A novel dehydrogenation occurring during the synthesis of the new heterocyclic system 1H-pyrazolo[3,4-b][2,7]naphthyridin-8-one

1,3-Disubstituted-5-aminopyrazoles and N-alkyl-3-carbethoxy-4-piperidones condense in refluxing acetic acid to give 1,3,6-trisubstituted 4,5-dihydro-1H-pyrazolo[3,4-b][2,7]naphthyridin-8(6H)ones (a new heterocyclic system) with loss of one molecule of hydrogen.     

Boric Acid‐Catalyzed Direct Condensation of Carboxylic Acids with Benzene‐1,2‐diamine into Benzimidazoles

The applicability of boric acid catalysis for the direct condensation of carboxylic acids with benzene‐1,2‐diamine to give 2‐substituted benzimidazoles was investigated. It was found that catalytic amounts (5–10 mol‐%) of boric acid efficiently promote the cyclocondensation of aliphatic carboxylic acids in refluxing toluene. In addition, the relatively neutral conditions allow the use of acid‐sensitive substrates and give rise to specific transformations and selectivities that are not observed with some classical methods. Benzoic acids were found to be less reactive than aliphatic acids and thus require refluxing xylene for better efficiency. Phenylboronic acid was found to be inactive as a catalyst due to its rapid consumption by condensation with benzene‐1,2‐diamine to give a 2‐phenylbenzodiazaborole.     

Synthesis,Reactions, and Pharmacological Evaluations of Some Novel Pyridazolopyridiazine Candidates

Herein, we report the synthesis, characterization, and preliminary pharmacological activity of a new series of substituted pyrazolopyridazine derivatives. Compound 1 was reacted with ethoxymethylene malononitrile 2 in refluxing ethanol to give the corresponding compound 3 , which was treated with hydrazine hydrate or formamide to give pyrazolo[3,4‐c]pyrazole 4 and pyrazolo pyrimidine 5 derivatives, respectively. Also, compound 3 was reacted with NH₄SCN or carbon disulphide or ethyl acetoacetate to yield the corresponding pyrazolo derivatives 6 , 7 , 8 , respectively. Additionally, compound 3 was reacted with triethyl orthoformat in acetic anhydride to give 9 , which was treated with hydrazine hydrate to give hydrazino derivative 10 . The latter compound transformed into the pyrazolo[4,3‐e][1,2,4]triazolo[1,5‐c]‐pyrimidine 11 via refluxing with acetic anhydride. Finally, compound 9 was reacted with benzoic acid hydrazide or mercapto acetic acid to give compounds 12 and 13 , respectively. The latter compound was treated with refluxing ethanolic sodium ethoxide solution to afford the pyrazolothiazolopyrimidine 14 . Some of the compounds exhibited better activities as anti‐inflammatory and antimicrobial agents than the reference controls. The detailed synthesis, spectroscopic data, anti‐inflammatory, and antimicrobial activities of the synthesized compounds was reported.     

An efficient catalytic method for the synthesis of 2,7-dialkyl-2,3a,5a,7,8a,10a-hexaazaperhydropyrenes

An efficient method for the synthesis of 2,7-dialkyl-2,3a,5a,7,8a,10a-hexaazaperhydropyrenes in high yields (up to 95%) via the intermolecular cyclization of 1,4,5,8-tetraazadecalin with N,N-bis(methoxymethyl)-N-alkylamines in the presence of SmCl₃·6H₂O as the catalyst has been developed.     

A convenient synthesis and spectroscopic characterization of N, N'-Bis(2-propenyl)-2,7-diazapyrenium quaternary salts

N,N'-Bis(2-propenyl)-2,7-diazapyrenium salts are synthesized in good yield from the reaction of 1,4,5,8-naphthalenetetracarboxylic dianhydride with allylamine, followed by LiAlH(4) reduction and subsequent oxidation with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). The nature of the counteranion depends on the solvent system used for recrystallization of the crude product from the final DDQ-oxidation step. X-ray analysis shows that if recrystallization is carried out in boiling CH(3)OH/H(2)O (1:1, v/v), the counteranion in the resulting deep-red crystals is always the alkoxy anion of 2-cyano-5,6-dichloro-3-hydroxy-1,4-benzoquinone, whether the final DDQ oxidation ends with addition of HClO(4) or HCl; on the other hand, if recrystallization is carried out with anhydrous acetonitrile, the product is N,N'-bis(2-propenyl)-2,7-diazapyrenium diperchlorate or dichloride depending on whether the DDQ oxidation is followed by addition of concd HClO(4) or concd HCl, respectively. Importantly, if the DDQ oxidation is quenched with HBr, Br(-) is oxidized to Br(2) by unreacted DDQ, and the resulting product is N, N'-bis(2,3-dibromopropyl)-2,7-diazapyrenium dibromide. Comparative absorption and time-resolved emission studies provide evidence for possible dimerization of N,N'-bis(2-propenyl)-2,7-diazapyrenium diperchlorate in CH(3)CN.     

Rearrangements of 4-(2-Aminophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylic acid diethyl ester

The treatment of 4-(2-aminophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinecarboxylic acid diethyl ester (III) with refluxing toluene or pyridine afforded 1,2,3,6-tetrahydro-2,4-dimethyl-2,6-methano-1,3-benzodiazocine-5,11-dicarboxylic acid diethyl ester (IV) as the major product. In addition, the following minor products were isolated: 2-methyl-3-quinolinecarboxylic acid ethyl ester (V), 3-(2-aminophenyl)-5-methyl-6-azabicyclo[3,3,1]-hept-1-ene-2,4-dicarboxylic acid diethyl ester (VI), and 5,6-dihydro-2,4-dimethyl-5-oxobenzo[c][2,7]naphthyridine-1-carboxylic acid ethyl ester (VII). In contrast, acidic conditions caused the conversion of III into V in a 95% yield. The formation of the latter appears to involve IV as an intermediate, since IV degraded rapidly in acid to give V in a quantitative yield.     

Rapid determination of the optical and redox properties of a metal-organic framework via in situ solid state spectroelectrochemistry

The optical properties of [Zn(2)(NDC)(2)(DPNI)](0/-/2-) (NDC = 2,7-naphthalene dicarboxylate, DPNI = N,N'-di(4-pyridyl)-1,4,5,8-naphthalenetetracarboxydiimide), a redox-active metal-organic framework, have been examined using a simple and robust in situ solid state UV-Vis-NIR spectroelectrochemical technique.     

Efficient Catalytic Synthesis of 2,7-Diaryl(hetaryl)-4,9-dimethylperhydro- 2,3a,5a,7,8a,10a-hexaazapyrenes

A one-pot procedure has been developed for the synthesis of 2,7-diaryl(hetaryl)-4,9-dimethylperhydro- 2,3a,5a,7,8a,10a-hexaazapyrenes by cyclocondensation of aren(hetaren)amines with formaldehyde and 2,6-dimethyl-1,4,5,8-tetraazadecalin in the presence of YbCl₃ · 6 H₂O as catalyst.     

Optimized domain size and enlarged D/A interface by tuning intermolecular interaction in all‐polymer ternary solar cells

The selection of sensitizer and its existence in the blend films are important to the performance of all‐polymer ternary solar cells. Herein, all‐polymer ternary solar cell devices, which used poly[4,8‐bis(5‐(2‐ethylhexyl)thiophen‐2‐yl)benzo[1,2‐b:4,5‐b′] dithiophene‐alt‐3‐fluorothieno[3,4‐b]thiophene‐2‐carboxy‐late] (PTB7‐Th) as donor, poly[[N,N‐bis(2‐octyldodecyl)‐napthalene‐1,4,5,8‐bis(dicarboximide)?2,6‐diyl]‐alt‐5, 5′‐(2,2′‐bithiophene)] (N2200) as acceptor and poly[N?900‐hepta‐decanyl‐2,7‐carbazole‐alt‐5,5‐(40,70‐di‐2‐thienyl‐20,10,30‐benzothiadiazole) (PCDTBT) as sensitizer, are successfully demonstrated. The intermolecular interaction between donor PTB7‐Th and sensitizer PCDTBT may lead to aggregation of PTB7‐Th which decreases domain sizes and enlarges D/A effective interface area. In addition, the PCDTBT molecules also extend light absorption and cascaded energy levels of the ternary blend system. As a result, with 15% PCDTBT we get a power conversion efficiency of 5.11%, almost 20% higher than control device due to more favored exciton dissociation and higher charge transport efficiency. This study reveals a promising way to achieve high efficiency all‐polymer solar cells using a low‐band gap polymer PCDTBT. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1811–1819     

Simple synthesis,photophysics, and electroluminescent properties of poly[2,7‐bis(4‐tert‐butylstyryl)fluorene‐9, 9‐diyl‐alt‐alkane‐α,ω‐diyl]

A simple synthetic route was used for the synthesis of a novel series of alternating copolymers based on substituted 2,7‐distyrylfluorene bridged through alkylene chains. First, 2,7‐dibromofluorene was reacted with 2 equiv of butyllithium, and this was followed by a treatment with 1 equiv of α,ω‐dibromoalkane to yield the intermediate, poly(2,7‐dibromofluorene‐9,9‐diyl‐alt‐alkane‐α,ω‐diyl). ( 1 ) Heck coupling of the latter with 1‐tert‐butyl‐4‐vinylbenzene afforded the target, poly[2,7‐bis(4‐tert‐butylstyryl)fluorene‐9,9‐diyl‐alt‐alkane‐α,ω‐diyl] ( 2 ). The two versions of 2 ( 2a and 2b which have hexane and decane, respectively, as alkane groups) were readily soluble in common organic solvents. Their glass‐transition temperature was relatively low (52 and 87 °C). An intense blue photoluminescence emission with maxima at about 408 and 409 nm was observed in tetrahydrofuran solutions, whereas thin films exhibited an orange emission with maxima at 569 and 588 nm. Very large redshifts of the photoluminescence maxima and Stokes shifts in thin films indicated strong aggregation in the solid state. Both polymers oxidized and reduced irreversibly. Single‐layer light‐emitting diodes with hole‐injecting indium tin oxide and electron‐injecting aluminum electrodes were fabricated. They emitted orange light with external electroluminescence efficiencies of 0.52 and 0.36% photon/electron, as determined in light‐emitting diodes made of 2a and 2b , with alkylenes of (CH₂)₆ and (CH₂)₁₀, respectively. An increase in the external electroluminescence efficiency up to 1.5% was reached in light‐emitting diodes made of polymer blends consisting of 2a and poly(9,9‐dihexadecylfluorene‐2,7‐diyl), which emitted blue‐white light. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 809–821, 2007.     

Novel tandem reaction of benzyne with cyclic ethers and active methines: synthesis of ω-trichloroalkyl phenyl ethers

The reaction of benzenediazonium carboxylate with chloroform in refluxing tetrahydrofuran afforded 5,5,5-trichloropentyl phenyl ether in 61% yield along with benzoic acid (7%). When dichloroacetonitrile was used as a reactant, 5,5-dichloro-5-cyanopentyl phenyl ether was obtained in 65% yield. Reactive benzyne derived from diazonium carboxylate initially reacted with THF to give a dipole intermediate, which further reacted with chloroform or dichloroacetonitrile to give ring opened products.     

1,ω‐Bis(4‐amino‐1,2,4‐triazole‐5(1H)‐thion‐3‐ylsulfanyl)alkanes: Versatile precursors for novel bis(S‐triazolo[3,4‐b][1,3,4]thiadiazines) as well as novel bis(macrocyclic schiff bases)

Two synthetic routes were attempted for the synthesis of the novel bis(5,6‐dihydro‐S‐triazolo[3,4‐b]thiadiazines) 12a,b and 14 . In the first route the bis(aminotriazoles) 4a,b were reacted with the appropriate α‐haloketones or α‐haloesters to give the corresponding bis(S‐triazolo[3,4‐b]thiadiazines) 11a‐d followed by reduction with NaBH₄. In the second route, the bis(Schiff bases) 13d were reacted with the appropriate α‐haloesters in refluxing DMF containing TEA to give the target compound 14 . Cyclocondensation of 4a,b with the appropriate bis(carbonyl) ethers 15a,b in refluxing acetic acid under high dilution conditions afforded the corresponding macrocyclic Schiff bases 16a‐c . The latter underwent alkylation with the appropriate halo compounds to give the corresponding alkylated derivatives 17a‐d .     

Cycloadducts of Furan with Arynes Generated from 2‐Bromo‐1,4,5,8‐tetramethoxynaphthalene and 2,6‐Dibromo‐1,4,5,8‐tetramethoxynaphthalene

The reaction of 2‐bromo‐1,4,5,8‐tetramethoxynaphthalene ( 7 ) with sodium amide (or LDA) in the presence of a large excess of furan gave the epoxy compound 9 . The similar reaction of 2,6‐dibromo‐1,4,5,8‐tetramethoxynaphthalene ( 8 ) afforded the diepoxy compound 10 . The crystal structure of antidiepoxide 10 was determined by an X‐ray crystallography.     

Pyrene and anthracene dicarboxylic acids as fluorescent brightening comonomers for polyester

Diacids of fused arenes have been prepared for use as covalently bound fluorescent optical brightening agents in condensation polymers. The monomers: dimethyl 1,6‐pyrene dicarboxylate, dimethyl 1,8‐pyrenedicarboxylate, dimethyl 2,7‐pyrenedicarboxylate, 1,8‐bis(2‐carboxybenzoyl)pyrene dimethyl ester, dimethyl 2,6‐anthracenedicarboxylate, dimethyl 2,7‐anthracenedicarboxylate and dimethyl 9,10‐anthracenedicarboxylate are copolymerized with poly(ethylene terephthalate) and their optical properties are assessed. All of the polymers give blue fluorescence, with the copolymer containing dimethyl 1,6‐pyrenedicarboxylate being the brightest. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 1291–1301, 2000     

Synthesis of some new substituted ethanone hydrazones containing 1H‐1,2,4‐triazole and thiazole

Three new thiosemicarbazones have been synthesized by condensation reaction of 2‐bromo‐1‐arylethanones with thiosemicarbazide, which reacted with various 2‐bromo‐1‐arylethanones in ethanol under refluxing to give a series of substituted ethanone hydrazone derivatives. Their structures were confirmed by elemental analysis, IR, ¹H NMR, and MS spectra.     

Conversion of Some 2(3H)‐Furanones into Pyrrolinotriazine and Oxazolopyrimidine Derivatives

2(3H)‐Furanones 1 were utilized for the construction of pyrrolinotriazine and oxazolopyrimidine derivatives 4 and 9 . Thus, 1 reacted with glycine in ethanol at 70°C to give the acids 2 , which were cyclized into the pyrrolin‐5‐one derivatives 3 by the action of HCl/AcOH. The later compounds 3 were also obtained by refluxing the furanones 1 with glycine in glacial AcOH for 10 h. The carboxy functionality in 3 was used for the construction of a triazinone ring by treatment with thionyl chloride followed by refluxing the acid chloride with hydrazine in ethanol. The conversion of the furanones 1 into the oxazolopyrimidine derivatives 9 involved the following steps: (i) ring opening of the lactone ring with hydrazine hydrate to give the acid hydrazides 5 , (ii) conversion of the hydrazides 5 into the corresponding acyl azides 6 by action of NaNO2/AcOH, (iv) base‐catalyzed decomposition of the azides in the presence of glycine, (v) ring closure of the urea derivatives 7 into the pyrimidine derivatives 8 , and finally (vi) condensing 8 with benzaldehyde in the presence of NaOAc/AcOH mixture.     

Synthesis and characterization of white‐light‐emitting polyfluorenes containing orange phosphorescent moieties in the side chain

Two orange phosphorescent iridium complex monomers, 9‐hexyl‐9‐(iridium (III)bis(2‐(4′‐fluorophenyl)‐4‐phenylquinoline‐N,C^2′)(tetradecanedionate‐11,13))‐2,7‐dibromofluorene (Br‐PIr) and 9‐hexyl‐9‐(iridium(III)bis(2‐(4′‐fluorophenyl)‐4‐methylquinoline‐N,C^2′)(tetradecanedionate‐11,13))‐2,7‐dibromofluorene (Br‐MIr), were successfully synthesized. The Suzuki polycondensation of 2,7‐bis(trimethylene boronate)‐9,9‐dioctylfluorene with 2,7‐dibromo‐9,9‐dioctylfluorene and Br‐PIr or Br‐MIr afforded two series of copolymers, PIrPFs and MIrPFs, in good yields, in which the concentrations of the phosphorescent moieties were kept small (0.5–3 mol % feed ratio) to realize incomplete energy transfer. The photoluminescence (PL) of the copolymers showed blue‐ and orange‐emission peaks. A white‐light‐emitting diode with a configuration of indium tin oxide/poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate)/PIr05PF (0.5 mol % feed ratio of Br‐PIr)/Ca/Al exhibited a luminous efficiency of 4.49 cd/A and a power efficiency of 2.35 lm/W at 6.0 V with Commission Internationale de L'Eclairage (CIE) coordinates of (0.46, 0.33). The CIE coordinates were improved to (0.34, 0.33) when copolymer MIr10PF (1.0 mol % feed ratio of Br‐MIr) was employed as the white‐emissive layer. The strong orange emission in the electroluminescence spectra in comparison with PL for these kinds of polymers was attributed to the additional contribution of charge trapping in the phosphorescent dopants. © 2007 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 45: 1746–1757, 2007     

The suzuki–heck polymerization as a tool for the straightforward obtainment of poly(fluorenylene‐vinylene) sensitizers for dye‐sensitized solar cells

This article describes the synthesis and properties of the first poly(arylene‐vinylene)‐based sensitizers for application in dye‐sensitized solar cells (DSSC). The polymers were prepared by the Suzuki–Heck copolymerization of potassium vinyltrifluoroborate (PVTB) with a mixture of dibromoaryl comonomers designed to obtain macromolecules able to bind onto the photoelectrode by means of carboxyphenylene units. The copolymerization reactions were carried out in the presence of an excess of PVTB to lower the molecular weights of the polymers, which were obtained as soluble materials. The polymers poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene] ( P1 ), poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene‐co‐(4,7‐benzothiadiazolylene)‐vinylene] ( P2 ), and poly[(9,9‐didodecyl‐2,7‐fluorenylene)‐vinylene‐co‐(carboxy‐2,5‐phenylene)‐vinylene‐co‐2,5‐thienylene‐vinylene] ( P3 ) were used in DSSC devices, obtaining conversion efficiencies up to 0.88% ( P3 ). © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Photoreaction of 1H‐azepine‐2,7‐dione in alkaline solution

Photolysis of 1H‐azepine‐2,7‐dione 2 proceeded with alkali as in the photoreaction of N‐alkylimide to give 7‐hydroxy‐1H‐azepine‐2‐one 13 .     

An effective and regioselective bromination of 1,4,5,8-naphthalenetetracarboxylic dianhydride using tribromoisocyanuric acid

A highly efficient and cost-effective reagent for the bromination of 1,4,5,8-naphthalenetetracarboxylic dianhydride under mild reaction conditions is reported. Bromination of 1,4,5,8-naphthalenetetracarboxylic dianhydride using tribromoisocyanuric acid (TBCA) in concentrated H₂SO₄ is very effective and regioselective. 1,4,5,8-Naphthalenetetracarboxylic dianhydride was brominated smoothly under optimized reaction conditions to give mono-, di- and tetra-brominated products in good to excellent yields using TBCA. As a proof of principle, the potential of this bromination methodology is demonstrated by converting brominated naphthalenetetracarboxylic dianhydrides into N-imide and core functionalized 1,4,5,8-napthalenetetracarboxylic diimides by treating with n-butylamine to yield corresponding mono-, di- and tetra-(n-butylamino)-naphthalene diimides in good yields in one-step reactions.