Mechanism of the condensation reaction between 1-aryl- and heteroaryl-1,4-dihydro-3(2H)-isoquinolinones and aldehydes

4-Benzylidene-1-phenyl-1,4-dihydro-3(2H)-isoquinolinone, the intermediary product of the carbonyl condensation reaction between 1-phenyl-1,4-dihydro-3(2H)-isoquinolinone and benzaldehyde, rearranges in the presence of an equivalent quantity of sodium hydride into 4-benzyl-1-phenyl-3(2H)-isoquinolinone. As the possibility of the migration of the hydrogen at C-1 in the form of a proton or a hydrogen atom (radical reaction) was excluded, the mechanism of the rearrangement could be depicted as an intermolecular hydride anion migration. In case of the 1-(4-pyridyl)- and 1-(3-pyridyl)-1,4-dihydro-3(2H)-isoquinolinones, however, the rearrangement can be carried out also in polyphosphoric acid and in this case a proton loss-proton gain mechanism was proved.     

Novel 1,4-dihydropyridine calcium antagonists. I. Synthesis and hypotensive activity of 4-(substituted pyridyl)-1,4-dihydropyridine derivatives

A series of 4-(substituted pyridyl)-1,4-dihydropyridine derivatives were synthesized and their hypotensive effects examined. Several compounds, 2-(N-benzyl-N-methylamino)ethyl methyl 1,4-dihydro-2,6-dimethyl-4-(3-nitro-2-pyridyl)-3,5-pyridinedicarboxylate (2b), its 4-(4-nitro-2-pyridyl) analogue (2g), 4-(3-trifluoromethyl-2-pyridyl) analogue (2c), 4-(2-trifluoromethyl-3-pyridyl) analogue (3e), 4-(4-cyano-2-pyridyl) analogue (2e), 4-(2-cyano-3-pyridyl) analogue (3d), and 4-(6-bromo-2-pyridyl) analogue (2i), were found to have a hypotensive activity parallel to that of nicardipine; 2c and 3e, in particular, had approximately twice the duration of nicardipine, and 2e had the most potent hypotensive activity of all the derivatives synthesized.     

A one-flask synthesis and characterization of novel symmetrical pyridyl monoselenides and X-ray crystal structure of bis(5-bromo-2-pyridyl) selenide and bis(2-bromo-5-pyridyl) selenide

The present work reports an efficient one-pot synthesis of symmetrical pyridyl monoselenides by the reaction of bromo-/iodopyridines with the isopropylmagnesium chloride, ⁱPrMgCl followed by quenching with selenyl chloride, SeCl₂. The current methodology constitutes a convenient synthesis of bis(5-bromo-2-pyridyl) selenide (I), bis(2-bromo-5-pyridyl) selenide (II) and bis(2,5-dibromo-3-pyridyl) selenide (III) under cryogenic conditions requiring shorter time duration to give satisfactory yields. The hitherto unknown compounds have been characterized by elemental analysis and various spectroscopic techniques i.e., ¹H NMR, ¹³C NMR, FT-IR, mass spectrometry and X-ray crystallography.     

Synthesis of 1,4-bis(4-pyridyl)butadiyne

2-Methyl-4-(4-pyridyl)-3-butyn-2-ol ( 2 ) was prepared in 70% yield by the reaction of 4-bromopyridine with 2-methyl-3-butyn-2-ol in diethylamine in the presence of bis(triphenylphosphine)palladium(II) chloride and copper(I) iodide. Removal of the protective group in 2 by refluxing with sodium hydroxide in toluene yields (90%) 4-ethynylpyridine ( 3 ). Oxidative coupling of 3 in pyridine by dioxygen in the presence of copper(I) chloride produces a 92% yield of 1,4-bis(4-pyridyl)butadiyne.     

Polarographic study of bis(2-pyridyl)disulphide di-N-oxide and bis(2-quinolyl)disulphide di-N-oxide in aqueous ethanol

The polarographic reduction of bis(2-pyridyl)- and of bis(2-quinolyl)disulphide di-N-oxide in aqueous alcohol yields aryl mercaptans. The electrode reaction is kinetically controlled by an initial one-electron transfer step, and values for the transfer coefficients and the specific heterogeneous rate constants for the forward reactions are presented. The polar N-oxide function in the alpha-position withdraws electrons from the disulphide bond, making the half-wave potential less negative than that of the diphenyl disulphide. The pk(a) values of the mercapto compounds formed have been evaluated and the low values obtained for the heterocyclic N-oxides are further evidence for tautomerism in these compounds.     

1-环丙基-6-氟-7-(4-酰基-1-哌嗪基)-1,4-二氢-4-氧代喹啉-3-羧酸的合成及其抗菌活性研究

以1-环丙基-6-氟-7-氯-1, 4-二氢-4-氧代喹啉-3-羧酸为原料经过两步反应合成出了16个新的1-环丙基-6-氟-7-(4-酰基-1-哌嗪基)-1, 4-二氢-4-氧代喹啉-3-羧酸, 并利用IR, ¹H NMR, ¹³C NMR, MS谱及元素分析对其结构进行了表征. 初步体外抗菌活性研究表明, 大部分目标化合物对大肠杆菌有一定的抑菌活性, MIC值在0.312～20 g/mL之间, 但活性低于对照物环丙沙星和氧氟沙星; 目标化合物对绿脓杆菌无抑菌活性, 最低抑菌浓度(MIC)均大于20 g/mL.     

Synthesis and spectroelectrochemical studies of mixed heteroleptic chelate complexes of ruthenium(II) with 1,8-bis(2-pyridyl)-3,6-dithiaoctane (pdto) and substituted 1,10-phenanthrolines

Reaction of dichlorotris(triphenylphosphine) ruthenium(II) [RuCl(2)(PPh(3))(3)] with 1,8-bis(2-pyridyl)-3,6-dithiaoctane (pdto), a (N(2)S(2)) tetradentate donor, yields a new compound [Ru(pdto)(PPh(3))Cl]Cl (1), which has been fully characterized. (1)H and (31)P NMR studies of 1 in acetonitrile at several temperatures show the substitution of both coordinated chloride and triphenylphosphine with two molecules of acetonitrile, as confirmed by the isolation of the complex [Ru(pdto)(CH(3)CN)(2)]Cl(2) (2). Cyclic voltammetric and spectroelectrochemical techniques allowed us to determine the electrochemical behavior of compound 1. The substitution of the chloride and triphenylphosphine by acetonitrile molecules in the Ru(II) coordination sphere of compound 1 was also established by electrochemical studies. The easy substitution of this complex led us to use it as starting material to synthesize the substituted phenanthroline coordination compounds with (pdto) and ruthenium(II), [Ru(pdto)(4,7-diphenyl-1,10-phenanthroline)]Cl(2).4H(2)O (3), [Ru(pdto)(1,10-phenanthroline)]Cl(2).5H(2)O (4), [Ru(pdto)(5,6-dimethyl-1,10-phenanthroline)]Cl(2).5H(2)O (5), [Ru(pdto)(4,7-dimethyl-1,10-phenanthroline)]Cl(2).3H(2)O (6), and [Ru(pdto)(3,4,7,8-tetramethyl-1,10-phenanthroline)]Cl(2).4H(2)O (7). These compounds were fully characterized, and the crystal structure of 4 was obtained. Cyclic voltammetric and spectroelectrochemical techniques allowed us to determine their electrochemical behavior. The electrochemical oxidation processes in these compounds are related to the oxidation of ionic chlorides, and to the reversible transformation from Ru(II) to Ru(III). On the other hand, a single reduction process is associated to the reduction of the substituted phenanthroline in the coordination compound. The E(1/2) (phen/phen(-)) and E(1/2) (Ru(II)/Ru(III)) for the compounds (3-7) were evaluated, and, as expected, the modification of the substituted 1,10-phenanthrolines in the complexes also modifies the redox potentials. Correlations of both electrochemical potentials with pK(a) of the free 1,10-phenathrolines, lambda(max) MLCT transition band, and chemical shifts of phenanthrolines in these complexes were found, possibly as a consequence of the change in the electron density of the Ru(II) and the coordinated phenanthroline.     

Electrocatalytic properties of guanine, adenine, guanosine-5'-monophosphate, and ssDNA by Fe(II) bis(2,2':6',2'-terpyridine), Fe(II) tris(1,10-phenanthroline), and poly-Fe(II) tris(5-amino-1,10-phenanthroline)

The electrocatalytic oxidations of guanine, adenine, guanosine-5'-monophosphate(GMP) and ssDNA were performed in the presence of Fe(II) bis(2,2':6',2'-terpyridine) and Fe(II) tris(1,10-phenanthroline) complexes as homogeneous catalysts by cyclic voltammetric methods. The Fe(II/III) redox couple of these compounds is responsible for their catalytic properties. The electrocatalytic oxidation current of above substrates were developed from the anodic peak currents of Fe(II) bis(2,2':6',2'-terpyridine) and Fe(II) tris(1,10-phenanthroline) complexes at about +0.93 V and 0.97 V, respectively. The electrocatalytic oxidative properties of guanine by Fe(II) bis(2,2':6',2'-terpyridine) complex was measured by amperometry method using the rotating disk electrodes. Electropolymerization of Fe(II) tris(5-amino-1,10-phenanthroline) complex produced thin polymer films on gold and glassy carbon electrodes. The electrochemical quartz crystal microbalance (EQCM) and cyclic voltammetry were used to study the in situ growth of the polymer. The poly(FeII(5-NH(2)-1,10-phen)(3)) exhibited a good electrocatalytic oxidation towards guanine and also for the mixture of guanine and adenine too.     

Synthesis of heteroleptic bis(diimine)carbonylchlororuthenium(II) complexes from photodecarbonylated precursors

The reactions of bidentate diimine ligands (L2) with binuclear [Ru(L1)(CO)Cl2]2 complexes [L1 not equal to L2 = 2,2'-bipyridine (bpy), 4,4'-dimethyl-2,2'-bipyridine (4,4'-Me2bpy), 5,5'-dimethyl-2,2'-bipyridine (5,5'-Me2bpy), 1,10-phenanthroline (phen), 4,7-dimethyl-1,10-phenanthroline (4,7-Me2phen), 5,6-dimethyl-1,10-phenanthroline (5,6-Me2phen), di(2-pyridyl)ketone (dpk), di(2-pyridyl)amine (dpa)] result in cleavage of the dichloride bridge and the formation of cationic [Ru(L1)(L2)(CO)Cl]+ complexes. In addition to spectroscopic characterization, the structures of the [Ru(bpy)(phen)(CO)Cl]+, [Ru(4,4'-Me2bpy)(5,6-Me2phen)(CO)Cl]+ (as two polymorphs), [Ru(4,4'-Me2bpy)(4,7-Me2phen)(CO)Cl]+, [Ru(bpy)(dpa)(CO)Cl]+, [Ru(5,5'-Me2bpy)(dpa)(CO)Cl]+, [Ru(bpy)(dpk)(CO)Cl]+, and [Ru(4,4'-Me2bpy)(dpk)(CO)Cl]+ cations were confirmed by single crystal X-ray diffraction studies. In each case, the structurally characterized complex had the carbonyl ligand trans to a nitrogen from the incoming diimine ligand, these complexes corresponding to the main isomers isolated from the reaction mixtures. The synthesis of [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)(NO3)]+ from [Ru(4,4'-Me2bpy)(5,6-Me2bpy)(CO)Cl]+ and AgNO3 demonstrates that exchange of the chloro ligand can be achieved.     

Spectral and electrochemical studies of bis(diimine)copper(II) complexes in anionic, cationic and nonionic micelles

The spectral and redox behavior of bis(diimine)copper(II) complexes, where diimine is bipyridine, 1,10-phenanthroline, 4-methyl-1,10-phenanthroline, 5-methyl-1,10-phenanthroline, 5-nitro-1,10-phenanthroline, 4,7-dimethyl-1,10-phenanthroline, 5,6-dimethyl-1,10-phenanthroline, 2,9-dimethyl-1,10-phenanthroline, 3,4,7,8-tetramethyl-1,10-phenanthroline and dipyrido-[3,2-d:2',3'-f]-quinoxaline, are significantly different in aqueous and in aqueous SDS, CTAB and Triton X-100 micellar solutions. The (1)H NMR spectral study in aqueous (D(2)O) and aqueous micelles reveals that the Cu(II) complexes interact more strongly with SDS than with CTAB and Triton X-100 micelles and at sites on SDS micelles different from those on the latter. Ligand Field spectral studies reveal that the complexes exist as the dicationic aquated species [Cu(diimine)(2)(H(2)O)(2)](2+), which interacts strongly with the anionic SDS micelles through columbic forces. However, they exist as [Cu(diimine)(2)(H(2)O)Cl](+) and/or [Cu(diimine)(2)H(2)] located in the hydrophobic microenvironments in Triton X-100 and CTAB micelles. The attainment of reversibility of the redox systems in the micellar microenvironments is remarkable and this illustrates that the Cu(II) and Cu(I) species undergo stereochemical changes suitable for reversible electron-transfer. The remarkable differences in spectral and electrochemical properties of Cu(II) complexes in aqueous and aqueous micellar solutions illustrate that the complexes are nestled largely within the micellar environments and imply that the accessibilities of the complexes to electron-transfer are different and are dependent on the nature of micelles as well as the nature and hydrophobicity of the diimine ligands.     

Extraction-spectrophotometric determination of sulphide and sulphite in waters based on formation of the bis(2,9-dimethyl-1,10-phenanthroline) copper(I) ion

A spectrophotometric method is described for the determination of sulphide or sulphite. The bis(2,9-dimethyl-1,10-phenanthroline)copper(II) ion is reduced at pH 10 by sulphide in the presence of formaldehyde and by sulphide and sulphite in its absence. The resulting copper(I) complex is extracted into chloroform and measured. With any convenient sample volume between 1 and 100 ml, the limits of detection are 0.1 mg for sulphide and 0.25 μg for sulphite. The method is unaffected by iron(II) and nitrite, in concentrations of 100 and 1000 mg l^-1, respectively.     

Reaction of 5,5'-(1,4-Phenylene)bis(3-aryl-2-oxaspiro[5.5]undec-3-en-1-ones) with Methyl 1-Bromocyclohexanecarboxylate and Zinc

Russian Journal of Organic Chemistry - The reaction of 3,3'-(1,4-phenylene)bis(1-phenylprop-2-en-1-ones) with the Reformatsky reagent obtained from methyl 1-bromocyclohexanecarboxylate and zinc...     

Copper(I)-2-(2′-pyridyl)benzimidazole catalyzed N-arylation of indoles

CuI-2-(2′-pyridyl)benzimidazole catalyst system can serve efficiently to promote N-arylation of various indoles to afford the N-arylated indoles. The bidentate ligand, 2-(2′-pyridyl)benzimidazole was proved superior to monodentate nitrogen-based ligands and well-known bidentate ligands such as 2,2′-bipyridyl and 1,10-phenanthroline.     

Synthesis of New Substituted 2,3-Dihydro-1,4-dioxin-2-ones and 1,4-Dioxan-2-ones

3-Alkyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones reacted with acetyl chloride in the presence of zinc(II) chloride to give the corresponding 3-alkyl-5-acetyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones. Oxidation of the latter with hydrogen peroxide in formic acid, followed by treatment with magnesium bromide, afforded 3-alkyl-6-methyl-1,4-dioxane-2,5-diones. Successive chlorination and dechlorination of 6-hydroxymethyl-1,4-dioxan-2-ones yielded 6-methylene-1,4-dioxan-2-ones.     

Reaction of 2-bromomethyl-1,3-thiaselenole with thiourea: en route to the first representatives of 2-(organylsulfanyl)-2,3-dihydro-1,4-thiaselenines

The regioselective reaction of 2-bromomethyl-1,3-thiaselenole 1 with thiourea is accompanied by rearrangement, expanding the ring to afford the corresponding six-membered isothiuronium salt, 2-[amino(imino)methyl]sulfanyl-2,3-dihydro-1,4-thiaselenine hydrobromide 2, a synthon of the 2,3-dihydro-1,4-thiaselenin-2-ylthiolate anion. The latter was used for the synthesis of the first representatives of 2-(organylsulfanyl)-2,3-dihydro-1,4-thiaselenines 3a–g, bis(2,3-dihydro-1,4-thiaselenin-2-yl) disulfide 5 and 1,6-bis(2,3-dihydro-1,4-thiaselenin-2-ylsulfanyl)hexane 6.     

Synthesis of New Substituted 2,3-Dihydro-1,4-dioxin-2-ones and 1,4-Dioxan-2-ones

3-Alkyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones reacted with acetyl chloride in the presence of zinc(II) chloride to give 5-acetyl-3-alkyl-6-methyl-2,3-dihydro-1,4-dioxin-2-ones. Oxidation of the latter with hydrogen peroxide in formic acid, followed by treatment with magnesium bromide, afforded 3-alkyl-6-methyl-1,4-dioxane-2,5-diones. Chlorination of 6-hydroxymethyl-1,4-dioxan-2-ones with thionyl chloride and subsequent dehydrochlorination led to formation of 6-methylene-1,4-dioxan-2-ones.     

Bimetallic bis(diphenylphosphino)acetylene bridged copper(I) complexes with 1,10-phenanthroline derivatives: synthesis,crystal structure,and spectroscopic characterization

A new series of bimetallic bis(diphenylphosphino)acetylene-bridged copper(I) 1,10-phenanthroline complexes, [Cu₂(dppa)₂(L)₂](BF₄)₂; L?=?1,10-phenanthroline (1); 4-methyl-1,10-phenanthroline (2); 4,7-dimethyl-1,10-phenanthroline (3); and 2,9-dimethyl-1,10-phenanthroline (4), have been prepared and characterized by spectroscopic methods. The X-ray structures of 1 and 4 were determined. The structures consist of centrosymmetric bimetallic 10-membered chair-like dimetallacycles. In 1, intermolecular C–H?π interactions result in bending of the phenanthroline ligand and sterically induced lengthening of one Cu–P bond. In 1–4, the ³¹P NMR downfield coordination shift, relative to the free ligand, correlates with the basic strength of the 1,10-phenanthroline ligands.     

Synthesis of 5-amino-2,3-dihydro-1H-1,4-benzodiazepines

A number of 5-amino-2,3-dihydro-lH-1,4-benzodiazepines (II) have been prepared from the reaction of 5-methylmercapto-2,3-dihydro-1H-1,4-benzodiazepine (I) with amines. Another alternate approach based on the cyclodehydration of the ureic compounds (IV) was unsuccessful. The synthesis of I was accomplished by methylation of the 1,2,3,4-tetrahydro-5H-5-thioxo-1,4-benzodiazepine (VI) with dimethyl sulfate in methanol-dioxane. Another attempted method for the synthesis of I is also presented. J. Heterocyclic Chem., 14, 985 (1977)     

Reinterpretation of long-range 1H-19F spin—spin coupling in 1,4-dihydro-1,4-epoxynaphthalenes and related systems

The long-range ¹H-¹⁹F coupling reported earlier for the bridgehead proton(s) in 1,4-dihydro-1,4-epoxynaphthalenes (e.g., $\text{1}$) is shown unequivocally to involve the distal fluorine by a five-bond zig-zag coupling pathway.     

Synthesis of substituted bis(3,3-dialkyl-3,4-dihydro-1-isoquinolyl)methanes

Symmetrical and non-symmetrical substituted bis(3,4-dihydro-1-isoquinolyl)methanes were synthesized by fusion of substituted 1-methylthio-3,4-dihydroisoquinolines with 1-methyl-3,4-dihydroisoquinolines and by the Ritter reaction of 1,1-dialkyl-2-arylethanols with 1-cyanomethylidene-1,2,3,4-tetrahydroisoquinoline or malononitrile.