Two Efficient Syntheses of Protected 4‐Deoxy‐D‐lyxo‐hexose (4‐Desoxy‐D‐mannose)

The formation of four differently protected 4‐deoxy‐D‐lyxo‐hexose derivatives 7, 8, 12, and 14 is described. In the first procedure, a nucleophilic displacement of the allylic mesylate 4 by hydride was combined with a highly stereoselective osmylation of olefin 6 to afford diol 7. In the second radical procedure, tributyl tin hydride was substituted by the cheap and environmentally friendly hypophosphorous acid as a hydrogen donor in the reduction of xanthate 13 to 4‐deoxy lyxo‐hexose 14.     

Chemical constituents from Epimedium koreanum Nakai and their chemotaxonomic significance

In this study, 21 compounds were isolated from the aerial parts of Epimedium koreanum Nakai, including 6 phenols (1–5 and 10), 4 lignans (6–9) and 11 flavonoids (11–21). The chemical structures of those isolates were established after extensive one-and two-dimensional nuclear magnetic resonance and mass spectroscopy analyses. This is the first report of compounds 2, 3, 4 and 9 in E. koreanum and of compounds 5 and 7 in the family Berberidaceae. The chemotaxonomic significance of the isolated compounds is discussed.     

Substitutions- und Additionsreaktionen an Spiro-oxiranen

Nucleophilic substitution at the spiro carbon atom as well as the CH₂-group takes place with spiro-oxiranes1,6 and7, whose spiro carbon atom bear electron withdrawing substituents. In some cases by elimination of formaldehyde a transformation to the corresponding reductone systeme (5,11,16) is observed. In other cases, e.g. with tertiary amines, betaines (2,9,12) are formed, which by elimination of the base rearrange to dioxolenes (3,10). Addition of polar reagents like aryl isocyanate or chloral leads to ring expansion of the threemembered ring to form the five ring systems17,18,20,22 or24.

Herrn emer. o. Univ. Prof. Dr.Erich Ziegler, Institut für Organische Chemie, Karl-Franzens-Universität Graz, mit besten Wünschen zur Vollendung des 70. Lebensjahres gewidmet.     

Umsetzung von phosphororganischen CH-aciden Verbindungen mitSchiffschen Basen in Gegenwart saurer und basischer Katalysatoren, 7. Mitt.: Umsetzung von Estern der p-Brom-benzylphosphonsäure in Gegenwart von Natriumamid und Aluminiumchlorid

The esters of p-bromobenzylphosphonic acid (1) react withSchiff bases (2) in the presence of 0.5 mols of NaNH₂ in ether at –33° and 10° as well as in liquid ammonia to give esters of 2-arylamino-2-aryl-1-(p-bromophenyl)-ethanephosphonic acids (3 and4) in 33–78% yields. In many cases and particularly in liquid ammonia and in ether at 10° the olefin5 is formed along with the adducts3 and4. In a low extent1 a and2 a react also in the presence of AlCl₃ to form3 a in 20% yield. The stereochemistry of the reaction is studied by thin layer chromatography, and the reactivity of1 is compared with that of the esters of benzylphosphonic acid.     

A mesitylene-bridged bis-benzimidazolyl ligand and six metal coordination compounds

The mesitylene-bridged bis-benzimidazolyl ligand 1,3-bis(benzimidazol-1′-yl-methyl)mesitylene (L) and six metal complexes, [Cu₉L₆(OH)₇Cl₈] (1), [Co₂L₄(NO₃)(H₂O)₂](NO₃)₃ (2), [Zn₂L₂Cl₄] (3), [CdL₂(NO₃)₂]_n (4), [MnL(L_A)(CH₃OH)]_n (5), and [CoLCl₂]_n (6) (L_A = terephthalate), have been prepared and characterized. Complex 1 is a football-like cluster formed by six Ls, nine Cu(II) ions, eight chlorides, and seven hydroxides, in which the size of the football is about 13.9 × 15.4 Å. Complex 2 contains a cage-like ball formed by four Ls and two Co(II) ions, in which the external and internal sizes of the ball are about 12.2 × 14.6 Å and 6.5 × 10.7 Å, respectively. In this complex, one nitrate is fixed in the middle of the cage through two Co–O bonds. The 24-membered metallomacrocycle of 3 is formed by two Ls and two Zn(II) ions. In 4, 2-D layers with 48-membered metallomacrocycles are formed via Ls and Cd(II) ions. In 5, L and terephthalate ions (L_A) participate in coordination with Mn(II) to afford 2-D network layers. The 1-D polymeric chain of 6 is formed via L and Co(II) chloride moieties. In the crystal packing of 1–6, 2-D supramolecular layers and 3-D supramolecular frameworks are formed via intermolecular weak interactions, including hydrogen bonds, π–π interactions, and C–H?π contacts. The conformations of metal complexes from L are described. Additionally, the fluorescence emission spectra of L and 1–6 are reported.     

Experimental evidence for the breakdown of conventional elasticity in smectics A

Abstract

Grinstein and Pelcovits have shown that anharmonic terms in the ‘microscopic’ elastic free energy lead to a qualitative change in the macroscopic elastic expressions describing the equilibrium behaviour of smectic A liquid crystals. In particular, they showed that the elastic moduli B(ω = 0,q) and K ₁ (ω = 0,q) vanish and diverge, respectively as In(q) for small wavevector q. In the dynamical case (ω ≠ 0), as predicted by Mazenko, Ramaswamy and Toner, the influence of anharmonicity is more dramatic: some viscosities diverge as 1/ω We present in this paper a finite ω version of the non-linear hydrodynamics of smectic A and what we believe to be the first experimental evidence of the decrease of the layer compressional modulus B(ω, q), at low frequency ω and wavevector q.     

Chlorodiphenyltin(IV) and triphenyltin(IV) complexes of N-alkylated 2-amino-1-cyclopentene-1-carbodithioic acids: synthesis, spectroscopic characterization and X-ray studies

Four new complexes, [Ph₃Sn(isopropylACDA)] (1), [Ph₂SnCl(isopropylACDA)] (2), [Ph₃Sn(secbutylACDA)] (3), and [Ph₂SnCl(secbutylACDA)] (4), have been prepared from reaction between N-alkylated 2-amino-1-cyclopentene-1-carbodithioic acids (ACDA) with Ph₂SnCl₂ and Ph₃SnCl in 1:1 ratio. All complexes are characterized by FTIR, multinuclear NMR (¹H, ¹³C, and ¹¹⁹Sn) and mass spectrometry. In all complexes, the S–H proton has been removed and coordination takes place through the carbodithioate moiety. The ¹¹⁹Sn NMR data are consistent with five coordination of tin atom in solution. Complexes 2, 3, and 4 have also been confirmed by single X-ray crystallography. All three crystals are triclinic with space group P − 1. In complexes 2 and 4, the geometry around tin atom is distorted trigonal bipyramidal while in 3 the geometry is in between distorted tetrahedral and trigonal bipyramid. In all three structures, ligands are asymmetrically coordinated to tin atom. In addition, crystal structures are further stabilized by N–H···S hydrogen bonding.     

Structural features and N-H…O and O-H…O hydrogen-bonded supramolecular frameworks in 2-methylanilinium hydrogen DL-malate hydrate, 4-methoxyanilinium and 4-methylanilinium hydrogen DL-malate salts

In the crystal structure of 2-methylanilinium hydrogen DL-malate hydrate (I), an additional water molecule is present in asymmetric unit. In the crystal structures of 4-methoxyanilinium hydrogen DL-malate (II) and 4-methylanilinium hydrogen DL-malate (III), the hydrogen malate anions exhibit configurational disorder with major component occupy S-configuration and minor component occupy R-configuration provided both (II) and (III) are prepared from a racemic mixture of DL-malic acid. In crystal structures of compounds (I)–(III), the hydrogen malate anions and anilinium cations from O-H…O and N-H…O hydrogen bonds which exhibit interesting supramolecular frameworks. In compound (I), the N-H…O and O-H…O hydrogen-bonded anionic-cationic framework form two-dimensional hydrophilic and hydrophobic layers in which the lattice water molecules are embedded in hydrophilic layers. However, in crystal structures of (II) and (III), the hydrogen DL-malate anions form two-dimensional anionic substructure through O-H…O hydrogen bond, in which the anilinium cations are anchored through N-H…O hydrogen bonds.

     

Notiz zur Darstellung von 4-Hydroxy-6-methyl-5,6-dihydro-2H-pyran-2-on

Meldrum's acid (2) is acylated by diketen affording the acylMeldrum's acid3. In aqueous bicarbonate its 3-oxogroup is selectively reduced by sodium tetrahydroborate giving the alcohol4, which readily undergoes cyclization in refluxing dioxane leading to the title pyrone7. Under identical conditions3 produces the pyrone6 with the pyrone carboxylic acid5 as intermediate.

     

Beiträge zur Stereochemie der Additionsreaktionen an 3,4,5,6-Tetrahydropyridin-1-oxide. 2. Mitt.

4-tert-Butyl-3,4,5,6-tetrahydropyridine-1-oxide (1) and 6-butyl-3,4,5,6-tetrahydropyridine-1-oxide (2) were prepared and isolated in their monomeric forms. In many aprotic solvents these compounds are converted into their dimers. The main product in both cases is the addition product of identical enantiomers. In the case of compound1 a very small amount of an addition product of the optical antipodes is also formed, which is the thermodynamically most stable isomer. In contrast, compound2 yielded an addition product of the optical antipodes in larger amounts, with a thermodynamically less favourable structure. These dimerizations are solvent dependent, reversible and sensitive to steric hindrance.

     

Indium-containing heterofullerenes and their η5-π-complexes

The molecular and electronic structure of hypothetical metallofullerenes In₅C₅₅ (1a) and In₁₀C₆₀ (2a) were simulated by the MNDO/PM3 method. Formally, heterofullerene1a is obtained from the C₆₀ cluster by replacement of the carbon atoms at α-positions relative to one of the pentagons by In atoms, and cluster2a is obtained from the C₇₀ cluster by replacement of the carbon atoms framing the polar pentagons of this fullerene by In atoms. Along with clusters1a and2a, their η⁵-π-complexes ln(η⁵-1a (1b) and ln₂(2η⁵-2a) (2b) with one (1b) and two (2b) exohedral In atoms coordinated to the pentagons (pent ^*) isolated by In atoms were also studied. The energies of the In—pent ^* bonds in1b and2b are approximately equal to 104 kcal mol⁻¹. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 880–883, May, 1998.     

Synthesis,characterization, and biocide activity of new dithiocarbamate-based complexes of In(III), Ga(III), and Bi(III) – Part III

In this work, we describe the syntheses, characterization, and antifungal activity of [In{S₂CNR(R¹)}₃] (1), [Ga{S₂CNR(R¹)}₃] (2), [Bi{S₂CNR(R¹)}₃] (3), [In{S₂CNR(R²)}₃] (4), [Ga{S₂CNR(R²)}₃] (5), and [Bi{S₂CNR(R²)}₃] (6) {R?=?Me; R¹?=?CH₂CH(OMe)₂; and R²?=?2-methyl-1,3-dioxolane}. All complexes have been characterized using infrared and ¹H and ¹³C spectroscopy, and the structures of 1, 3, 4, and 6 have been authenticated by X-ray diffraction. The In(III)–dithiocarbamate bonding scheme depicts a distorted octahedral with asymmetric In(III)–S bonds and S–In–S angles. A pentagonal bipyramid is observed for the corresponding Bi(III) complexes with intermolecular Bi–S associations through the lone pair of electrons. The antifungal activities of 1–6 have been screened against Aspergillus niger, Aspergillus parasiticus, and Penicillium citrinum, and the results have been compared with those of nystatin and miconazole nitrate, as control drugs.     

Lipolytic effect of compounds isolated from leaves of mulberry (Morus alba L.) in 3T3-L1 adipocytes

In this study, 19 known compounds were isolated from mulberry (Morus alba L.) leaves. The lipid accumulation inhibitory activity of the isolated compounds was investigated. Compounds 4 and 12 showed good anti-adipogenic activity based on 3T3-L1 adipocytes with values of 36.6 ± 9.0 and 34.7 ± 4.0%, respectively. In addition, compounds 3, 6 and 15 showed significant inhibitory activity with values from 15.4 to 21.2% and compounds 2, 8–9 and 17–18 exhibited weak activity with values ranging from 2.1 to 10.7% at a concentration of 40.0 μM. These results show the potentiality that mulberry leaf is an excellent inhibitory phytochemical source against lipid accumulation.     

Indium(III) complexes containing bithiazole derivatives,chloride, methanol,and dimethyl sulfoxide: X‐ray studies,spectroscopic characterization,and thermal analyses

[In(dm4bt)Cl₃(MeOH)]?·?0.5dm4bt (1) (dm4bt is 2,2′‐dimethyl‐4,4′‐bithiazole) and [In(4bt)Cl₃(MeOH)] (2) (4bt is 4,4′‐bithiazole) were prepared from the reaction of 4,4′‐bithiazole and 2,2′‐dimethyl‐4,4′‐bithiazole with InCl₃?·?4H₂O in methanol, respectively. [In(4bt)Cl₃(DMSO)] (3) was also prepared from recrystallization of 2 in DMSO. These complexes were characterized by IR, UV‐Vis, ¹H NMR, ¹³C{¹H} NMR, and luminescence spectroscopy and their structures were studied by single‐crystal X‐ray crystallography. The thermal stabilities of 1 and 3 were studied by thermogravimetric and differential thermal analyses.     

Vanadium(V) Complexes of O,N,O-Donor Tridentate Ligands Containing the {VVO(OMe)}2+ Unit: Syntheses,Structures and Properties

Abstract

Syntheses, characterisation and properties of two complexes containing the oxovanadium(V) methoxide unit have been described. Deprotonated benzoylhydrazones of 2–hydroxy–5–methoxy‐benzaldehyde (H₂bhsOMe) and 2–hydroxy–5–chlorobenzaldehyde (H₂bhsCl) were used as coligands. Crystal structures of both the complexes were determined. In solid state one of them is a dinuclear species [VO(bhsOMe)(OMe)]₂ (1) whereas the other one is a mononuclear complex [VO(bhsCl)(OMe)(HOMe)](2). The dinegative ligands coordinate the metal ions via phenolate–O, imine–N and deprotonated amide–O atoms. In 1, the metal ions of two square pyramidal VO(bhsOMe)(OMe) units share the methoxide groups to form a dinuclear species. The oxygen of a methanol molecule completes the hexacoordination of the metal centre in 2. In each of the two distorted octahedral VO₅N moieties of 1 the bridging methoxide oxygen and in that of 2 the methanol oxygen is trans to the corresponding oxo group. Both the complexes are redox active. The VO³⁺ to VO²⁺ reduction potentials (vs Ag/AgCl) of 1 and 2 are observed at ?0.25 and ?0.04 V, respectively. The band positions in the electronic spectra and the redox potentials reflect the influence of the substituents present on the ligands.     

Coumarin-based symmetrical bisamide as fluorescent and colorimetric probes for copper ions

Coumarin-based new symmetrical bisamide 1 has been designed and synthesised. The bisamide 1 fluorometrically recognises Cu²⁺ in CH₃CN containing 0.06% DMSO by exhibiting an increase in emission upon complexation. In comparison, the isomeric structure 2 also reports the selectivity for Cu²⁺ under identical condition by showing an opposite mode of emission. In addition, Cu²⁺ gives rise to a change in colour of the solution of 1, which is clearly visible to the naked eye.     

‘Thermodynamic,structural and morphological studies on liquid-crystalline blue phases’ by H. Stegemeyer,Th. Blümel,K. Hiltrop,H. Onusseit and F. Porsch

Abstract

In the review article on cholesteric blue phases by Stegemeyer et al. [1], table 3 lists [100] as the second largest BPI facet and the largest BPII facet. If such is the case, then, it is important to realize that it is unlikely the body centred cubic phase of BPI has O⁸(I4 ₁32) symmetry and the simple cubic phase of BPII, O²(P4₂32) symmetry [2–4].     

Structure and properties of an oxalato-bridged dinickel(II) complex with a tetraazamacrocycle bearing an aminomethyl pendant arm, 5-aminomethyl-5R(S),12R(S)-dimethyl-1,4,8,11-tetraazacyclotetradecane

The oxalato-bridged dinickel(II) complex with the title ligand, [Ni₂(L ^a H)₂(μ-ox)](ClO₄)₂·2H₂O (1), was prepared and its structure was determined by X-ray crystallography, as well as that of the monomeric nickel(II) complex, [Ni(L ^a H)ox]ClO₄·3H₂O (2). In Complexes 1 and 2, the ligand, L ^a , is folded along the N(4)–Ni(1)–N(11) axis. The antiferromagnetic coupling between the two nickel(II) centers in 1 was revealed and the coupling constant, J?=??17.4?cm^?1, and g?=?2.11 were estimated. It was found that the oxalato-bridged dimer 1 was readily converted to the mononuclear cis-nickel(II) complex [NiL ^a (OH₂)](ClO₄)₂ (3a), in basic aqueous solution. In [NiL ^a (CH₃CN)]I₂ (3b), which was derived from 3a, the aminomethyl pendant arm is coordinated to the Ni(II) ion and L ^a is folded along the N(1)–Ni(1)–N(8) axis.     

The Conformation of Sterically Congested Seven-Membered Rings Containing Tetracoordinate Germanium(IV): A First X-Ray Crystallographic Structure Determination

The X-ray crystallographic analysis of 6,6-dimethyl-2,4,8,10-tetra-tert-octyl-dibenzo[d,f][1,3,2]dioxagermepin, 1 is reported. In the solid-state conformation of 1, the dihedral angle about the C─C sp²-sp ² σ bond connecting the two aryl rings is 50.1°. The observed C₂ symmetry in the solid-state conformation of 1 is consistent with the previously suggested solution conformation.     

Zur Reaktivität 4,5-ungesättigter 3-Oxoalkannitrile gegenüberMichael-Acceptoren

The 3-oxonitrile1 as well as the 2-benzylidene-3-oxonitrile4 on reaction with benzylidenemalononitrile or malononitrile, respectively, afford 2-amino-4H-pyran derivative3 in high yield. In contrast, reactions of1 and4 with ethyl benzylidenecyanoacetate (6) or ethylcyanoacetate, respectively, predominantly lead to a carbocyclic compound, which is also obtained as main product on attempted condensation of1 with benzaldehyde. Based on spectroscopic data, structure5 is proposed for the novel compound; its formation is interpreted in terms of piperidine-catalysed addition of1 to4 and subsequent intramolecularMichael addition. Reaction mechanisms for the conversion of1 and6 or4 and ethylcyanoacetate to5 are discussed.

Herrn Univ. Prof. Dr. Dr. h c.K. Kratzl zum 70. Geburtstag gewidmet.