Nitropyridyl isocyanates in 1,3‐dipolar cycloaddition reactions

The reactivity of 3‐nitro‐4‐pyridyl isocyanate ( 7 ) and 5‐nitropyridin‐2‐yl isocyanate ( 9 ) in 1,3‐dipolar cycloaddition reactions with azides and pyridine N‐oxides has been investigated. 1,3‐Dipolar cycloaddition to trimethylsilylazide (TMSA) afforded the respective tetrazolinones, 1‐(3‐nitropyridin‐4‐yl)‐1H‐tetrazol‐5(4H)one ( 8 , 50 %) and 1‐(5‐nitropyridin‐2‐yl)‐1H‐tetrazol‐5(4H)one ( 11 , 64 %). Respectively, 1,3‐dipolar cycloaddition of nitropyridyl isocyanates 7 and 9 to 3,5‐dimethylpyridine N‐oxide ( 14 ), 3‐methylpyridine N‐oxide ( 21 ) and pyridine N‐oxide ( 22 ) gave the substituted amines, 3,5‐dimethyl‐N‐(3‐nitropyridin‐4‐yl)pyridin‐2‐amine ( 17 ), 3,5‐dimethyl‐N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 20 ), N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 24 ), 5‐methyl‐N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 23 ) and 3‐methyl‐N‐(5‐nitropyridin‐2‐yl)pyridin‐2‐amine ( 25 ) in 65 ‐ 80 % yield, obtained by cycloaddition, rearrangement and decarboxylation. The results demonstrate that the nitropyridyl isocyanates ( 7,9 ) readily undergo 1,3‐dipolar cyloaddition reactions similar to phenyl isocyanates.     

New Methods for the Synthesis of 3‐Amino‐6,7‐Dihydro‐5H‐Cyclopenta[c]Pyridine‐4‐Carbonitriles and Cyclopenta[d]Pyrazolo[3,4‐b]Pyridines via a Smiles‐type Rearrangement

By reaction with sodium ethoxide and as a function of their structures, 2‐[(1‐alkyl(aryl)‐4‐cyano‐6,7‐dihydro‐5H‐cyclopenta[c ]pyridin‐3‐yl)oxy]acetamides 11 gave 1‐amino‐5‐alkyl(aryl)‐7,8‐dihydro‐6H‐cyclopenta[d ]furo[2,3‐b ]pyridine‐2‐carboxamides 10 and/or 1‐alkyl(aryl)‐3‐amino‐6,7‐dihydro‐5H‐cyclopenta[c ]pyridine‐4‐carbonitriles 12 .     

Reaction of 2‐[(2‐aminoethyl)amino]ethanol with pyridine‐2‐carbaldehyde and complexation of the products with CuII and CdII along with docking studies

The reaction between 2‐[2‐(aminoethyl)amino]ethanol and pyridine‐2‐carbaldehyde in a 1:2 molar ratio affords a mixture containing 2‐({2‐[(pyridin‐2‐ylmethylidene)amino]ethyl}amino)ethanol (PMAE) and 2‐[2‐(pyridin‐2‐yl)oxazolidin‐3‐yl]‐N‐(pyridin‐2‐ylmethylidene)ethanamine (POPME). Treatment of this mixture with copper(II) chloride or cadmium(II) chloride gave trichlorido[(2‐hydroxyethyl)({2‐[(pyridin‐2‐ylmethylidene)amino]ethyl})azanium]copper(II) monohydrate, [Cu(C₁₀H₁₆N₃O)Cl₃]·H₂O or [Cu(HPMAE)Cl₃]·H₂O, 1 , and dichlorido{2‐[2‐(pyridin‐2‐yl)oxazolidin‐3‐yl]‐N‐(pyridin‐2‐ylmethylidene)ethanamine}cadmium(II), [CdCl₂(C₁₆H₁₈N₄O)] or [CdCl₂(POPME)], 2 , which were characterized by elemental analysis, FT–IR, Raman and ¹H NMR spectroscopy and single‐crystal X‐ray diffraction. PMAE is potentially a tetradentate N₃O‐donor ligand but coordinates to copper here as an N₂ donor. In the structure of 1 , the geometry around the Cu atom is distorted square pyramidal. In 2 , the Cd atom has a distorted octahedral geometry. In addition to the hydrogen bonds, there are π–π stacking interactions between the pyridine rings in the crystal packing of 1 and 2 . The ability of PMAE, POPME and 1 to interact with ten selected biomolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B‐DNA) was investigated by docking studies and compared with doxorubicin.     

Synthesis of some new Pyridine‐based Heterocyclic Compounds with Anticipated Antitumor Activity

A novel class of 5‐amino‐N′‐(1‐(pyridin‐4‐yl)ethylidene)‐1H‐pyrazole‐4‐carbohydrazides and 8‐(pyridin‐4‐yl)pyrido[2,3‐d][1,2,4]triazolo[4,3‐a]pyrimidin‐5(1H)‐ones was synthesized from reaction of 2‐cyano‐N′‐(1‐(pyridin‐4‐yl)ethylidene)‐acetohydrazide and 7‐(pyridin‐4‐yl)‐2‐thioxo‐2,3‐dihydropyrido[2,3‐d]pyrimidin‐4(1H)‐one with the appropriate hydrazonoyl halides. Moreover, 2‐cyano‐N′‐(1‐(pyridin‐4‐yl)‐ethylidene)‐acetohydrazide was used for the synthesis of 2‐cyano‐N′‐(1‐(pyridin‐4‐yl)ethylidene)‐acrylohydrazides and 2‐oxo‐2‐(2‐(1‐(pyridin‐4‐yl)ethylidene)‐hydrazinyl)‐acetohydrazonoyl cyanides. The structures of the newly prepared compounds were confirmed by both elemental and spectral analyses as well as by alternate synthesis. The anticancer activities of the prepared compounds were screened against the hepatocellular carcinoma (HepG2) cell line, and the results showed that most of the compounds exhibit considerable activities.     

Synthesis and cytotoxicity studies of achiral azaindole‐substituted titanocenes

From the reaction of 1‐methyl‐1 H‐pyr‐rolo[2,3‐b]pyridine ( 1a ),1‐(methoxymethyl)‐1 H‐pyrrolo[2,3‐b]pyridine ( 1b ), 1‐isopropyl‐1 H‐pyrrolo[2,3‐b]pyridine (1c ), and 1‐(4‐methoxybenzyl)‐1 H‐pyrrolo[2,3‐b]pyridine ( 1d ) under Vilsmeier–Haak conditions, the corresponding aldehydes in position 3 ( 2a–2d ) were synthesized. These aldehydes were transformed in the corresponding fulvenes ( 3a–3d ) by the Knoevenagel condensation and treated with Li[BEt₃H] to obtain the corresponding lithiated cyclopentadienide intermediates ( 3′a–3′d ). These intermediates were, finally transmetallated to titanium with TiCl₄ to yield the 7‐azaindol‐3‐yl‐substituted titanocenes bis {[(1‐methyl‐1‐H‐pyrrolo[2,3‐b]pyridin‐3‐yl)methyl] cyclopentadienyl} titanium(IV) dichloride ( 4a ), bis{[(1‐methoxymethyl‐1‐H‐pyrrolo[2,3‐b]pyridin‐3‐yl)methyl]cyclopentadienyl} titanium(IV)dichloride ( 4b ), bis{[(1‐Isopropyl‐1‐H‐pyrrolo[2,3‐b]pyridin‐3‐yl)methyl]cyclopentadienyl} titanium(IV) dichloride ( 4c ), and bis{[(4‐methoxybenzyl‐1‐H‐pyrrolo[2,3‐b]pyridin‐3‐yl)methyl]cyclopentadienyl} titanium(IV) dichloride ( 4d ). All the titanocenes had their cytotoxicity investigated through MTT‐based preliminary in vitro testing on the Caki‐1 cell lines to determinate their IC₅₀ values. Titanocenes 4a–4c were found to have IC₅₀ values of 120 ± 10, 83 ± 13, and 54 ± 12, µM respectively, whereas 4d showed no cytotoxic activity. © 2011 Wiley Periodicals, Inc. Heteroatom Chem 22:148–157, 2011; View this article online at wileyonlinelibrary.com . DOI 10.1002/hc.20668     

Synthesis of 2‐Thioxohydropyridine‐3‐Carbonitrile, 2‐Alkylthiopyridine,Thienopyridine, Pyrazolopyridine Derivatives and Their Theoretical Calculations

Cyanothioacetamide ( 1 ) reacted with but‐2‐enal ( 2 ) to give the corresponding 4‐methyl‐2‐sulfanylpyridine‐3‐carbonitrile ( 7 ) which was used as a good starting material for the synthesis of 1‐(3‐amino‐4‐methylthieno[2,3‐b]pyridin‐2‐yl)ethan‐1‐one ( 10 ), 3‐amino‐4‐methylthieno[2,3‐b]pyridine‐2‐carboxamide ( 15 ), 3‐amino‐4‐methylthieno[2,3‐b]pyridine‐2‐carboxylate ( 18 ) and 3‐amino‐4‐methylthieno[2,3‐b]pyridin‐2‐ylarylketone 25a‐c through its reactions with each of (1‐chloroacetone ( 8 ), 3‐chloropentane‐2,4‐dione ( 11 ) or ethyl 2‐chloro‐3‐oxo‐butanoate ( 19 )), 2‐chloroacetamide ( 13 ), ethyl 2‐chloroacetate ( 16 ) and 2‐bromo‐1‐arylethan‐ 1 ‐one 23a‐c , respectively. Considering the data of elemental analyses, IR, ¹HNMR, mass spectra and theoretical calculations, structures of the newly synthesized heterocyclic compounds were elucidated.     

Synthesis of some new azole,pyrimidine, pyran,and benzo/naphtho[b]furan derivatives incorporating thiazolo[3,2‐a]benzimidazole moiety

Reaction of E‐3‐(N,N‐dimethylamino)‐1‐(3‐methylthiazolo[3,2‐a]benzimidazol‐2‐yl)prop‐2‐en‐1‐one ( 1 ) with some N‐nucleophiles, such as anilines 2a , 2b , 2c , 4‐amino‐N‐pyridin‐2‐yl‐benzenesulfonamide ( 4a ), 4‐amino‐N‐pyrimidin‐2‐yl‐benzenesulfonamide ( 4b ), hydrazine, hydroxylamine, thiourea, and guanidine afforded the corresponding arylaminoprop‐2‐en‐1‐one derivatives 3a , 3b , 3c , 5a , 5b , the pyrazole, isoxazole, pyrimidinethione and aminopyrimidine derivatives 7a , 7b , 9a , and 9b , respectively. The utility of compound 1 , as a versatile building block, for the synthesis of the pyranone 13 , benzo[b]furan 17a , and naphtho[1,2‐b]furan 17b was also explored via its reaction with 2‐benzamidoacetic acid ( 10 ), 1,4‐benzoquinone ( 14a ), and 1,4‐naphthoquinone ( 14b ), respectively. J. Heterocyclic Chem., (2011).     

The effect of the coordination orientation of N atoms on polymeric structures: synthesis and characterization of one‐ and two‐dimensional CuII coordination polymers based on 4‐amino‐3‐(pyridin‐2‐yl)‐5‐[(pyridin‐3‐ylmethyl)sulfanyl]‐1,2,4‐triazole

Three new one‐ (1D) and two‐dimensional (2D) Cu^II coordination polymers, namely poly[[bis{μ₂‐4‐amino‐3‐(pyridin‐2‐yl)‐5‐[(pyridin‐3‐ylmethyl)sulfanyl]‐1,2,4‐triazole}copper(II)] bis(methanesulfonate) tetrahydrate], {[Cu(C₁₃H₁₂N₅S)₂](CH₃SO₃)₂·4H₂O}_n ( 1 ), catena‐poly[[copper(II)‐bis{μ₂‐4‐amino‐3‐(pyridin‐2‐yl)‐5‐[(pyridin‐4‐ylmethyl)sulfanyl]‐1,2,4‐triazole}] dinitrate methanol disolvate], {[Cu(C₁₃H₁₂N₅S)₂](NO₃)₂·2CH₃OH}_n ( 2 ), and catena‐poly[[copper(II)‐bis{μ₂‐4‐amino‐3‐(pyridin‐2‐yl)‐5‐[(pyridin‐4‐ylmethyl)sulfanyl]‐1,2,4‐triazole}] bis(perchlorate) monohydrate], {[Cu(C₁₃H₁₂N₅S)₂](ClO₄)₂·H₂O}_n ( 3 ), were obtained from 4‐amino‐3‐(pyridin‐2‐yl)‐5‐[(pyridin‐3‐ylmethyl)sulfanyl]‐1,2,4‐triazole with pyridin‐3‐yl terminal groups and from 4‐amino‐3‐(pyridin‐2‐yl)‐5‐[(pyridin‐4‐ylmethyl)sulfanyl]‐1,2,4‐triazole with pyridin‐4‐yl terminal groups. Compound 1 displays a 2D net‐like structure. The 2D layers are further linked through hydrogen bonds between methanesulfonate anions and amino groups on the framework and guest H₂O molecules in the lattice to form a three‐dimensional (3D) structure. Compound 2 and 3 exhibit 1D chain structures, in which the complicated hydrogen‐bonding interactions play an important role in the formation of the 3D network. These experimental results indicate that the coordination orientation of the heteroatoms on the ligands has a great influence on the polymeric structures. Moreover, the selection of different counter‐anions, together with the inclusion of different guest solvent molecules, would also have a great effect on the hydrogen‐bonding systems in the crystal structures.     

Synthetic studies connected with the preparation of h+/k+‐ATPase inhibitors rabeprazole and lansoprazole

Synthesis of lansoprazole and rabeprazole using common intermediates is devised. The common intermediates, 2‐[(4‐nitro‐3‐methylpyridin‐2‐yl)methanesulfanyl]‐1H‐benzoimidazole and 2‐[(4‐chloro‐3‐methyl‐pyridin‐2‐yl)methanesulfanyl]‐1H‐benzoimidazole, were prepared in several ways.     

Activated Anilide in Heterocyclic Synthesis: Synthesis of New Dihydropyridines,Dihydropyridazines and Thiourea Derivatives

A series of new dihydropyridines, butanamide, dihydropyridazines and thiourea derivatives have been prepared through the reactions of 3‐aminopyridine ( 1 ) and N‐(pyridin‐3‐yl)‐3‐(pyridin‐3‐ylimino)butanamide 3 with some electrophilic reagents, aryl diazonium salts and isothiocyanates. Elementary analysis, MS, IR, and ¹H NMR spectra confirmed the identity of the products.     

Detailed Studies of the Alkylation Sides of Pyridin‐2‐yl and 4,6‐Dimethylpyrimidin‐2‐yl‐cyanamides

Pyridin‐2‐yl‐ and 4,6‐dimethylpyrimidin‐2‐yl‐cyanamides entered into an alkylation reaction in the form of sodium salts. Pyridin‐2‐yl cyanamide 2 was alkylated at endo‐nitrogen atom of pyridine ring, while 4,6‐dimethylpyrimidin‐2‐yl cyanamide 1 was effectively alkylated at exo‐nitrogen atom of amino cyanamide group. The alkylation of cyanamides 1 and 2 with phenacylbromide gave the corresponding acetophenone derivatives. As a result of their intramolecular cyclization reactions 3‐(4,6‐dimethylpyrimidin‐2‐yl)‐5‐phenyloxazol‐2(3H )‐imine in the case of cyanamide 1 and 2‐amino‐3‐benzoylimidazo[1,2‐a ]pyridine in the case of cyanamide 2 were formed. The alkylated derivatives of pyridin‐2‐ylcyanamide 2 possess visible blue fluorescence with the main peak at 421 – 427 nm.     

Three AgI,CuI and CdII coordination polymers based on the new asymmetrical ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole: syntheses,characterization and emission properties

The new asymmetrical organic ligand 2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole ( L , C₁₇H₁₃N₅O), containing pyridine and imidazole terminal groups, as well as potential oxdiazole coordination sites, was designed and synthesized. The coordination chemistry of L with soft Ag^I, Cu^I and Cd^II metal ions was investigated and three new coordination polymers (CPs), namely, catena‐poly[[silver(I)‐μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole] hexafluoridophosphate], {[Ag( L )]PF₆}_n, catena‐poly[[copper(I)‐di‐μ‐iodido‐copper(I)‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)] 1,4‐dioxane monosolvate], {[Cu₂I₂( L )₂]·C₄H₈O₂}_n, and catena‐poly[[[dinitratocopper(II)]‐bis(μ‐2‐{4‐[(1H‐imidazol‐1‐yl)methyl]phenyl}‐5‐(pyridin‐4‐yl)‐1,3,4‐oxadiazole)]–methanol–water (1/1/0.65)], {[Cd( L )₂(NO₃)₂]·2CH₄O·0.65H₂O}_n, were obtained. The experimental results show that ligand L coordinates easily with linear Ag^I, tetrahedral Cu^I and octahedral Cd^II metal atoms to form one‐dimensional polymeric structures. The intermediate oxadiazole ring does not participate in the coordination interactions with the metal ions. In all three CPs, weak π–π interactions between the nearly coplanar pyridine, oxadiazole and benzene rings play an important role in the packing of the polymeric chains.     

Synthesis of some new five membered heterocycles,a facile synthesis of oxazolidinones

The synthesis and structural properties of two kinds of thiosemicarbazide derivatives ( 2a‐c and 3a‐c ) and one kind of semicarbazide derivatives ( 4a, 4b ) have been described. These compounds were synthesized by treating 2‐(4‐amino‐3‐alkyl‐5‐oxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐1‐yl)acetohydrazides ( 1a‐c ) with benzyl isothiocyanate, 3‐florophenyl isothiocyanate and benzylisocyanate, respectively. The synthesis of 4‐amino‐3‐alkyl‐1‐[(4‐alkyl‐5‐mercapto(or 5‐oxo)‐4H‐1,2,4‐triazol‐3‐yl)methyl]‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐ones ( 5a‐c, 6a‐c and 7 ) have been performed from the reaction with sodium hydroxide. On the other hand, the acidic treatment of compounds 2b, 3b and 4b has afforded 4‐amino‐3‐(4‐chlorobenzyl)‐1‐[(5‐alkylamino‐1,3,4‐thidazol(or 1,3,4‐oxazol)‐2‐yl)methyl]‐4,5‐dihydro‐1H‐1,2,4‐triazol‐5‐ones ( 8, 9 and 10 ). The condensation of thiosemi(or semi)carbazide derivatives ( 2a‐c, 3c and 4b ) with 4‐chlorophenacylbromide have resulted in the formation of 2‐[4‐amino‐3‐alkyl‐5‐oxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐1‐yl]‐N′‐(3,4‐dialkyl‐1,3‐thiazol(or oxazol)‐2(3H)‐yliden]acetohydrazides ( 11a‐c, 12, 13 ), while their condensation with chloroacetic acid has produced 2‐[4‐amino‐3‐alkyl‐5‐oxo‐4,5‐dihydro‐1H‐1,2,4‐triazol‐1‐yl]‐N′‐[3‐(3‐alkyl)]‐4‐oxo‐1,3‐thiazolidin(or oxazolidin)‐2‐yliden}acetohydrazides ( 14, 15 and 16 ). The spectral data and elemental analyses have support the proposed structures.     

Cyanoacetamide in heterocyclic chemistry: Synthesis,antitumor and antioxidant activities of some new benzothiophenes

Cyanoacylation of 2‐amino‐tetrahydrobenzothiophene‐3‐carboxylate ethyl ester with 3‐(3,5‐dimethyl‐1H‐pyrazol‐1‐yl)‐3‐oxopropanenitrile afforded cyanoacetamide 2 . The later was utilized as key intermediate for the synthesis of 3‐substituted 2‐iminocoumarins 3 , 4 , 5 , 6 and acrylamides 7a , b via Knoevenagel condensation with 2‐hydroxy‐1‐naphthaldehyde; 2‐hydroxybenzaldehyde; 1‐nitrosonaphthalen‐2‐ol; 7‐hydroxy‐5‐methoxy‐2‐methyl‐4‐oxo‐4H‐chromene‐6‐carbaldehyde; 4‐dimethylamino‐benzaldehyde; and 4‐piperidin‐1‐yl‐benzaldehyde in EtOH/piperidine. The derivatives 7a , b did not afford the pyrazoles 8a , b upon treating with phenyl hydrazine. Furthermore, coupling of 2 with 4‐amino‐1,5‐dimethyl‐2‐phenyl‐1H‐pyrazol‐3(2H)‐one and 4,6‐dimethyl‐1H‐pyrrolo[2,3‐b]pyridin‐3‐amine afforded the hydrazone derivatives 9 and 10 , respectively. The later derivative 10 was cyclized in acetic acid to afford the pyridopyrazolotriazine 11 . Finally, 2 was treated with dimethylformamide‐dimethylacetal (DMF‐DMA) to afford the dimethylaminoacrylamide 12 which underwent transamination with 4,6‐dimethyl‐1H‐pyrrolo[2,3‐b]pyridin‐3‐amine to afford the pyrazole 13 . Cyclization of compound 13 in acetic acid or pyridine was unsuccessful. The antitumor and antioxidant activities of the synthesized products were evaluated; several were found to exhibit promising antioxidant activities. J. Heterocyclic Chem., (2011).     

Functionalized 2‐Hydrazinobenzothiazole with Isatin and Some Carbohydrates under Conventional and Ultrasound Methods and Their Biological Activities

Several chemical reactions were carried out on 3‐(benzothiazol‐2‐yl‐hydrazono)‐1,3‐dihydro‐indol‐2‐one ( 2 ). 3‐(Benzothiazol‐2‐yl‐hydrazono)‐1‐alkyl‐1,3‐dihydro‐indol‐2‐one 3a , 3b , 3c have been achieved. Reaction of compound 2 with ethyl bromoacetate in the presence of K₂CO₃ resulted the uncyclized product 4 . Reaction of compound 2 with benzoyl chloride afforded dibenzoyl derivative 5 . Compound 2 was smoothly acetylated by acetic anhydride in pyridine to give diacetyl derivative 6b . Moreover, when compound 4 reacted with methyl hydrazine, it yielded dihydrazide derivative 7 , whereas the hydrazinolysis of this compound with hydrazine hydrate gave the monohydrazide derivative 8 . {N‐(Benzothiazol‐2‐yl‐N′‐(3‐oxo‐3,4‐dihydro‐2H‐1,2,4‐triaza‐fluoren‐9‐ylidene)hydrazino]‐acetic acid ethyl ester ( 9 ) was prepared by ring closure of compound 8 by the action of glacial acetic acid. In addition, the reaction of 2‐hydrazinobenzothiazole ( 1 ) with d ‐glucose and d ‐arabinose in the presence of acetic acid yielded the hydrazones 10a , 10b , respectively. Acetylation of compound 10b gave compound 11b . On the other hand, compound 13 was obtained by the reaction of compound 1 with gama‐d ‐galactolactone ( 12 ). Acetylation of compound 13 with acetic anhydride in pyridin gave the corresponding N¹‐acetyl‐N²‐(benzothiazolyl)‐2‐yl)‐2,3,4,5,6‐penta‐O‐acetyl‐d ‐galacto‐hydrazide ( 14 ). Better yields and shorter reaction times were achieved using ultrasound irradiation. The structural investigation of the new compounds is based on chemical and spectroscopic evidence. Some selected derivatives were studied for their antimicrobial and antiviral activities.     

N‐Azolylmethyl ketones as building blocks in heterocyclic synthesis: Synthesis of new polyfunctionally substituted azolylarylazophenols,azolylpyridones and azolylthiophenes

The title compounds 1a‐b and 2 reacted with 2‐arylhydrazonopropanals 3a‐c to yield polyfunctionally substituted azolylarylazophenols 5 and 8. The reaction of 1b and 2 with phenylisothiocyanate in the presence of α‐haloketones afforded the azolylthiophenes 12a,b and 13a,b. The reaction of 20 with α‐haloketone afforded 5‐benzotriazol‐1‐yl‐6‐methyl‐2‐(2‐oxopropylsulfanyl)nicotinonitrile 21 that was utilized as building blocks for the synthesis of condensed pyridines. Compound 21 was condensed with dimethylformamide dimethylacetal to yield thieno[2,3‐b]pyridin‐3‐yl‐N, N‐dimethylformamidine derivative 22. This was further cyclized with sodium hydride to 1H‐fhieno[2,3‐b; 4,5‐b']dipyridin‐4‐one derivative 23.     

2,6‐Bis(azaindole)pyridine: reactivity with iron(III) and copper(II) salts

1‐[6‐(1H‐Pyrrolo[2,3‐b]pyridin‐1‐yl)pyridin‐2‐yl]‐1H‐pyrrolo[2,3‐b]pyridin‐7‐ium tetrachloridoferrate(III), (C₁₉H₁₄N₅)[FeCl₄], (II), and [2,6‐bis(1H‐pyrrolo[2,3‐b]pyridin‐1‐yl‐κN⁷)pyridine‐κN]bis(nitrato‐κO)copper(II), [Cu(NO₃)₂(C₁₉H₁₃N₅)], (III), were prepared by self‐assembly from FeCl₃·6H₂O or Cu(NO₃)₂·3H₂O and 2,6‐bis(1H‐pyrrolo[2,3‐b]pyridin‐1‐yl)pyridine [commonly called 2,6‐bis(azaindole)pyridine, bap], C₁₉H₁₃N₅, (I). Compound (I) crystallizes with Z′ = 2 in the P space group, with both independent molecules adopting a trans–trans conformation. Compound (II) is a salt complex with weak C—H...Cl interactions giving rise to a zigzag network with π‐stacking down the a axis. Complex (III) lies across a twofold rotation axis in the C2/c space group. The Cu^II center in (III) has an N₃O₂ trigonal–bipyramidal environment. The nitrate ligand coordinates in a monodentate fashion, while the bap ligand adopts a twisted tridentate binding mode. C—H...O interactions give rise to a ribbon motif.     

18‐Crown‐6 Catalyzed Microwave‐mediated Synthesis of Symmetric Bis‐Heterocyclic Compounds under Solvent‐free Condition

An efficient, solvent‐free and 18‐crown‐6 catalyzed method for the synthesis of N‐alkyl‐4‐(4‐(5‐(2‐(alkyl‐amino)thiazol‐4‐yl)pyridin‐3‐yl)phenyl)thiazol‐2‐amine, N‐alkyl‐4‐(5‐(2‐alkyamino)thiazol‐4‐yl)pyridine‐3‐yl)thiazol‐2‐amine, and 4,4′‐bis‐{2‐[amino]‐4‐thiazolyl}biphenyl bis‐heterocyclic derivatives via microwave accelerated cyclization is presented.     

Two one‐dimensional coordination polymers generated from a new benzimidazole bridging ligand and CdX2 (X = Br and I)

The novel asymmetric bridging ligand 1‐[(pyridin‐3‐yl)methyl]‐2‐[4‐(pyridin‐3‐yl)phenyl]‐1H‐benzimidazole (L) has been used to construct the coordination polymers catena‐poly[[[dibromidocadmium(II)]‐μ₃‐1‐[(pyridin‐3‐yl)methyl]‐2‐[4‐(pyridin‐3‐yl)phenyl]‐1H‐benzimidazole] monohydrate], {[CdBr₂(C₂₄H₁₈N₄)]·H₂O}_n, (I), and catena‐poly[[diiodidocadmium(II)]‐μ₃‐1‐[(pyridin‐3‐yl)methyl]‐2‐[4‐(pyridin‐3‐yl)phenyl]‐1H‐benzimidazole], [CdI₂(C₂₄H₁₈N₄)]_n, (II). Compounds (I) and (II) are closely related one‐dimensional polymers based on 16‐ and 20‐membered macrocycles along the chains, but they are not isomorphous. The chains are crosslinked into a two‐dimensional network via hydrogen bonds and π–π interactions in (I), and into a three‐dimensional framework through π–π interactions in (II). One well‐ordered solvent water molecule per asymmetric unit is included in (I) and forms O...Br hydrogen bonds.     

Iron(III) Catecholates for Cellular Imaging and Photocytotoxicity in Red Light

Iron(III) complexes [Fe( L )( L′ )(NO₃)]—in which L is phenyl‐N,N‐bis[(pyridin‐2‐yl)methyl]methanamine ( 1 ), (anthracen‐9‐yl)‐N,N‐bis[(pyridin‐2‐yl)methyl]methanamine ( 2 ), (pyreny‐1‐yl)‐N,N‐bis[(pyridin‐2‐yl)methyl]methanamine ( 3 – 5 ), and L′ is catecholate ( 1 – 3 ), 4‐tert‐butyl catecholate ( 4 ), and 4‐(2‐aminoethyl)‐benzene‐1,2‐diolate ( 5 )—were synthesized and their photocytotoxic properties examined. The five electron‐paramagnetic complexes displayed a Fe^III/Fe^II redox couple near ?0.4 V versus a saturated calomel electrode (SCE) in DMF/0.1 m tetrabutylammonium perchlorate (TBAP). They showed unprecedented photocytotoxicity in red light (600–720 nm) to give IC₅₀≈15 μM in various cell lines by means of apoptosis to generate reactive oxygen species. They were ingested in the nucleus of HeLa and HaCaT cells in 4 h, thereby interacting favorably with calf thymus (ct)‐DNA and photocleaving pUC19 DNA in red light of 785 nm to form hydroxyl radicals.