Synthesis,properties, and catecholase-like activity of the [1,4-di(6′-methyl-2′-pyridyl)aminophthalazine]dimanganese(II) complex,Mn<Subscript>2</Subscript>(6′Me<Subscript>2</Subscript>PAP)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>

The preparation, spectroscopic properties, and catecholase-like activity of the dimanganese(II) complex [Mn₂(6′Me₂PAP)₂Cl₄] [6′Me₂PAP: 1,4-di(6′-methyl-2′-pyridyl)aminophthalazine] are reported. The title compound was suitable catalyst for the oxidation of 3,5-di-t-butylcatechol (3,5-DTBCH₂) to 3,5-di-t-butyl-1,2-benzoquinone (3,5-DTBQ) with dioxygen under ambient conditions in good yields. The catalytic oxidation was found to obey Michaelis–Menten type kinetics.     

Synthesis and catalase-like activity of dimanganese complexes with phthalazine-based ligands

Dimanganese complexes Mn₂ ^III(L¹)(OAc)₄ and Mn₂ ^III(L²)(OAc)₄ with the phthalazine-based ligands 1,4-di(2′-benzimidazolyl)aminophthalazine (H₂L¹) and 1,4-di(N-methyl-2′-benzimidazolyl)aminophthalazine (H₂L²) have been prepared and characterized. The complexes accelerate the disproportionation of H₂O₂ into water and dioxygen in buffered aqueous solutions in a near-neutral pH range thus can be regarded as catalase models. Results of kinetic measurements indicate a similar mechanism for the two catalysts, but formation of the proposed peroxo-adduct intermediate is less favored for Mn₂ ^III(L¹)(OAc)₄. It is presumed to be the reason for the lower rates for this catalyst even at higher pH.     

Unusual Hydrogen-bonding Networks Consisting of π-Extended 4,4′-Bipyridines and Chloranilic Acid

Hydrogen-bonding networks of π-extended 4,4′-bipyridines, 2,5-di(4-pyridyl)thiophene (1), 2,5-di(4-pyridyl)furan (2) and 1,4-di(4-pyridyl)benzene (3) with 2,5-dichloro-3,6-dihydroxy-1,4-benzoquinone (chloranilic acid, CA) have been investigated. The dipyridyl compounds afforded complexes 4 [(dication of 1)·(monoanion of CA)²], 5 [(dication of 2)·(dianion of CA)·(MeOH)] and 6 [(3)·(dication of 3)·(dianion of CA)·(H²O)⁶] with CA. X-ray structure analyses revealed the formation of unusual molecular tape and sheet structures involving N–H ?O, O–H ?O, C–H ?O and N–H ?N hydrogen bonds, where the aromatic spacer groups play an important role in constructing the unique crystal structures.     

A revised structure for plumbazeylanone

The structure of plumbazeylanone has been revised, by X-ray crystallography, to 1,2,3,4-tetrahydro-5-hydroxy-1,4-diketo-2-methyl-2,3-di(5′-hydroxy-2'-methyl-1,4-naphthoquinon-3′-yl)naphthalene.     

Catalytic oxidation of alcohols to carbonyl compounds with hydrogen peroxide using dinuclear iron complexes

Oxidation of primary and secondary alcohols has been studied in the presence of [Fe(ind)Cl]₂O (1) and [Fe₂(OMe)₂(PAP)Cl₄] (2) (indH = 1,3-bis(2′-pyridylimino)isoindoline; PAP = 1,4-di(2′-pyridyl)aminophthalazine) as catalysts using hydrogen peroxide as primary oxidant. The complexes were found to be suitable catalysts for the oxidation of alcohols to the corresponding carbonyl compounds in acetone as solvent. The reactivity of the alcohols is in the order primary < secondary < cyclic secondary < aromatic. The reaction mechanism in the case of 1 probable involves an iron-based oxidant, while in the case of 2 a free-radical mechanism is suggested.     

Synthesis of conjugated (1E,3E)- and (1Z,3Z)-1,4-di(n-pyridyl) (or n-quinolyl)-1,3-butadienes from n-(2′-chloroethenyl)pyridine (or quinoline)

The homocoupling reaction between the conjugated n-(2-chloroethenyl)pyridine; n, 2-, 3- and 4- (or quinoline; n, 2- and 4-) mediated by zero-valent nickel complexes at room temperature affords to the corresponding 1,4-diaryl-1,3-butadiene, always as the 1E,3E stereoisomer. The yield in 1,4-diaryl-1,3-butadiene increases with the nickel catalyst and hence, the active zero-valent nickel catalyst is not regenerated during the homocoupling reaction.The stereospecific synthesis of (1Z,3Z)-1,4-di(4′-pyridyl)-1,3-butadiene stereoisomer was efficiently carried out by partial hydrogenation of the appropriate 1,4-di(4′-pyridyl)-1,3-butadiyne.     

Syntheses Based on 4-Chloro-1-[3,5-di(trifluoromethyl)phenyl]-, 4-Chloro-1-(2,4-difluorophenyl)-5-formyl-3-methyl-6,7-dihydroindazoles,and 4-Chloro-5-formyl-3-methyl-1-(2-pyridyl)-6,7-dihydroindazoles

Vilsmeier formylation of 1-[3,5-di(trifluoromethyl)phenyl]- and 1-(2,4-difluorophenyl)-3-methyl-4-oxo-4,5,6,7-tetrahydroindazoles gave the corresponding 1-aryl-4-chloro-5-formyl-3-methyl-6,7-dihydroindazoles. Reaction of the latter with amidines, o-phenylenediamine, hydrazine, or hydroxylamine gave a series of 1-aryl-3-methyl-6,6-dihydroindazoles annelated at positions 4 and 5. The reaction of 4-chloro-5-formyl-3-methyl-1-(2-pyridyl)-6,7-dihydroindazole with substituted anilines gave 5-arylaminomethylene-4-oxo- or 5-arylaminomethylene-4-arylimino-3-methyl-1-(2-pyridyl)-4,5,6,7-tetrahydroindazoles depending on the molar ratio of reagents and the nucleophilicity of the amines.__________Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 740–750, May, 2005.     

Determination of technetium based on quenching of the fluorescence of some organic compounds,with application to vegetation

Technetium is an effective quencher of the fluorescence produced by 2,5-diphenyloxazole (PPO), 1,4-bis(4-methyl-5-phenyl-2-oxazolyl)benzene (POPOP) and 2,2′-pyridil [1,2-dioxo-1,2-bis(2-pyridyl)ethane]. Spectrofluorimetric procedures for 0.01–12 μg Tc ml^?1 with PPO and 0.1–12 μg ml^?1 with 2,2′-pyridil, and a spectrophotometric method for 1–15 μg ml^?1 are described. The distribution of technetium in vegetation is measured by applying the PPO method.     

Synthesis and properties of N-methylmorpholinium 6-methyl-4-(4-pyridyl)-5-phenylcarbamoyl-3-cyano-1,4-dihydropyridine-2-thiolate

Condensation of acetoacetic acid anilide, 4-pyridyl aldehyde, cyanothioacetamide and N-methylmorpholine gave N-methylmorpholinium 6-methyl-4-(4-pyridyl)-5-phenylcarbamoyl-3-cyano-1,4-dihydropyridine-2-thiolate from which were obtained the corresponding substituted pyridinethiones, 2-alkylthio-1,4-dihydropyridines and 3-amino-2-benzoyl-6-methyl-4-(4-pyridyl)-5-phenylcarbamoylthieno[2,3-b]pyridine.T. G. Shevchenko Lugansk Pedagogical Institute, Lugansk 348011. N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, Moscow 117913. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 672–675, May, 1997.     

Activating Chalcogen Bonding (ChB) in Alkylseleno/Alkyltelluroacetylenes toward Chalcogen Bonding Directionality Control

Activation of a deep electron-deficient area on chalcogen atoms (Ch=Se, Te) is demonstrated in alkynyl chalcogen derivatives, in the prolongation of the (C≡)C−Ch bond. The solid-state structures of 1,4-bis(methylselenoethynyl)perfluorobenzene ( 1Se ) show the formation of recurrent chalcogen-bonded (ChB) motifs. Association of 1Se and the tellurium analogue 1Te with 4,4′-bipyridine and with the stronger Lewis base 1,4-di(4-pyridyl)piperazine gives 1:1 co-crystals with 1D extended structures linked by short and directional ChB interactions, comparable to those observed with the corresponding halogen bond (XB) donor, 1,4-bis(iodoethynyl)-perfluorobenzene. This “alkynyl” approach for chalcogen activation provides the crystal-engineering community with efficient, and neutral ChB donors for the elaboration of supramolecular 1D (and potentially 2D or 3D) architectures, with a degree of strength and predictability comparable to that of halogen bonding in iodoacetylene derivatives.     

Cycloaddition von N-Phenylmaleinimid an (1,2,3,6-Tetrahydropyridyl)-indole

1-Methyl-2-and 1-methyl-3-(1-methyl-1,2,3,6-tetrahydro-4-pyridyl)-indole undergo 1,4-cycloaddition (formally of the DIELS -ALDER -type) with N-phenyl-maleimide, leading to the pentacyclic compounds III and IV.     

Synthesis and Properties of New Laser Dyes Containing 4-(2-Thienyl)Pyridine Skeleton

Abstract

Three 4-(oligothienyl)pyridines and four α,ω-di(4-pyridyl)oligo-thiophenes were prepared and the effect of conjugated thiophene rings on their fluorescence properties were examined. 4-(2,2′-Bithienyl-5-yl)pyridine and 2,5-di(4-pyridyl)thiophene exhibited laser dye emission upon pumping with a nitrogen laser and the conversion efficiency of the latter was 1.5 times as great as that of a commercial laser dye PBBO at 400 nm.     

Peculiarities of the behavior of succinyl dichloride in Friedel-Crafts reaction with thiophenes*

The reactions of thiophene, 2-methyl-, and 2-bromothiophene with succinyl dichloride in the presence of AlCl₃, TiCl₄, and SnCl₄ have been studied. The effect of the acylation conditions, the relative amounts and nature of the Lewis acid on the ratio and yields of the 1,4-di(2-thienyl)-1,4-diones and 4-oxo-4-(2-thienyl)butyric acids formed have been demonstrated. Under the reaction conditions, the formation of 4,4-di(2-thienyl)but-3-enoic acids (the main products in many cases) and also 4,4-di(2-thienyl)-butyrolactones was demonstrated.     

Reductive cleavage of dichalcogenide bonds

Electrochemical reduction of 1,2-di(2,4,6-triphenylpyridinium-l)ethane, 1,4-di(2,4,6-triphenylpyridinium-1)butane, 1,6-di(2,4,6-triphenylpyridinium-l)hexane, 1,4-di(N-methyl-4,6-diphenylpyridinium-2)benzene, and 2,7-di(N-methyl-4,6-diphenylpyridinium-2)fluorene in solutions of DMF and MeCN in the potential range from−0.8 to −1.7 V (SCE) was studied by CV. The successive formation of stable radical cations, biradicals, and dianions was investigated by semiempirical MO calculations at the PM3 level.     

A green approach for the electroorganic synthesis of 2-[(4-methyl-2-pyridyl)amino]-1,4-benzenediol derivatives in aqueous solution

The electrochemical synthesis of some new 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives was performed via the electrochemical oxidation of hydroquinones in the presence of 2-amino-4-methylpyridine in an aqueous solution. The results demonstrate that electrogenerated p-benzoquinone participated in the Michael-type addition reaction via an electrochemical–chemical (EC) reaction mechanism pathway and converted to the corresponding 2-[(4-methyl-2-pyridyl)amino)-1,4-benzenediol derivatives. These new compounds have been synthesized in high yields and purity without using any toxic reagents or catalyst at the surface of carbon electrode.     

Conformations,vibrational spectra and force field of 1-methyl-2-(2′-pyridyl)benzimidazole: experimental data and density functional theory investigation in comparison with 2-(2′-pyridyl)benzimidazole

The molecular structure, conformational equilibria, vibrational spectra and molecular force field of 1-methyl-2-(2′-pyridyl)benzimidazole have been determined at the HF, MP2 and DFT/(B3LYP, BVP86) levels with 6-31+G(d,p) and TZVP basis sets. The torsional potentials for the rotation around the C1–C2 pivotal bond have been calculated at the B3LYP/6-31+G(d,p) and BVP86/TZVP levels of theory for gaseous and aqueous 1-methyl-2-(2′-pyridyl)benzimidazole. FT-Raman (3500–10 cm^?1) and FT-IR (3900–400 cm^?1) spectra of solid 1-methyl-2-(2′-pyridyl)benzimidazole have been recorded and interpreted on a base of calculated potential energy distribution. The results of the experimental and theoretical study of vibrational spectra and molecular structure of 1-methyl 2-(2′-pyridyl)benzimidazole are considered in comparison with similar data for 2-(2′-pyridyl)benzimidazole.

     

The reaction of β-lactam carbenes with 3,6-dipyridyltetrazines: switch of reaction pathways by 2-pyridyl and 4-pyridyl substituents of tetrazines

The reactions of β-lactam carbenes with both 3,6-di(2-pyridyl)tetrazine and 3,6-di(4-pyridyl)tetrazine were studied. It was found that β-lactam carbenes reacted with 3,6-di(2-pyridyl)tetrazine to produce 5-triazolo[1,5-a]pyridylpyrrol-2-ones in good yields, while with 3,6-di(4-pyridyl)tetrazine, they afforded pyrido[c]cyclopenta[b]pyrrol-2-ones in moderate yields. Both reactions were proposed to follow cascade mechanisms containing a 3,6a-dipyridylpyrrolo[3,2-c]pyrazol-5-one intermediate. The different pathways of the transformation of pyrrolo[3,2-c]pyrazol-5-ones were switched by the 2- and 4-pyridyl substituents. This work not only provided a simple and efficient strategy for the construction of novel triazolo[1,5-a]pyridine and pyrido[c]cyclopenta[b]pyrrole derivatives, respectively, but also revealed two different thermal transformation patterns of 3H-pyrazole compounds.     

Reactivities of dianions of pyridyl phenyl ketones

Substituted pyridylphenylcarbinols are formed in the reaction of the dianions of isomeric pyridyl phenyl ketones with alkyl halides, aldehydes, and benzonitrile. The reaction of the dianion of 3-pyridyl phenyl ketone with benzophenone, in contrast to the analogous reaction of the dianion of 2-pyridyl phenyl ketone, gives 5-benzoyl-2-diphenylhydroxymethyl-1,2-dihydropyridine. It is assumed that the observed reaction includes one-electron transfer and the formation of two anion radicals. Recombination of the anion radical of 3-pyridyl phenyl ketone leads to 5,5′-dibenzoyl-2,2′-di(1,2-dihydropyridyl).     

Oligomerization of vinyl monomers. XXI. Characterization of model carbanions of living poly(2-vinylpyridine) in THF by 7Li-NMR and conductance: Evidence for the occurrence and nature of triple ion formation

The formation of triple anions is demonstrated by ⁷Li-NMR in THF solutions of 1-lithio-1-(2-pyridyl)ethane, 1-lithio-1(3-methyl-2-pyridyl)ethane, and 1-lithio-1,3-di(2-pyridyl) butane. Good agreement with conductance data was demonstrated in the case of 1 . Triple anion formation in the case of 2 was found to be about twice as high as in 1 possibly as a result of the greater charge density on the carbanion in the case of 2 .