bluuebunny/crossref_metadata_2025 huggingface dataset:
Ba(OH)2 as the Catalyst in Organic Reactions‐Part VI Influence of Catalyst Structure and Basicity in the Alcohol Condensation of Acetone
Authors: Barrios J. , Marinas J. M. , Sinisterra J. V.
Published: September 2010

The aldol condensation of acetone in solid‐liquid system catalyzed by a family of barium hydroxide catalysts has been carried out. The C‐200 is more active and selective than the commercial barium hydroxide in the aldol condensation of acetone. The structure of the catalysts were analyzed by IR, TGA, TDA and X‐ray powder diagrams. The basic sites of the catalysts were titrated by benzoic acid (BA). The crystalline structure and the number of basic sites are related to the catalytic activity. Ba(OH)2.H2O is shown to be the active compound.
Thallium (I), Uranyl (II) and Vanadyl (II) complexes of 1–2‐amino‐3 Hydroxy Butanoic acid‐a Polarographic Study
Authors: Saxena R. S. , Parikh Reshma D.
Published: September 2010

Complexation of Tl+1, UO22+ and VO+2 with 1–2‐amino‐3 hydroxy butanoic acid (AHB) has been studied polarographically in aqueous media. The reduction has been found to be reversible and diffusion controlled involving a one electron transfer process in the case of Tl+ and a two electron transfer process in the case of UO22+ and VO2+. The plot of ‐E1/2 vs‐log Cx yielded a straight line indicating the formation of a 1:1 complex in the case of UO22+ and VO+2 and hence the method of Lingane was adopted for the evaluation of coordination number and stability constants. However, in the case of Tl+ the plots of potential vs concentration data revealed the formation of 1:1 and 1:2 (M:L) complexes, whose stability constants were determined by employing DeFord and Hume's method.
X‐ray Diffraction Analysis of New ring‐Enlargement Derivatives of Penicillin G: 2‐thia‐3,3‐Dimethyl‐4R‐(t‐Butyloxycarbonylmethylene) Carboxylate‐5,7‐Diaza‐6‐Oxo‐8r‐Phenylacetamido‐Bicyclo‐1r‐[3,3,0]Octane and 2‐Thia‐3,3‐Dimethyl‐4R‐(t‐Butyloxycarbonylmethylene) Carboxylate‐5,7‐Diaza‐6‐oxo‐7‐Benzoyl‐8R‐Phenylacetamido‐Bicyclo‐1 R‐[3,3,0]octane
Authors: Declercq J. P. , van Meerssche M. , Marchand‐Brynaert J.
Published: September 2010

The X‐ray structures of the compounds were solved by direct methods from diffractometer data.

4d: 2‐thia‐3,3‐dimethyl‐4R‐(t‐butyloxycarbonylmethylene)carboxylate‐5,7‐diaza‐6‐oxo‐8R‐phenylacetamido‐bicyclo‐1R‐[3,3,0]octane, C22H29N3O6S, monoclinic, space group P21; cell dimensions: a=13.625(6), b=8.344(3), c=10.656(3)Å, β=95.18(3)°; V=1206.4(8)Å3, Dx=1.28 gcm−3 for Z=2. 1646 measured and 1098 observed reflections. Final R=0.067.

5d: 2‐thia‐3,3‐dimethyl‐4R‐(t‐butyloxycarbonylmethylene)carboxylate‐5,7‐diaza‐6‐oxo‐7‐benzoyl‐8R‐phenylacetamido‐bicyclo‐1R‐[3,3,0]octane, C29H33N3O7S. H2O, monoclinic, space group P21; cell dimensions: a=11.074(4), b=6.255(1), c=21.801(6)Å, β=92.49(3)°; V=1508.5(8)Å3; Dx=1.29 gcm−3 for Z=2.2257 measured and 1836 observed reflections. Final R: 0.071.

Small but significant changes of bond lengths in the diaza pentagonal cycle are probably due to the benzoyl substituent.
Synthesis of α‐(2‐Hydroxy‐2, 2‐Dimethylethyl)‐ω‐Methyl‐, and of α ω‐Bis (2‐Hydroxy‐2,2‐Dimethylethyl) Polyethylene Glycol
Authors: van Den Berge L. , Tavernier D. , Anteunis M.
Published: September 2010

The transformation of the end groups of polyethylene glycol to the O‐ethoxycarbonylmethyl derivative 2 is described, using either a base‐catalysed reaction with ethyl bromoacetate or an acid‐catalysed reaction with ethyl diazoacetate. Compound 2 was reacted with methyllithium or methylmagnesium iodide to yield the α, ω title compounds. The end hydroxyl grouping of polyethylene glycol monomethyl ether was similarly transformed. Yields, experimental convenience and eventual side reactions are discussed.
The Determination of Cadmium in Sewage Sludge of Domestic Origin by Means of ion Exchange Combined with ICP‐AES and Ion Exchange Combined with GF‐AAS
Authors: Taylor P. D. P. , Desmet B. , Dams R.
Published: September 2010

This paper describes the determination of Cd in a sample of sewage sludge of domestic origin. The analysis result obtained was used by the European Community Bureau of Reference (BCR) for the certification of the Cd content in this sample (BCR N° 144). The combination of the low Cd content and the difficult environmental matrix made the certification especially arduous. In this study, a suitable sample digestion and chemical separation method is described. Inductively Coupled Plasma‐Atomic Emission Spectrometry (ICP‐AES) and Graphite Furnace‐Atomic Absorption Spectrometry (GF‐AAS) are both used as means of detection. The values obtained are compared with the certified value as well as with two other values stemming from nuclear analytical techniques which are quasi unaffected by contamination.
Remote‐Controlled System for the Production of [1‐11C] Palmitic Acid
Authors: Goethals P. , Slegers G.
Published: September 2010

A semi‐automated production unit is developed for the routine production of [1‐11C] palmitic acid via carbonation of n‐pentadecyl magnesium bromide with 11CO2. The labeled compound is synthesized to study the myocardial metabolism by means of positron emission tomography. Chemical, radiochemical and pharmaceutical control showed that the product is suitable for human i.v. administration. In 35 min 40 to 60 mci of [1‐11C] palmitic acid are produced in a final isotonic solution of 12 ml.
Accurate Analytic Fitting of Pixe Spectra
Authors: Maenhaut W. , Vandenhaute J.
Published: September 2010

The computer program AXIL has been modified so that it describes complex PIXE spectra in a more accurate way. The modifications include a new representation of the absorption (detection efficiency) term, a non‐linear energy calibration, and a sum peak modeling routine. The new version (AXIL‐84) is described in some detail and several examples are given to illustrate its present performance.
The Voltammetric Behaviour of the System Bi(III)/Bi(Hg) IN 4M HClO4
Authors: Bogaert M. , Temmerman E. , Kiekens P. , Verbeek F.
Published: September 2010

The voltammetric behaviour of Bi(III)/Bi(Hg) in 4M HClO4 has been studied with the aid of DC polarography and cyclic voltammetry. The reduction mechanism is complex. The electrochemical reduction is preceded by a homogeneous chemical reaction and the three‐electron reaction has to be considered as three successive one‐electron transfers. Quantitative results relative to as well the electrochemical as the chemical reaction are obtained.
Études Structurales En Série Helicenique. IV. Structures Du Fluoro‐1 Heptahelicene C30H17F Et Du Cyano‐17 Fluoro‐1 Heptahelicene C31H16Fn
Authors: van Meerssche M. , Declercq J. P. , Soubrier‐Payen B.
Published: September 2010

The structures of the title compounds have been determined by X‐ray single crystal diffractometry.

The crystal data are as follows: 1F‐|7|helicene C30H17F, triclinic, space group p1, a=8.696(2), b=16.547(6), c=14.377(4)Å, α=74.01(3), β=100.44 (2), γ=91.59(3)°, Z=4; 1F‐17CN‐|17|helicene C32H16FN, monoclinic, space group C2, a=48.980(17), b=9.678(6), c=17.456(6)Å, β=90.69(3)°, Z=16. The helicenic fragment of the molecules are very similar in structure to heptahelicene itself.
Nitration de Pyridinobenzotetraazapentalenes
Authors: Maquestiau A. , Flammang‐Barbieux M. , Vilain E.
Published: September 2010

The orientation specificity for nitration reaction of [3,2‐b] pyridino and [2,3‐b] pyridino‐1,3a,6,6a− and 1,3a,4,6a‐tetraazapentalenes is discussed.
Chimio‐ et Régiosélectivités de la Cycloaddition de Diarylnitrilimines sur la Thieno(2,3‐c)Pyridine
Authors: Fathi Toufik , An Nguyen Dinh , Schmitt Gérard , Vebrel Joël , Laude Bernard
Published: September 2010

Diaryinitrilimines 2 react regiospecifically on the CN double‐bond of thieno(2,3‐c) pyridine 1 to give in a first step a cycloadduct 3 DANI 2 react regiospecifically on the enaminic double‐bond of the cycloadduct 3 to give the diadduct 4.
Reversible Ring‐Opening Reaction of a Triazolobenzodiazepine, Triazolam, in Acidic Media
Authors: Jiménez R. M. , Alonso R. M. , Vicente F. , Hernández L.
Published: September 2010

The hydrolytic reaction of Triazolam in acidic solution at room temperature was studied spectrophotometrically. The reversible azomethine bond cleavage reaction of Triazolam took place and an open‐ring compound was in equilibrium with a closed‐ring compound. Kinetic studies indicate that the hydrolysis reaction is first order with respect to proton concentration. The indirect determination of acid‐dissociation constant was carried out from the kinetic data. The pKa value (2.19) is similar to the one obtained (2.26) from spectrophotometric acid‐base studies. The shift of peak potential of the Triazolam obtained by differential pulse polarography also showed the acid hydrolysis of the compound.
Crystal Structure and Conformation of Short Linear Peptides: Part III: Glycyl‐L‐Leucyl‐L‐Tyrosine 2.5 Hydrate Dimethylsulfoxide Solvate
Authors: Wu S. , Tinant B. , Declercq J. P. , van Meerssche M.
Published: September 2010

C17H25N3O5 (CH3)2SO2 5H2O, Mr = 474.6, triclinic, P1, a = 11.990(4), b = 12.380(11), c = 9.342(3)Å, α = 83.92(5), β = 79.99(3), γ = 84.60(6)Å, V = 1241(1)Å1, Z = 2, Dx = 1.27 gcm−3, MoKa, λ = 0.71069 Å, μ = 1.38 cm‐1, F(000) = 1020, T = 291K, R = 0.056 for 2854 observed reflections. The title peptide (GLT) adopts an anti‐parallel pleated‐sheet conformation, very similar to that found in the copper (II) complex of this peptide(1). This confirms that the conformation of this peptide is affected only very slightly by the solvatation. The Leu side‐chain of molecule B takes a conformation characterized by X1 = ‐178°, X21 = 152° and X22 = ‐85°, which is only observed in D‐Leu residue.
Two‐Dimensional Nuclear Magnetic Resonance Study of the Conformation of The Tetrapeptide Z‐His‐Trp‐Ser‐TyrOH
Authors: Zhang Weiguo , Anteunis Marc J. O. , Borremans Frans A. M.
Published: September 2010

Two‐dimensional (2D) NMR homonuclear correlation (COSY, Relayed COSY and Delayed COSY) and 2D NOESY techniques were applied to obtain the unambiguous assignments of the individual protons of Z‐His‐Trp‐Ser‐TyrOH, a component tetra‐peptide of LH‐RH, in deuterated dimethyl sulfoxide solution (DMSO). The observed 2D‐NOE connectivities, the chemical shift and coupling data, and the amide NH chemical shift temperature gradients are consistent with a random coil backbone conformation.
Transformation of Sucrose ‐ Re‐Examination of Octamolar Tosylation of Sucrose
Authors: Sharma N. K. , Norula J. L. , Anteunis Marc J. O.
Published: September 2010

Octamolar tosylation of sucrose with p‐toluenesulfonyl (tosyl)chloride has been re‐examined under different conditions to obtain octa‐O‐tosyl sucrose as a single entity. It was observed that tosylation of sucrose with 8 moles of tosyl chloride in pyridine at 0°C, ‐5°C and ‐15°C afforded octa ‐O‐tosyl sucrose, hepta‐O‐tosyl sucrose, hexa‐O‐tosyl sucrose and penta‐O‐tosyl sucrose respectively in varying amounts. The products obtained were purified by column chromatography and the structures of the chromatographically pure tosyl esters were confirmed by high resolution 1H NMR spectra of their respective acetates.
Synthèse et Étude de RMN1H en Présence de l'Eu (fod)3 des Pyrazolo[1,5,4‐ef] Benzodiazepine ‐1,5 Ones‐6(1)
Authors: Benchidmi M. , Essassi E. M.
Published: September 2010

Condensation of β‐Ketoesters with 7‐aminoindazoles have been examinated. The structure of pyrazolo [1,5,4‐ef] benzodiazepin ‐6‐ ones, obtained from ethylacetylacetate have been established by mass spectrometry and by 1H NMR in presence of Europium (fod)3.
Simple Preparations of Some Hydantoins of Phenylalanine and α‐MePhe and Their Chiral Stability During N3‐Alkylation. A Route to the Synthesis of Chiral Amines
Authors: Anteunis M. J. O. , Spiessens L. , De Witte M. , Callens R. , Reyniers Fr.
Published: September 2010

Preparations of chiral‐pure hydantoins derived from L‐Phe and L‐α‐MePhe are re‐visited. A one step quantitative route for 5‐benzyl‐5‐methyl hydantoin is obtained by melting α‐MePhe with ureum. L‐Phe‐hydantoin could not be alkylated at N‐3 with conservation of the chirality at C‐5. Diastereomers resulting from asymmetric alkyl groupings implanted at N‐3 can be separated by crystallization in aqueous medium. The N‐3 alkylated hydantoins can be hydrolyzed in high yields with Ba (OH)2. This allows the preparation of enantiomeric pure amines such like 2‐methylbutylamine and 2‐hydroxypropylamine via N‐3 alkylation of the chirally‐stable hydantoin of α‐MePhe followed by enantiomeric resolution and hydrolysis.
Potentiometric Investigation of the Complexes Formed by Citraconate in Water at Ionic Strength I=1 and I=3
Authors: Bouserie Frank L. G. , Thun Harry P.
Published: September 2010

A potentiometric study is made at 25°C of the dissociation of citraconic acid in aqueous sodium perchlorate solutions of ionic strength 1 and 3.
Crystal Structure and Conformation of Short Linear Peptides: Part VII: L‐Leucyl‐L‐Tyrosyl‐L‐Leucine Monohydrate
Authors: Wu S. , Declercq J. P. , Tinant B. , van Meerssche M.
Published: September 2010

C21H33N3O5H2O, Mr = 425.52, monoclinic, P2, a = 13.387(5), b = 15.452 (7), c = 13.198(5) Å, β = 115.74(3)°, V = 2459(2)Å3, Z = 4, Dx = 1.15 g. cm−3, MoKα, λ = 0.71069 Å, μ = 0.91 cm−1, F (000) = 920, T = 291K, R = 0.071 for 2348 observed reflections. The two independent molecules have quite different conformations. An antiparallel‐chain pleated sheet structure is observed at Tyr residue of molecule A and at Leu(2) residue of molecule B, characterized by (ϕ, Ψ) angles of (‐130°, 121°) and of (‐134°, 140°) respectively. A poly‐Gly‐II conformation is observed at Leu(2) level of molecule A and at Tyr level of molecule B with (ϕ, Ψ) values of (‐114°, 159°) and of (‐83°, 137°) respectively. The Leu(2) side chain of molecule A takes an unusual conformation with (X1, X21, X22) angles of (‐74°, 48°, ‐172°). The other side chains have normal conformations.
Trans‐Diaqua‐Bis[Dimethylglyoximato(1‐)‐N, N′] Cobalt(III) Perchlorate: Crystal Structure and Local Disordering Effects
Authors: Pyckhout W. , Lenstra A. T. H. , Tyrlik S. K.
Published: September 2010

[Co(C4H7N2O2)2 (H2O)2]ClO4, Mr = 424.7, C2/c, a = 21.344(5), b = 5.980(2), c = 13.707(2)Å, β = 113.08(1)°, V = 1609.5(1)Å3, Z = 4, Dx = 1.744 Mg m−3, Mo Kα, λ = 0.71069Å, μ = 1.28 mm−1, F(000) = 872, room temperature, wR = 0.068 for 975 reflections.

The perchlorate ion is disordered. Models assuming completely free rotation and rotation around one Cl‐O vector could be rejected. A description using occupancy factors for the O atoms proved satisfactory. The Co is octahedrally coordinated by 4N atoms in the equatorial plane and by two axial H2O ligands, the Co‐O (water) = 1.900(3)Å. Inequalities in the bond lengths of a dimethylglyoximato ligand are in accord with expected trends when one of the oxime groups is protonated and the other is negatively charged. Two short intramolecular hydrogen bridges are observed with O—O distances of 2.53 Å and 2.60 Å.
Molecular Structure Analysis of Benzamide Neuroleptics and Analogs. XII: (Exo)‐2, 3‐dimethoxy‐N‐[8]‐(Phenylmethyl)‐8 ‐AZA ‐Bicyclo [3.2.1] Oct ‐ 3 ‐ YL] Thiobenzamide, Hydrochloride
Authors: Collin S. , Baudoux G. , Evrard G. , Durant F.
Published: September 2010

C23H28N2O2S.HCLI2 (two molecules in the asymmetric unit), Mr = 866.0, monoclinic, P21/c, a = 21.523(1), b = 13.274(1), c = 15.679(2) Å, β = 94.19(1)*, V = 4467.54 Å3. Z = 4, Dc = 1.29 g·cm−3, Cu Kα, λ = 1.54178 Å, μ = 24.34 cm−1. F(000) = 1840, final Rw = 0.05 for 3799 observed reflections (1 ≥ 2.5 σ(1)). Bond distances and angles show a delocalization of the Π orbitals in the thioamide moiety without significant delocalization to the phenyl ring. Comparison with a very active analog, the tropepride, suggests that the decrease of the title compound antipsychotic activity is due to the lack of a strong intrabenzamidic hydrogen bond which is present in the active benzmides.
Calculation of Aluminum Speciation in the Presence of Inorganic Complexing Agents
Authors: Courtyn E. , Nagels M. , Vandecasteele C. , Yu Z‐Q. , Dams R.
Published: September 2010

Equilibrium concentrations of inorganic complexes of Al in solutions containing varying amounts of sulfate and fluoride at different pH values are calculated. Although the proposed model is simplified and does not take into account the precipitation of aluminum hydroxide, it shows clearly which are the dominating species in the pH range from 3 to 6.
Détermination des Constantes D'Acidité des Acides Mercapto‐2 Pyridinecarboxylique‐4 et Mercapto‐4 Pyridinecarboxylique‐2
Authors: Thunus L. , Lejeune R. , Delarge J.
Published: September 2010

UV and potentiometric studies on 2‐(or 4−) mercapto‐4‐(or‐2−) pyridinecarboxylic acid are made. Estimation of aromatic and non aromatic species is done by derivative spectroscopy and acidity constants are found. Aromaticity in pyridine derivatives are discussed.
Synthèse de 2,3‐Dihyoro‐7H‐Pyrazolo [3,4‐b] Pyridine‐3‐Ones
Authors: Maquestiau A. , Vanden Eynde J.‐J.
Published: September 2010

Reactions between 5‐anilino‐2,4‐dihydro‐2‐phenyl‐3H‐pyrazol‐3‐one and β‐dicarbonyl compounds yield 2,3‐dihydro‐2,7‐diphenyl‐7H‐pyrazolo [3,4‐b] pyridin‐3‐ones, products which were not described previously.

Structures of bicyclic derivatives obtained from unsymmetrical β‐dicarbonyl precursors were determinated by means of 1H NMR and IR data.
Hydrodenitrogenation of Decahydroquinoline Over Carbon‐Supported Transition Metal Sulfide Catalysts
Authors: Sudhakar C. , Eijsbouts S. , De Beer V. H. J. , Prins R.
Published: September 2010

The catalytic properties of the first, second and third row transition metal sulfides supported on activated carbon (TMS/C) were investigated for the hydrodenitrogenation of decahydroquinoline in micro‐autoclaves at 50 bar total pressure and at 623 K or 653 K. Excluding vanadium sulfide, the first row TMS/C catalysts had very low activity and showed no periodic trend. On the other hand, second and third row TMS/C catalysts were quite active and showed volcano‐type periodic trends, with maxima at Rh and Ir sulfides respectively. These periodic trends were very similar to those observed earlier for the TMS/C catalysts in the hydrodenitrogenation of quinoline and in the hydrodesulfurisation of thiophene.
An In‐Situ Mössbauer Study on the Formation and Stability of the Fe‐Mo‐S Phase in Carbon‐Supported Iron Molybdenum Sulfide Hds Catalysts
Authors: Ramselaar W. L. T. M. , Crajé M. W. J. , Gerkema E. , De Beer V. H. J. , van Der Kraan A. M.
Published: September 2010

The transition of an oxidic FeMo/C precursor into the actual active sulfide catalyst is studied by means of in‐situ Mössbauer spectroscopy. It is found that the composition of the sulfided catalyst is influenced by the sulfidation method applied. A correlation between the spectral contribution of a mixed Fe‐Mo sulfide (Fe‐Mo‐S) phase and the activity for thiophene HDS is demonstrated.
Correlation of 15N NMR shifts with calculated charge densities in nucleic bases derived from purine
Authors: Zeegers‐Huyskens Th.
Published: September 2010

The 15N NMR shifts of the different nitrogen atoms of purine and adenine derivatives are correlated to their π‐charge densities.
H/D isotope effect in γ‐irradiated C10H22/C10D22 mixtures at 4 K deduced by studying dimeric products by gas chromatography
Authors: Tilquin B.
Published: September 2010

The dimer products formed upon γ‐irradiation at 4 K of n‐decane‐d22 doped with 20% n‐decane‐h22 have been examined by means of capillary GLC coupled with mass spectrometry. Analysis of the results indicates that protiated alkyl radicals are selectively formed. This confirms the data obtained by radiolysis at 77 K. The selective abstraction of hydrogen from a C‐H bond on the solute molecules by the attack of D atoms which are formed by the radiolysis, occurs at 77 K. However, at 4 K, data from IWASAKI suggest an other explanation. The primary process is not selective but conversion of deuterated to protiated alkyl radicals takes place at 200 K.
Direct determination of selenium in whole blood with electrothermal A. A. S. and deuterium arc background correction
Authors: Deschuytere M. A. , Robberecht H. J. , Deelstra H.
Published: September 2010

Direct determination of selenium in human whole blood is carried out using graphite furnace atomization absorption spectrometry. Interferences of inorganic ions, especially iron, are eliminated by using a molybdenum coated furnace and a L'vov platform. Different oxydation states of selenium revealed the same results. By comparison with hydride generation atomic absorption spectrometry and fluorimetry after wet acid digestion it can be concluded that the described procedure resulted in accurate values for selenium concentrations in small volumes of human whole blood.
Isolation of factor a (virginiamycin M1) and factor B (mixture of Vs1 and Vs4) from a commercial feed additive formulation
Authors: Sharma N. K. , Hosten N. , Anteunis M. J. O.
Published: September 2010

Virginiamycins S (mixture of VS1 and VS4) next to Virginiamycin M (VM1) were isolated by a simple selective extraction method followed by recrystallization, starting from a commercially available formulation, marketed as feed additive.
Carboxymethyloximation of keto substrates. A useful grafting procedure applied on virginiamycin factors A & B
Authors: Anteunis M. J. O. , Callens R. , Sharma N. K.
Published: September 2010

Virginiamycins M1 and S1 (factors A & B) were converted to their corresponding carboxymethyl oximes 1 & 2 in quantitative yields. 1 was further conjugated with tryptophan methyl ester to obtain derivative 3 in high yield by using BOP‐Cl as coupling reagent. The compounds 1, 2 & 3 were fully characterized by I. R. and 1H NMR spectra. Carboxymethyloximation seems to be a practical strategy for the preparation of conjugates of biologically active ketonic substrates.
Structure Du Kotschyioside, Saponoside Nouveau Isole De Aspilia Kotschyi (Sch. Bip.) Oliv
Authors: Kapundu Mpuza , Penders André , Warin Roger , Delaude Clément , Huls Robert
Published: September 2010

The major component of the saponin mixture from leaves of Aspilia Kotschyi (Asteraceae) has been isolated as a peracetylated and cristalline derivative. Its structure has been established essentially by NMR spectroscopy including two dimensional NMR and shown to be : 3β‐0‐(4 deoxy‐α‐hex‐4 enopyranosyluronic acid) 3 1 α‐L‐rhamnopyranosyl, 28‐0‐β‐D‐glucopyranosyl oleanolic acid.

The name “Kotschyioside” is proposed for this new saponin.
Structure of 4‐(N′‐Pivaloyl)‐D(L)‐Phenylalanyl‐D (L)‐Perhydro‐4H‐1, 4‐Thiazine‐3‐(N‐Methyl) Carboxamide Methanol Monohydrate in the Crystalline State
Authors: Wu S. , Tinant B. , Declercq J. P. , van Meerssche M. , Borremans F. A. M. , Anteunis M. J. O.
Published: September 2010

A crystal of the homochiral isomer of N‐Piv‐Phe‐(γS) Pec‐NHMe. CH3OH. H2O is subjected to an X‐ray diffraction analysis. C20H29N3O3S. CH3OH. H2O, Mr = 441.58, triclinic, P1, a = 12.981(2), b = 9.939(1), c = 11.345(1) Å, α = 75.05(1)°, β = 63.15(1)°, γ = 71.46(1)°. Z = 2, V = 1226.8(3) Å3, Dx = 1.20 g. cm−3, CuKα, λ = 1.54178 Å, μ = 14.31 cm−1, F (000) = 476, T = 291K, R = 0.058 for 3875 observed reflections. The data reveal a molecular conformation with all trans amide bonds, in an “open form” (ϕ1, ϕ1, ϕ2, ϕ2 = 123.8°, −81.9°, 120.4°, −23.1°) without intramolecular hydrogen bond, stabilized in a crystal environment of strong intermolecular H‐bonding.
Étude Sterochimique En Série Perhydrocyclohepta |b| Furanne
Authors: Dolmazon R. , Albrand M. , Henry R.
Published: September 2010

Configurations and probable conformations for the cis ‐ perhydrocyclohepta |b| furan‐3‐ols and perhydrocyclohepta |b| furan‐3‐ones obtained in this study are inferred from their 1H‐NMR and IR spectra. The energy difference between cis‐ and trans‐perhydrocyclohepta |b| furan‐3‐ one is virtually negligible.
Hexachlorodimedone: Ring opening and intramolecular substitution of halogen. Preparation of γ,δ‐Diketoacids and Esters
Authors: De Buyck L. , De Pooter H. , Schamp N.
Published: September 2010

The β‐dione system of 2, 2, 4, 4, 6, 6‐hexachloro‐5, 5‐dimethyl‐1, 3‐cyclohexanedione (1) is cleaved by weak base in methanol or aqueous organic solvent. The intermediate enolate ester 3a (resp. the carboxylate) is competitively protonated or chlorinated by 1. Protonation was made exclusive with added acetic acid, while chlorination was made exclusive in the presence of chlorine or hypochlorite.

The reactions in methanol were applied to prepare the δ‐ketoesters 3 (hexachloro) and 5 (heptachloro) in excellent yields. Haloform degradation of 5 (NaHCO3 in methanol) afforded dimethyl 2, 2, 4, 4‐tetrachloro‐3, 3‐dimethyl‐1, 5‐pentanedioate (6) while 3 was easily cyclised to the stable enolether 4 by the same reagent.

In aqueous solvent (acetic acid, dioxan or isopropanol) the ring opening of 1 was followed by a remarkably rapid intramolecular substitution of halogen by the carboxylate function, giving rise to y‐butyrolactones and the corresponding γ,δ‐diketoacids 8 and 14.
Investigation of some neba ‐ perchlorate electrodes for use in physicochemical measurements
Authors: De Poorter J. , Thun Harry P.
Published: September 2010

Liquid membrane electrodes sensitive to perchlorate anions are prepared by using solutions of N‐ethylbenzothiazole‐2,2′ azaviolene perchlorate in 1,2‐dichlorobenzene or β,β′‐dichlorodiethylether. The behaviour and the analytical possibilities of these electrodes were examined at 25°C.
Novel oxidation of 1,2‐Dibenzylhydrazines with carbon tetrachloride
Authors: Kano Kunio , Anselme Jean‐Pierre
Published: September 2010

1,2‐Dibenzyhydrazines are cleanly oxidized to the corresponding ω,ω'‐azotoluenes by carbon tetrachloride; carried out under phase‐transfer conditions in the presence of sodium carbonate, the new reaction provides a clean, inexpensive, nearly quantitative route to the azotoluenes.
Synthesis and preliminary pharmacology* of the rigid dehydroxylated etorphine analogue 4,5α‐epoxy‐α,α,17‐trimethyl‐6α,14α‐etheno‐isomorphinan‐7α‐methanol (chemistry of opium alkaloids, part XXVI**)
Authors: Linders J. T. M. , Lie T. S. , Maat L.
Published: September 2010

The synthesis of 4, 5α‐epoxy‐α, α, 17‐trimethyl‐6α, 14α‐ethenoisomorphinan‐7α‐methanol (6) via hydrogenolysis of the corresponding 3‐(1‐phenyltetrazol‐5‐yl) ether (5) is described. The etheno bridge was retained under the conditions used. Preliminary pharmacology of the title compound showed strong analgesic potency.
Hydrogenolysis Mechanism of Five Membered Heteroatom Rings Over MoS2‐Based Catalysts
Authors: Delmon B. , Dallons J.‐L.
Published: September 2010

This paper describes a concerted mechanism for the hydrogenolysis of the carbon‐heteroatom bond of thiophene, pyrrole and furan (and homologs) on molybdenum or tungsten sulfided catalysts (promoted by Co, Ni or Fe). The five‐membered rings would adsorb by a π bond on a coordinatively unsaturated Mo (or W), with their heteroatom (S, N or O) interacting, as electron acceptors, with the sulfur atoms of two vicinal sulfhydryl groups. After a 2,3 semi‐hydrogenation, a concerted mechanism would bind the hydrogen atoms of the sulfhydryl groups to the carbon atoms in the 1 and 4 positions, while the hydrogen atoms initially attached to these 1 and 4 carbon atoms would form H2S with the thiophenic sulfur (or NH3 or H2O). The mechanism explains most published features of the reactions and explains the special selectivity of sulphide catalysts, especially with furan.
Simple and efficient deoxygenation of heteroaromatic n‐oxides using TiCl4/SnCl2
Authors: Kaczmarek Lukasz , Malinowski Marek , Balicki Roman
Published: September 2010

Various unfunctionalized heteroaromatic N‐oxides are efficiently deoxygenated to the corresponding bases under mild conditions by treatment with the novel reagent TiCl4/SnCl2.
Fundamental questions about entropy I. Definitions: Clausius or Boltzmann?
Authors: Huyskens P. L. , Siegel G. G.
Published: September 2010

The expression of Boltzmann S = k In W differs in principle from the entropy as defined by Clausius because it is not strictly extensive. It becomes strictly extensive when the number W of all possible molecular arrangements is replaced by a normalized value  ‐ N A N B… where 1) the standardized probability  that characterizes one particle A is the same for all the NA particles; 2) the possibilities for the particles of a given kind are considered separately from the possibilities of the particles of another kind. In contrast to W that characterizes the whole system,  is a product of as many factors as there are particles of different kinds in the different phases. Examples are given for the entropy of mixing of mixed crystals and the entropy of expansion of real gases.
Non‐fourier transform data processing in nuclear magnetic resonance spectroscopy
Authors: Dereppe J. M.
Published: September 2010

Fourier transform of time domain data into spectra is not always an ideal process. Other techniques such as the maximum entropy or modeling methods offer certain advantages : better resolution and better sensitivity obtained at the price of increased computation time.
Fragmentation et Isomérisation de Pyrazolides en Pyrolyse‐Éclair Sous Vide
Authors: Maquestiau A. , Bienfait I. , Ben Abdelouahab F. B. , Flammang R.
Published: September 2010

Flash‐vacuum pyrolysis of 1‐benzoylpyrazole 1 at ca 800° under low pressure conditions affords mainly 2‐phenylfuran 2 and phenylallene 3 as indicated by a real‐time analysis using tandem mass spectrometry and by preparative scale experiments. Although 1‐acetylpyrazole [8] loses quasi exclusively ketene, isomerization into (a) C‐acylated isomer(s) is also detected by mass spectrometry.
Application de la Technique RMN de Transfert de Saturation Pour Mesurer L'Activité Enzymatique dans des Muscles Lisses de Mytilus Edulis
Authors: Schanck A. , Baguet F.
Published: September 2010

The unidirectional fluxes between phosphoarginine and ATP were determined by 31P NMR saturation transfer on in vitro preparation of anterior byssus retractor muscles of Mytilus edulis. The forward and reverse fluxes are comparable and it is deduced that the arginine kinase reaction is near equilibrium for these resting muscles.
Reaction du fluoroborate du benzoyl‐2 dihydro‐1,2 isoquinaldonitrile avec les esters α,β‐ethyleniques cas des esters acrylique, fumarique et maleique. Competition entre les reactions de cycloaddition [3+2] et [4+2]
Authors: Schmitt Gérard , Laude Bernard , Vebrel Joël , Rodier Noël , Theobald François
Published: September 2010

In all reactions studied up to the present time with olefinic esters, the Reissert salts have given only the Diels‐Alder adducts. By adding triethylamine to the reaction medium, we have found evidence for competing 1,3‐dipolar cycloaddition and Diels‐Alder reactions in three cases: acrylic, fumaric and maleic esters. The regiochemistry of the 1,3‐dipolar cycloadducts was determined chemically and from spectroscopic (IR, NMR) data. The stereochemistry of the cycloadducts was specified by radiocrystallographic studies. The reaction is assumed to proceed by a concerted mechanism.
Diels‐Alder Adducts From 4‐O‐Acetyl‐6‐Demethoxy‐N‐Formyl‐β‐Dihydro‐N‐Northebaine With Methyl Vinyl Ketone and Nitroethene (Chemistry of Opium Alkaloids, Part XXIX)
Authors: Linders J. T. M. , Lipman P. J. L. , Saly E. , Lie T. S. , Maat L.
Published: September 2010

Reductive epoxy ring scission of 6‐demethoxy‐N‐northebaine (5) with zinc and potassium hydroxide gave a 85:15 mixture of 6a and its non‐conjugated isomer. Formylation with triethyl orthoformate, followed by acetylation with acetic anhydride in the presence of 4‐(dimethylamino)pyridine gave a 4:1 mixture of the title compound 6c and its non‐conjugated isomer in 80% overall yield.

Diels‐Alder reaction of 6c with methyl vinyl ketone afforded a 2:1 mixture of 7β‐acetyl‐and 8β‐acetyl‐6β, 14β‐ethenomorphinan 7 and 8a. Cycloaddition of nitroethene yielded the 8β‐nitro‐6β, 14β‐ethenomorphinan 8b as major product.

N‐Demethylation of 2b, the 4‐O‐phenyl ether of 6‐demethoxy‐β‐dihydrothebaine (2a), with diethyl azodicarboxylate failed to give the N‐norcompound.
Extraction‐Spectrophotometric Determination of Cadmium With 2‐(5′‐Ethyl‐1′,3′,4′‐Thiadiazolyl‐2′‐Azo)‐4‐Methoxyphenol
Authors: Reyes J. P. , Trujillo J. P.Pérez , Sosa Z. , Arias J. J.
Published: September 2010

A new extraction‐spectrophotometric method for the determination of cadmium, based on the formation of the complex Cd(II): 2‐(5′‐ethyl‐1′,3′,4′‐thiadiazolyl‐2′‐azo)‐4‐methoxyphenol into benzene is developed (ϵ=37,800 l. mol−1. cm−1 at 610 nm).
A Conformational Study of Some Secondary 2‐Furanecarbothioamides
Authors: Jagodzinski Tadeusz S. , Dziembowska Teresa M. , Szczodrowska Barbara
Published: September 2010

Analysis of the UV, IR and 1H‐NMR spectra and of the dipole moments indicated nonplanarity of the secondary thioamides derived from 2‐furanecarboxylic acid and a free rotation of the thioamide group around the C‐C bond. Quantum‐mechanical calculations of the s‐cis ⇆ s‐trans conformational equilibrium and of the dipole moments were carried out by the CNDO/2 method for the N‐methylthioamides of 2‐furane‐ and 2‐thiophenecarboxylic acid.
FVP Interconversion of 1‐, 2‐and 3‐Tritylindazoles
Authors: Pérez Jorge D. , Yranzo Gloria I. , Elguero José , Claramunt Rosa María , Garcerán Rafael
Published: September 2010

FVP of 1‐1, 2‐2 and 3‐tritylindazole 3 was carried out at 300 and 400°C. The experimental results show that 3 isomerizes to 1 and 2; 2 isomerizes to 1 at 300°C and 1 remains unchanged at 300 and at 400°C gives 2 and by‐products. These transformations represent novel isomerizations in heterocyclic chemistry.
Protonation Behaviour of Diphenylamine in Water‐Dimethyl‐Formamide (Dmf) Mixtures
Authors: Murali Rao D. Mohan , Kalidas C.
Published: September 2010

The thermodynamic dissociation constant (pK) of diphenylamine (DPA) ion in Water‐DMF mixtures of various compositions at 25°C has been determined by a spectrophotometric method. The pK is found to decrease and passes through a minimum around 60 wt % DMF. The variation of pK has been examined in terms of the variation of Gibbs transfer energies of various species involved in the equilibrium.
Synthèse Dans La Série Des Phenanthridines I. Recherches Des Conditions Éxperimentales Optimales Dans La Préparation D'Alkyl‐6 Phenanthridines Et De Leur Sel
Authors: Lion C. , Boukou‐Poba J. P. , Charvy C.
Published: September 2010

The synthesis of 6‐alkylphenanthridines and their corresponding salts has been developed. The well known “biphenyl method” has been studied. Acylation of o‐aminobiphenyl is achieved by an acid or the corresponding anhydride or acyl chloride. Cyclization of the intermediate o‐acylamidobiphenyl has been studied in various conditions (solvents, temperature…). Quaternization has also been accomplished: new 6‐alkylphenanthridinium salts have been prepared in good yields.
Soluble Substituted Silane High Poymers
Authors: Miller R. D.
Published: September 2010

High molecular weight polysilane derivatives represent a new class of radiation sensitive polymers with very unusual electronic properties for which a number of potential applications have been discovered. This talk will touch briefly on polymer synthesis and characterization, mechanisms for the photo chemical decomposition and describe certain selected applications.
Les Membranes De Permeation Gazeuse: Caractéristiques Et Principales Applications Industrielles
Authors: Deschamps A. , Avrillon R. , Mileo J.‐C.
Published: September 2010

This paper is an introduction, for membranes non specialists, to the different aspects of gas separation by membranes.

It summarizes the fundamentals of gas permeation, the problems of polymer selection and membrane manufacture. Then the main industrial applications are reviewed.
Oxidation of Aldehydes to α,β‐Unsaturated Aldehydes via α‐Chloroaldimines
Authors: Kimpe Norbert De , Stevens Christian
Published: September 2010

The oxidation of aldehydes to α,β‐unsaturated aldehydes has been performed by a sequence of reactions involving conversion into aldimines, chlorination at the α‐position to form α‐chloroaldimines, base‐induced dehydrochlorination and hydrolysis. The four‐step transformation can be executed without isolation of the intermediates. This method has been applied to the synthesis of an artificial flavor, i.e. 2‐butyl‐3‐phenylpropenal.
A Serendipitous Synthesis of Bis(α‐Cyano‐4‐Nitrostyrene‐β‐yl) Ether
Authors: Roose B. , Anteunis M. J. O. , Tavernier D.
Published: September 2010

The title compound is obtained by reacting α‐cyano‐4‐nitrostyrene‐β‐ol with dicyclohexylcarbodiimide (molar ratio 2:1) at room temperature in tetrahydrofuran solvent.
The Active Ester α‐Cyano‐4‐Nitrostyrene‐β‐yl Acetate is also the Captodative Olefin 2‐Acetoxy‐1‐Cyano‐1‐(4‐Nitrophenyl)Ethene. Synthesis of 2,4‐bis(4‐Nitrophenyl)Pent‐2‐Enedinitrile
Authors: Roose B. , Anteunis M. J. O. , Tavernier D.
Published: September 2010

The new compounds (α‐cyano‐4‐nitrostyrene‐β‐yl) phenyl sulfide and Z‐2,4‐bis(4‐nitrophenyl)pentenedinitrile (BPD) were synthesized by reacting α‐cyano‐4‐nitrostyrene‐β‐yl acetate with benzenethiolate and 4‐nitrobenzyl cyanide anion respectively. BPD is a carbon acid, pKa = 3.5 in MeOH/H2O (2:1); solutions of BPD anion have an intense blue colour (VIS absorption in methanol: λm = 582nm, ε = 60000 L mol−1cm−1). −1H and −13C NMR spectra of BPD and BPD anion are discussed. The formation of minute amounts of BPD, observed during the N‐acylation of α‐amino acid hydrochlorides/Et3N with α‐cyano‐4‐nitrostyrene‐β‐yl esters, could be traced to the presence, in the α‐cyano‐4‐nitrostyrene‐β‐ol used to prepare the active ester, of ca 1% 4‐nitrobenzyl cyanide, which is partially deprotonatable by Et3N. The possibility that the α‐cyano‐4‐nitrostyrene‐β‐ol ejected in the acylation step would generate 4‐nitrobenzyl cyanide, and hence BPD, by deformylation, with e.g. water or amines as acceptor of the formyl group, could be disproved. The formation of BPD is avoided by replacing Et3N by the weaker base N‐methylmorpholine.
Étude de la coupure des liaisons o‐si d'éthers siliciés du type en présence d'agent nucléophile et/ou d'acide
Authors: Giral L. , Madit N. , Montginoul C. , Sagnes R. , Schué F.
Published: September 2010

We report a study on the hydrolytic instability of the oxygen‐silicon bond of the following compounds: p‐tert‐butyldimethylsilyloxytoluène, p‐triméthylsilyloxytoluène and poly(p‐triméthylsilyloxystyrène). The instability occurs in an acidic media: HCl, H−2SO4, CF3CO0H, BF3 or in presence of a salt: KPF6, KAsF6, KSbF6, NaBF4, [CH3(CH2)3]4NF, [CH3(CH2)3]4NBF4, [CH3(CH2)3]4NPF6, [CH3(CH2)3]4N AsF6, [CH3(CH2)3]4NSbF6. A mixture containing both an acid and a salt from those previously discussed can also be used.

A number of representative examples is presented. The tert‐butyldimethylsilylether derivatives are much more stable than the trimethylsilylethers. It is shown that the rate of reaction is dependent on the nucleophilicity of anion used in these salts. This simple procedure undoubtedly extends the scope for a preparation of organosilicon resists.
−1H and −13C NMR Study of C‐16 OYL and C‐17 Acyl Vinblastine Derivatives at 300 MHz Using 2‐D NMR Experiments
Authors: Bhushana Rao Kandukuri S. P. , Cornet Jeanine , Bruyn André De
Published: September 2010

In the present study we describe: (1) the −13C NMR study of two compounds resulting from the amidation of the ester at C‐16 of 17‐deacetyl‐vinblastine and (2) the −1H and −13C NMR study of one compound resulting from the acylation (or esterification) at C‐17 of vinblastine. For the assignment of the −13C NMR resonances, DEPT and −13C, −1H‐heteronuclear shift correlated experiments were performed.
Some Simple Conjugates of Virginiamycin and their Bioactivity
Authors: Di Giambattista M. , Sharma N. K. , Anteunis M. J. O.
Published: September 2010

Derivatives of the native antibioticum Viginiamycin S1 (3) conjugated at the pipecolic acid oxo position (5–12) have been prepared and their bioactivity tested together with some earlier prepared congeners (4, 13–16). Some of these show promising activities (e.g. 9, 15 and 16).
Intramolecular Diels‐alder Reaction with Furan‐Diene and Allene‐Dienophile. Application in Steroid Synthesis
Authors: Missiaen Patrick , De Clercq Pierre J.
Published: September 2010

In connection with the synthesis of corticosteroids the potential of adducts 4a and 4b, which are obtained in the intramolecular Diels‐Alder reaction of furan‐allene 3, is studied. The hydrogenation of 4a, followed by double bond isomerization, results in enone 9a, which was found to be a useful substrate both for 1,4‐addition and for dissolving metal reduction.
Étude expérimentale de la structure d'une flamme NH3/NO/AR
Authors: Bian J. , Vandooren J. , Tiggelen P. J. Van
Published: September 2010

An ammonia‐nitric oxide‐argon flat flame has been stabilized at low pressure (54 torr) and analyzed by using the molecular beam sampling technique coupled with the mass spectrometric analysis (MBMS).

The signal intensities of stable (NH3, NO, N2, H2O, H2, N2O et Ar) as well as of unstable (NH2 et H) species have been recorded throughout all the flame. The temperature profile was measured by using a PtRh6%‐PtRh30% coated thermocouple. The absolute mole fraction profiles of the measured species have been established by an appropriate calibration.

A preliminary examination of the flame structure shows the ammonia oxidation leads to the formation of NH2 radicals and to the occurrence of H, O and OH radicals concentrations much lower than those observed in an NH3/O2/Ar flame. The reaction of NH2 with NO is the key process for the formation of N2 as well as for the increase of the total radical concentration in the flame.
Contribution of GC‐MS Analyses to the Determination of the Self‐Ignition Mechanism of 1,4‐Dioxane in Chlorine
Authors: Battin F. , Dzierzynski M. , Marquaire P. M. , Côme G. M. , Baronnet F.
Published: September 2010

An experimental investigation in a conventional static apparatus of gas phase reactions between 1,4 dioxane and chlorine has permitted to observe auto‐ignitions above 100°C at subatmospheric pressure and to map out the limits of reaction zones in a pressure‐temperature diagram. To achieve a better understanding of the reaction mechanism leading to these auto‐ignitions, we have performed an experimental investigation of the slow reaction in a flow system; GC‐MS analyses were used to identify the reaction products. Our results show that at high conversion, 1,4‐dioxene is the dominant reaction product; we also obtain smaller amounts of chlorinated by‐products of 1,4‐dioxane. The results of this investigation are used to build a tentative reaction scheme accounting for the experimental features of the reaction.
Étude expérimental et modèlisation de flammes de prémélangé
Authors: Pauwels J.‐F. , Sochet L.‐R.
Published: September 2010

The aim of flame structure analysis is to set up a chemical mechanism which describes the flame chemistry satisfactorily.

Two ways can be used. The first one compares the experimental and modelled mole fraction profiles. In the second one, the experimental net rates are compared with the balance of formation and destruction rates obtained from the postulated mechanism.

These methods are applied to study different methanol‐air flames (0.82<ø<1.50). A reaction path analysis is used to interpret a reduced model which gives a good description of the experimental phenomena.
The Influence of Data Truncation Upon Signal, Noise and Resolving Power in Residual Controlled Translation Searches
Authors: Petit G. A. , Lenstra A. T. H.
Published: September 2010

For structures in the space group P1 first and second moments are derived of the density distribution function P(R2) of the residual R2 corresponding to the one correct (signal) and to all the completely incorrect translations (noise) of the search fragment in function of the size of the fragment and the intensity moments of the structure at hand. This allows us to investigate the resolving power of R2‐controlled translation searches based on the property that R2 values related to incorrect translations are Gaussian distributed.

The results are made structure independent by averaging over all observable structures. It could be concluded that any data truncation reduces the resolving power, but that the elimination of small E2obs values is least detrimental. A method is given to estimate ”a priori“ the minimum size of the search fragment which allows a successful translation search.
Localization of Mn2+ Ions in Zeolites Y Derived from Computer Simulation of Experimental EPR Spectra
Authors: Zawacki M. , Gutsze A. , Kornatowski J.
Published: September 2010

A correlation between the shape of electron paramagnetic resonance spectra and the localization of Mn2+ ions in zeolite Y partially exchanged with Mg2+ and Ca2+ ions has been studied.

The spectra have been interpreted based on computer simulation of EPR powder spectra of paramagnetic ions of electron spin S = 5/2 and nuclear spin I = 5/2. This interpretation resulted in differentiation of the experimental EPR spectra into 4 types corresponding with localization of Mn2+ ions in the structure of zeolite Y.
Macroheterocycles: Synthesis and applications as complexing agents, enzyme mimics and catalysts
Authors: Kellogg Richard M. , Kaptein Bernard , Buter J.
Published: September 2010

Two types of systems are discussed. The first one is derived from lutidine, which either is condensed with two equivalents of a ketone or ketone equivalent or is subjected to nucleophilic substitution by stabilized carbanions via lutidine‐2,6‐dibromide. The resulting non‐macrocyclic systems (podands) on further conversion form derivatives that wrap themselves selectively about metal ions. The Zn2+ complexes mimic the active site zinc of liver alcohol dehydrogenase. The other type of compound is a thiamacrocycle. Excellent synthetic routes to these sulfur analogs of crown ethers have been devised and the chemistry ‐ complexations of metal ions, reaction with BH3 ‐ has been explored.
Nucleoside Analogues with a 1,4‐Dioxane, 1,4‐Oxathiane or 1,4‐Oxazine Ring Structure as the Carbohydrate Fragment
Authors: van Aerschot Arthur , Janssen Gerard , Herdewijn Piet
Published: September 2010

Pyrimidine and purine nucleoside analogues with a 1,4‐dioxane, 1,4‐oxathiane or 1,4‐oxazine ring structure have been prepared from the corresponding dimesylated seconucleosides by treatment with either sodium hydroxide, sodium sulfide or primary alkylamines.
Hydrogen Bonds in Ethenoisomorphinan‐7α‐Carboxamides Studied by Molecular Modelling (Chemistry of Opium Alkaloids, Part XXXIV
Authors: Cappon J. J. , Linders J. T. M. , Maat L.
Published: September 2010

Within the scope of the study of structure‐activity relationships of opioids, we examined some conformational aspects of the rotation of the 7α‐substituent in ethenoisomorphinan peptides. Using molecular mechanics (MMX88) we have determined the relative contribution of two possible intramolecular hydrogen bonds to the orientation of the 7α‐substituent in a model compound (7). The minimum conformation found shows great resemblance in the morphinan skeleton with an X‐ray structure of a morphinan peptide studied previously. The results indicate that the orientation of the 7α‐substituent will be largely defined by hydrogen bonding. The hydrogen bond between the amide hydrogen and the 6‐hydroxyl oxygen (B) causes a greater stabilization than the competing bond between the 6‐hydroxyl hydrogen and the 7α‐carbonyl oxygen (A) in case of the model compound.
Haloaldehyde polymers XLVIII., Optical activity of diastereomeric bornyloxy terminated aldehyde unimers
Authors: Hatada Koichi , Ute Koichi , Nishimura Tohru , Xi Fu , Vogl Otto
Published: September 2010

Bornyl oxide initiated, acetate endcapped unimers of trifluoroacetaldehyde, trichloroacetaldehyde and tribromoacetaldehyde were prepared and their optical rotations were determined. The value of the optical rotations of the unimers was correlated to the bulk size of the trihalomethyl group and they were compared to those of the unimer of formaldehyde and bornyl acetate. The bornyloxy terminated trihaloacetaldehydes consist of 2 diastereomeric unimers. In the cases of the chloral and bromal unimers they have been isolated. One diastereomer of the trichloroacetaldehyde unimers was crystallized and its absolute configuration was established by x‐ray spectroscopy.