclize into fused azino- 6 or azolopyrimidinones 7 . In the reaction of 3 with the compound with an active methylene group attached at α-position in regard to the ring nitrogen atom, such as pyridinylacetonitrile ( 8 ), ethyl pyridinyl- ( 9 ), and quinolinylacetate ( 10 ), fused quinolizines 11 and 12 , and benzo[c]quinolizine 13 were formed, respectively. Heterocyclic systems with an active or potentially active methylene group incorporated in the ring system, such as pyrazole 14 , pyrimidine 15 , and pyridine derivative 18 , gave with 3 fused pyranones 16, 17 , and 19 , and dihydroxynaphthalenes 22 and 23 naphtho[2,1-b]pyranones 24 and 25 .     

Synthesis of ladder polymers containing polydiacetylene backbones connected with methylene chains and their optical properties

The polymers consisting of polydiacetylene (PDA) backbones were obtained from the novel monomer derivatives, R CC CC R′ CC CC R [where R =  (CH₂)₄OCONHCH₂COOC₄H₉, R′ =  (CH₂)_n ; n = 2, 4, 8] [4BCMU4A(n)], in which linear methylene chain is sandwiched between two diacetylene moieties by solid-state 1,4-addition reaction. The polymerization process was investigated in detail by using spectroscopic techniques such as solid-state ¹³C-NMR, visible absorption, and IR absorption spectra. It was estimated that the polymerization of 4BCMU4A(8) and 4BCMU4A(4) takes place by two consecutive 1,4-addition reactions to form two PDA backbones, which constitute the two poles of the respective ladders. The bridging methylene chain length in the monomer was found to play a vital role as far as the polymerization process is concerned. Thus, the monomers with eight or four methylene units could form the ladder–PDAs by a two-step process, whereas the monomer containing two methylene units could only undergo one-step of 1,4-addition reaction. Further, it was found that the crystallinity of the polymers depends on the methylene chain length in the monomers, 4BCMU4A(8) being the most crystalline of all. These structural features strongly affect their absorption spectra. The third-order nonlinear optical susceptibilities (χ⁽³⁾) for these polymers were measured using third-harmonic generation method. The largest χ⁽³⁾ value obtained was 3.4 × 10⁻¹¹ esu for the poly[4BCMU4A(8)] thin film in resonant region. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 3537–3548, 1999     

Green approach for the synthesis of 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol 3‐yl)methylene)‐1H‐pyrazole‐5(4H)‐ones and their DNA Cleavage,antioxidant, and antimicrobial activities

3‐Methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones (5a‐i) was prepared by the condensation reaction of different 3‐formyl‐2‐phenylindole derivatives (2a‐i) and 3‐methyl‐1‐phenyl‐2‐pyrazoline‐5‐one in quantitative yield by applying various green synthetic methods as grinding, microwave irradiation using different catalysts under solvent‐free mild reaction conditions with high product yields. The structures of the synthesized compounds were characterized on the basis of elemental analysis, infrared, ¹HNMR, ¹³C NMR, and mass spectral data. The synthesized compounds were screened for free radical scavenging, antimicrobial, and DNA cleavage activities. Most of the tested compounds belonging to the 3‐methyl‐1‐phenyl‐4‐((2‐phenyl‐1H‐indol‐3‐yl)methylene)‐1H‐pyrazol‐5(4H)‐ones series exhibited promising activities.     

Synthesis and Antimicrobial Activity of Some Novel Hydrazide,Pyrazole, Triazine,Isoxazole, and Pyrimidine Derivatives

In continuation of our efforts to find a new class of antimicrobial agents, a series of pyrazole, 1,2,4‐triazine, isoxazole, pyrimidine, and other related products containing a hydrazide moiety were prepared via the reaction of 2‐cyano‐N‐((2‐methoxynaphthalen‐1‐yl)methylene) acetohydrazide ( 1 ) with appropriate chemical reagents. These compounds were evaluated for their antimicrobial activities, and also their minimum inhibitory concentration against most of test organisms was performed. Among the tested compounds 4 , 5 , 6 , and 16 displayed excellent antimicrobial activity. All the synthesized products were confirmed by elemental analysis, IR, ¹H‐NMR, ¹³C‐NMR, and mass spectral data.     

Heterocycles from Pyrazoloylhydroximoyl Chloride: Synthesis of Certain Quinoxaline,Benzothiadiazine, Benzoxadiazine,Quinazolinone, Imidazo[1,2-a]pyridine,Imidazo[1,2-a]pyrimidine,Isoxazole, Pyrazolo[3,4-d]pyridazine and Pyrrolidino[3,4-d]isoxazolin-4,6-dione Derivatives

3-Ethoxycarbonyl-5-methyl-1-(4-methylphenyl)-4-pyrazoloylhydroximoyl chloride (1) reacted with o-phenylenediamine, o-aminothiophenol, o-aminophenol and methyl anthranilate to afford 3-nitrosoquinoxaline, benzothiadiazine, benzoxadiazine, and 3-hydroxyquinazoline, respectively. Imidazo[1,2-a]pyridine, imidazo[1,2-a]pyrimidine and isoxazole derivatives were obtained via the reaction of 1 with 2-aminopyridine, 2-aminopyrimidine and the appropriate active methylene compounds, respectively. Pyrazolo[3,4-d]pyridazines, and pyrrolidino[3,4-d]isoxazolines derivatives were also synthesized. The structures of the newly synthesized compounds were established on the basis of spectral data and alternate synthesis whenever possible.     

Rapidly and Highly Yielded Synthesis of Pyrimidine,Dihydropyrimidinone, and Triazino[2,1‐b]quinazolin‐6‐ones Derivatives

The reaction of 4‐oxo‐3,4‐dihydroquinazolinyl‐2‐guanidine 1 with several active methylene compounds has revealed formation of the corresponding hydropyrimidine and dihydropyrimidnone (DHPMs) derivatives via cycloaddition reaction mechanism. Satisfactory results were obtained with good yields, short time, and simplicity in the experimental procedure. Reaction with ketones in DMF proceeded via (5+1) heterocyclization and resulted in the formation of 2‐amino‐4‐(het)aryl‐4,6‐dihydro‐1(3)(11)H‐[1,3,5]triazino[2,1‐b]quinazolin‐6‐ones 8 , 9 , 10 , 11 , 12 , 13 , respectively. All compounds have been characterized based on IR, ¹H‐NMR, and mass spectrum.     

DBU-Mediated Carboxylative Coupling of Primary Amines,Carbon Dioxide and Propargyl Chlorides

A carboxylative coupling reaction of various primary amine and 3‐phenyl‐2‐propynyl or 2‐nonynyl chloride in the presence of 8‐diazabicyclo[5.4.0]undec‐7‐ene (DBU) using carbon dioxide as carboxylative reagent was presented. This transition‐metal free reaction system shows broad substrate scope and gives a series of propargylcarbamates in moderate to good yield. The obtained N‐alkyl substituted carbamate product can undergo base‐catalyzed intramolecular cyclization reaction to afford functionalized 4‐methylene‐2‐oxazolidinone in good yield.     

Synthesen in der Pyridazin-Reihe, 10. Mitt.: Über einige Reaktionen mit Pyridazonyl-4-essigsäuren

Zusammenfassung Es wird über einige Reaktionen an der Methylen-Gruppe der Pyridazonyl-4-essigsäuren berichtet, so die Crotonisierung und die Reaktion nachJapp—Klingemann. Weiter wurden auch Hydrazide erhalten und aus diesen die entsprechenden substituierten 1,3,4-Oxdiazole hergestellt.

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Some reactions on the reactive methylene group of 4-carboxymethyl pyridazines are reported, e. g. the condensation with aldehydes and theJapp—Klingemann reaction. Furthermore, the corresponding hydrazides were prepared and these were used for the preparation of 1,3,4-oxadiazole derivatives.

     

Synthesis, reactions, and biological activity of 1,4-benzothiazine derivatives

Abstract  

6,7-Dimethoxy-2H-1,4-benzothiazin-3(4H)-one reacts with dimethylformamide dimethylacetal (DMF-DMA) to give the novel enaminone 2-(dimethylaminomethylene)-6,7-dimethoxy-2H-1,4-benzothiazin-3(4H)-one. The reaction of the latter with various active methylene compounds afforded pyrido[3,2-b][1,4]benzothiazines. Also, coupling of the enaminone with diazotized aniline derivatives gave 2-(arylhydrazono)-6,7-dimethoxy-2H-1,4-benzothiazin-3(4H)-ones. Spectral data indicated that the latter compounds exist predominantly in the hydrazone tautomeric form. In addition, coupling of the enaminone with diazotized heterocyclic amines afforded tetra- and pentaheterocyclic ring systems. The antitumor and antimicrobial activity of some of the synthesized compounds was screened.     

p-Hydroxybenzylierung von Carbanionen mit Chinonmethid-liefernden Verbindungen

p-Hydroxybenzylation of Carbanions with Quinonemethide Precursors. 3,5-Dialkylated 4-hydroxy-benzyl derivatives 4, 5 and 6 are useful starting materials for the p-hydroxybenzlation of carbanions derived from activated methylene compounds 7 . The reaction presumably proceeds through intermediate formation of quinonemethides 2 . The scope of the reaction is discussed.     

Synthesis,characterization, and dyeing performance of some azo thienopyridine and thienopyrimidine dyes based on wool and nylon

A string of novel heterocyclic mono azo dyes were synthesized and their utilization in dyeing different fabrics as wool and nylon were discussed. Thienopyridine azo dyes 4 and 6 were prepared by reaction of chloro acetamidederivative 2 with diamino compounds to yield 3 and 5 , followed by reaction with NaNO₂/HCl and coupling with nucleophilic reagent. One-pot reaction of chloro acetamide 2 with ammonium thiocyanat in solvent ethanol gave the unexpected thienopyrimidine derivative 7 , which contain two active sites, the former is primary amine that was able to form diazonium salt that coupled with N,N-dimethylaniline, resorcinol, and/or self-coupling to afford the azo dyes 8-10 , and the latter is active methylene group that underwent coupling with different diazonium salts to give the azo thienopyrimidine derivative dye 11-15 . The dyeing performance of these azo dyes had been investigated in terms of their dyeing behavior and fastness properties on different fabrics. Results showed that the color strength (K/S) values, as well as, washing, rubbing, and resistance to acid, alkali and light showed high efficiency of these heterocyclic mono azo dyes to dye wool rather than nylon fibers.     

DFT Study on the Origin of the Enantioselectivity of （S）-4-Hydroxylproline-Catalyzed Direct Aldol Reaction between Acetone and 4-Nitrobenzaldehyde

DFT-B3LYP calculations were carried out to study the enantioselectivity of the （S）-4-hydroxylproline-catalyzed direct aldol reaction between acetone and 4-nitrobenzaldehyde. Four transition structures associated with the stereo-controlling step of the reaction have been determined. They are corresponding to the anti and syn arrangements of the methylene moiety related to the carboxylic acid group in enamine intermediate and the si and re attacks to the aldehyde carbonyl carbon. The effect of DMSO solvent on the stereo-controlling step was investigated with polarized continuum model （PCM）. The computed energies of the transition states reveal the moderate enantioselectivity of the reaction.     

Simple,Efficient, and Green Method for Synthesis of Trisubstituted Electrophilic Alkenes Using Lipase as a Biocatalyst

A simple and efficient Knoevenagel condensation method for the synthesis of trisubstituted electrophilic alkenes was developed using lipase as a biocatalyst. Knoevenagel condensation was performed using the conventional method and using lipases (Aspergillus oryzae or Rhizopus oryzae) as biocatalysts, and reaction time, reaction temperature, yield, and recyclability were compared. Using a lipase as a biocatalyst eliminated the need for bases such as piperidine and pyridine. A wide range of aromatic aldehydes and ketones readily undergo condensation with active methylene compounds. The workup procedure is also very simple, and yields of the reactions are in the range of 75% to 95%. Both the biocatalysts were effectively recycled four times with no major decrease in the yield of product. The remarkable catalytic activity and reusability of lipase widens its applicability in Knoevenagel condensation with good to excellent yields for synthesis of trisubstituted electrophilic alkenes.     

Activated nitriles in heterocyclic synthesis. A novel synthesis of 1,2,4-tnazol-3-oyl nitriles

Synthesis of 1,2,4-triazoloyl nitriles via reaction of 4-phenylhydrazono-2-phenyl-2-oxazolin-5-one and 4-phenylhydrazono-2-ethoxy-2-thiazolin-5-one with active methylene nitriles was accomplished. Some of the chemical properties of the nitriles obtained are reported.     

Syntheses of Hitherto Unknown Thiazole,Ylidene and Pyridinethione Derivatives Having a Piperidin‐1‐yl Moiety and Their Use as Antimicrobial Agents

The novel hydrazone derivatives 2a‐c were prepared by treatment of aldehydes 1a,b with some hydrazines. Thiocarbamoyl functional group in compound 2a was subjected to cyclization reactions with some α‐halocarbonyl reagents and furnished the novel thiazoles 4‐6 , 8 and 9 . Enaminonitrile 10 and pyridinone 13 derivatives were synthesized by interaction of active methylene compound 2b with N,N‐dimethylformamide‐dimethylacetal and ketene dithioacetal 11 , respectively. Aliphatic, aromatic and heteroaromatic active methylene compounds were condensed with aldehydes 1a,b to afford the new ylidenes 15a‐d , 19a,b , 20 and 21 . Substituted pyridinethiones 22 and 23 were prepared in high yields by cyclocondensation of 15c with malononitrile and ethyl cyanoacetate, respectively. Indeno[1,2‐b]pyridines 26a,b were obtained by the reaction of ylidenes 19a,b with cyanothioacetamide in ethanol and in the presence of sodium ethoxide under reflux. The structures of the synthesized compounds were established from their analytical and spectral data. The prepared compounds were also screened for their antimicrobial activity.     

Bis‐dihydropyrimidines: Catalyst‐free,Microwave‐assisted Organic Synthesis,Characterization and In Vitro Biological Screenings

In present research, we aim to afford the catalyst‐free, greener synthesis of diethyl 2,2′‐(1,2‐phenylenebis(methylene))bis(sulfanediyl)bis(6‐methyl‐4‐substitutedphenyl‐1,4‐dihydropyrimidine‐5‐carboxylate)derivatives via microwave irradiations. The reactions were also performed under conventional heating. The reaction times and yields thus obtained of the isolated desired products were compared too, and hence explaining the significance of using microwave irradiations. The structural elucidation of the synthesized moieties was carried out by modern sophisticated spectral techniques. The prepared bis‐heterocycles were screened for their in vitro anti‐microbial activities. Samples that possessed electron‐releasing group on the phenyl ring showed anti‐bacterial activities while those that carry electron‐withdrawing group exhibited anti‐fungal activities.     

Reactions of O-methyl o-quinone monoximes with methyl-, methylene- and methine- substituted aromatic compounds. Synthesis of benzo[d]oxazole and 1,4-benzoxazine derivatives

O-Methyl o-quinone monoxime 1 reacts thermally with compounds 2a-d or 6a,b or 7a,b to give mainly the corresponding 2-substituted phenanthroxazoles 3a-c and 8 . The reaction of 1 with aromatic methylene compounds lOa-c affords the ketones 13a-c in moderate to high yields. Similar products are also obtained from the reaction of monoximes 15a,b with some of the above reactants. The unexpected products 5 and 20 are obtained from the reaction of 1 with 2-methylimidazole ( 2d ) and with phenyloxirane ( 19 ) respectively, while the 4H-1,4-oxazine derivative 23 is obtained from the reaction of 1 with indene ( 21 ).