New syntheses of N,N′-diaryl-substituted quinone diimines: I. Synthesis of N,N′-bis(4-aminophenyl)-1,4-benzoquinone diimine

Russian Journal of Organic Chemistry - Oxidative condensation of p-phenylenediamine by the action of K2S2O8 in acetic acid afforded N,N′-bis(4-aminophenyl)-1,4-benzoquinone diimine which...     

Anti-β-amyloid aggregation activity of enantiomeric furolactone-type lignans from Archidendron clypearia (Jack) I.C.N.

Abstract

The phytochemical investigation on the twigs and leaves of Archidendron clypearia (Jack) I.C.N. led to the isolation of three pairs of furolactone-type lignans enantiomers, including a pair of new compounds (1R,5S,6S)-Kachiranol (1a) and (1S,5R,6R)-Kachiranol (1b) and four known compounds (2a/2b and 3a/3b). Separation of the furolactone-type lignans enantiomeric mixtures was achieved using chiral HPLC for the first time. Their structures were determined by spectroscopic analysis and comparison between the experimental and calculated electronic circular dichroism (ECD) spectra. All optical pure compounds were evaluated for their inhibitory effects on β-amyloid aggregation by ThT assay. Among them, the inhibitory activity of the compound 1b (71.1%) was higher than the positive control (61.0%) and other compounds. In addition, molecular dynamics and molecular docking were employed to explore the binding relationship between the ligand and the receptor.     

Aminoamidines. 5. Synthesis and acetylation of N,N1,N2-triaryl-substituted β-aminoamidines

Triaryl-substituted -aminoamidines were obtained by the reaction of ,-unsaturated N-arylimidoyl chlorides with arylamines. Acylation of the products gave the products from monosubstitution at the -amino group. Triaryl-substituted -aminoamidines react with phosgene and with oxalyl chloride to form 4-aryliminoperhydropyrimidin-2-ones and 5-aryliminoperhydro-1,4-diazepine-2,3-diones, respectively.For previous communication, see [1].A. E. Arbuzov Institute of Organic and Physical Chemistry, Kazan' Scientific Center, Russian Academy of Sciences, 420083 Kazan'. Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp. 2633–2642, November, 1992.     

Synthesis of guanidines via the I2 mediated desulfurization of N,N′-di-Boc-thiourea

The I₂ mediated desulfurization of N,N′-di-Boc-thiourea was developed. Various primary amines, including sterically and electronically deactivated primary amines, were transformed into the corresponding bis-Boc protected guanidines under mild conditions.     

Study of N,N′-dihydroxyethyldithiooxamide by X-ray diffraction,u.v.-vis,NMR, Raman and i.r. spectroscopy

The vibrational, NMR and electronic spectra of HO(CH₂)_xNHCSCSNH(CH₂)_xOH (x = 2,3,5,6) are discussed. A vibrational analysis has been proposed for the N,N′-dihydroxyethyldithiooxamide (x = 2) and its deuterated (NH/ND, OH/OD) analogue. The structure of N,N′-DHEDTO was solved by X-ray analysis. M_r = 208, monoclinic, space group P2₁/n, a = 9.8800(5) Å, b = 11.3260(7) Å, c = 9.7806(8) Å, β = 119.366(5)°, V = 953.8 ų, Z = 4, Dc = 1.365 Mgm⁻¹,μ(CuKα) = 0.47 mm⁻¹, F(000) = 440.00, T = 300 K. Final conventional R-factor = 0.036, R_w = 0.037, for 1608 unique reflections with I > 3.σ(I) out of 1800 measurements. The structure was solved using the automatic programs PATSYS and DIRDIF. The two νOH bands in the i.r. spectrum are in agreement with the crystallographic structure, which proposes that the unit cell of the compound consists of two independent molecules.     

Cyclopalladation of N,N,N′,N′-tetramethylisophthalthioamide

Summary N,N,N,N-Tetramethylisophthalthioamide (Hmpt) was cyclopalladated with PdCl₂ in hot dimethylsulphoxide to give [PdCl(mpt)]. The structure was determined by X-ray analysis. The thioamide is metallated at C(2) to act as an S528-01C528-02S tridentate anionic ligand. There is appreciable steric repulsion between the benzene ring H(4, 6) and the dimethylamino groups. The hydrogens and the methyl groups mutually deviate from the coordination plane in opposite directions. The stability of the fused 5,5-membered chelate ring formed by the S528-03C528-04S ligand seems to overcome the steric hindrance. Derivatives were prepared by replacement of the chloride ion with iodide, diethyldithiocarbamate, 4-tert-butylpyridine, or tri-n-butylphosphine, and characterized spectroscopically. The S528-05C528-06S-fused chelate ring was maintained in these derivatives.     

Synthesis of a C60 complex withN,N,N′,N′-tetramethyl-p-phenylenediamine and its crystal structure

The complex of fullerene C₆₀ withN,N,N,N-tetramethyl-p-phenylenediamine (TMPD) was synthesized and studied by X-ray analysis.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1285–1287, May, 1996. 1996     

Spectroscopy of the complexation of polybutadienyl- and polypentadienyllithium by ditertiary bases—II. 1,2-Dipiperidinoethane and N,N,N′,N′-tetraethylethylenediamine

The influence of 1,2-dipiperidinoethane (DPE) and tetraethylethylenediamine (TEEDA) on the butadienyl- and pentadienyllithium active centres has been examined by NMR and electronic spectroscopy. The effect of DPE on the butadienyllithium species differs from that of TEEDA in that the magnitudes of the ¹H shifts are considerably smaller at any given [base]:[lithium] ratio. The trans conformation was found to be the preferred structure of the active centres in the presence of diamines. The electronic spectra of these dienyllithium active centres in the presence of these bases exhibited new peaks with γ_max at 323–325 nm where the maximum influence of either base was seen at [base]:[lithium] ratios of ca two.     

Two New C—glucoside Flavonoids from Leaves of Crataegus pinnatifida Bge. var. major N.E.Br.

Two new C-glucoside flavonoids,namely 8-C-β-D-（2″-O-acetyl) glucofuranosyl apigenin and 3″-O-acetylvitexin, were isolated from beaves of Crataegus pinnatifida Bge. var. major N.E.Br.Their structures were elucidated by the spectroscopic means and chemical evidence.     

Stoichiometry, Thermodynamics and Kinetics of Host–Guest Interactions between Cryptand C222 and Iodine in 1,2-Dichloroethane. Formation of a C222.I+ Inclusion Cryptate

The host–guest molecular complexationreaction between cryptand C222 and iodine has beenstudied spectrophotometrically in 1,2-dichloroethanesolution. The resulting 1 : 1 and 2 : 1 (I₂ to C222)complexes were formulated as (C222 I⁺)I^-and (C222 I⁺)I₃ ^-, respectively. Theenthalpy and entropy of the complex formationreactions were evaluated from the temperaturedependence of the formation constants. The resultingcomplexes are both enthalpy and entropy stabilized.The spectrophotometric, NMR, conductometric andpotentiometric results emphasize that the complexesare positive iodine cryptates. The rate constants forthe formation and proton-assisted dissociation of the(C222 I⁺)I₃ ^- complex at varioustemperatures and the corresponding activationparameters were evaluated. Based on the results thusobtained, possible pathways for the complexationreaction are proposed.     

Calorimetric study of the solubilization of ethylenediamine,N,N-dimethylaminoethylamine and N,N,N′,N′-tetramethylethylenediamine by reversed AOT micelles

Distribution constants and standard enthalpies of transfer of ethylenediamine (en), N,N-dimethylaminoethylamine (dmen) and N,N,N,N-tetramethylethylenediamine (tmen) partitioned between n-heptane and water containing reversed sodium bis(2-ethylhexyl) sulfosuccinate (AOT) micelles as a function of the molar concentration ratio R (R=[water]/[AOT]) were evaluated by a calorimetric method. The results show that en, dmen and tmen molecules, solubilized in the reversed micelles, are distributed between the micellar aqueous core and the micellar palisade layer. An analysis of the thermodynamic parameters of the partition process demonstrates the peculiar solvent properties of the water containing reversed AOT micelles.     

Thermodynamic characteristics of protolytic equilibria of hexamethylenediamine-N,N,N′,N′-tetraacetic acid

The heats of dissociation of betaine groups of hexamethylenediamine-N,N,N′,N′-tetraacetic acid (H₄L) at 298.15 K and the ionic strengths of 0.1, 0.5, and 1.0 (KNO₃) were determined by direct calorimetry. The standard thermodynamic characteristics of the ptotolytic equilidria of H₄L were calculated using the results from thermochemical and potentiometric measurements made under identical test conditions.     

Coordination compounds of nickel with trithiocyanuric acid. Part IV. Structure of [Ni(pmdien)(ttcH)] (pmdien = N,N,N′,N′,N′′-pentamethyldiethylenetriamine,ttcH3 = trithiocyanuric acid)

Ni^II mixed-ligand complexes of compositions [Ni(pmdien)(ttcH)] (1), [Ni(baphen)₂(ttcH)] · 4H₂O (2), [Ni-(dpa)(ttcH)(H₂O)] (3), [Ni(cyclam)(ttcH)] · 2H₂O (4), [Ni(hexaa)](ttcH) (5) and [Ni(hexab)(ttcH)] · 2H₂O (6), (baphen = 4,7-diphenyl-1,10-phenanthroline, dpa = 2,2-dipyridylamine, cyclam = 1,4,8,11-tetraazacyclotetradecane, hexaa = 1,3,6,9,11,14-hexaazatricyclo[12.2.1.1^6,9]-octadecane, hexab = 1,8-dimethyl-1,3,6,8,10,13-hexaazacyclotetradecane) have been prepared and characterized by means of i.r., u.v.–vis. spectroscopies and magnetochemical measurements. The redox properties of the complexes were studied by cyclic voltammetry. The crystal and molecular structure of [Ni(pmdien)(ttcH)] was determined. The nickel atom is penta-coordinated by three N atoms of pmdien, and by S and N atoms of trithiocyanurate(2–) anion.     

Synthesis of benzoindoloquinolizines via a Cu(I)-mediated C–N bond formation

An effective synthesis of the multi ring-fused benzoindoloquinolizines has been accomplished by Cu(I)-mediated and MW-assisted C–N_amide bond formation of benzo[a]quinolizin-4-ones. The deamination of tetrahydro-2H-pyrido[2,1-a]isoquinolines was also studied and was found to give benzoquinolizines. The benzo[a]quinolizin-4-ones were prepared based on the annulations of C-1 substituted 3,4-dihydroisoquinolines and azlactones.     

Structural studies of cyclic ureas: 1. Enthalpies of formation of imidazolidin-2-one and N,N′-trimethyleneurea

A thermophysical and thermochemical study has been carried out for crystalline imidazolidin-2-one and N,N′-trimethyleneurea [tetrahydropyrimidin-2(1H)-one]. The thermophysical study was made by differential scanning calorimetry, d.s.c., in the temperature intervals between T = 268 K and their respective melting temperatures. Several solid–solid transitions have been detected in imidazolidin-2-one. The standard (p^° = 0.1 MPa) molar enthalpies of formation, at T = 298.15 K, for crystalline imidazolidin-2-one and N,N′-trimethyleneurea [tetrahydropyrimidin-2(1H)-one], were determined using static-bomb combustion calorimetry. The standard molar enthalpies of sublimation, at T = 298.15 K, for the two compounds were derived from the variation of their vapour pressures, measured by the Knudsen effusion method, with the temperature. These two thermochemical parameters yielded the standard molar enthalpies of formation of the two cyclic urea compounds studied in the gaseous phase at T = 298.15 K. These values are discussed in terms of molecular structural contributions and interpreted on the bases of the “benzo-condensed effect” and of the ring strain of imidazolidin-2-one.