Synthèse et propriétés biologiques des pyrazolo〚4,3-c〛triazolo〚4,3-a〛〚1,5〛benzodiazépines

The addition of carbon disulfide to 3(5)-N-〚methyl (ethyl)-2-aminophenyl amino-5(3)-phenylpyrazole 3 (4) afforded 10-methyl (ethyl)-3-phenylpyrazolo〚4,3-c〛 〚1,5〛 benzodiazepine-4-thione 7 (8). These compounds reacted with alkyl halides and acetylhydrazide or benzoylhydrazide, to afford new heterocyclic systems: pyrazolo 〚4,3-c〛 triazolo〚4,3-a〛-1,5-benzodiazepines 15–18. Biological properties of compounds 8, 9, 16 and 17 have been evaluated.     

Synthèse de nouvelles 7 (5)-〚benzimidazol-2-yl〛méthyl-2 (7)-méthyl-1,2,4-triazolo〚1,5-a〛(〚4,3-a〛)pyrimidines

Condensation of 4-hydroxy-6-methyl pyran-2-one 2 with 3-amino-1,2,4-triazole 1 in refluxing alcohol afforded 5-alkoxycarbonylmethyl-7-methyl-1,2,4-triazolo〚1,5-a〛pyrimidines and their isomers 5-alkoxycarbonylmethyl-7-methyl-1,2,4-triazolo〚4,3,-a〛pyrimidines 4. Reaction of hydrazine hydrate with compounds 4 and 5 yielded the corresponding hydrazid acids 6 and 7. Condensation of o-phenylenediamines 8 with esters 3(4) in refluxing xylol or with hydrazid acid 6(7) by melting reagents afforded 7(5)-〚benzimidazol-2-yl〛methyl-5(7)methyl-1,2,4-triazolo〚1,5-a〛(〚4,3-a〛)pyrimidines 9(10). The structures of the annealed compounds have been elucidated by their ¹H, ¹³C NMR and Mass Spectroscopy data.     

Synthesis and stereochemical study of a trioxaquine prepared from cis-bicyclo〚3.3.0〛octane-3,7-dione

The preparation of a modular antimalarial drug named trioxaquine containing a cis-bicyclo〚3.3.0〛octane-3,7-dione is reported. Two diastereomeric racemates have been separated and characterised by NMR.     

Differentiation of planar chiral enantiomers of 〚Cp*M(2-alkyl-Phenoxo)〛 〚BF4〛 {M = Rh,Ir} by the trisphat anion

Precursor oxo-dienyl rhodium and iridium complexes 〚(η⁵-Cp*)M(η⁵-2-alkyl-oxodienyl)〛 〚BF₄〛 (2a–c) were prepared according to literature procedure. Addition of 〚n-Bu₄N〛 〚Δ-trisphat〛 (6) to a CD₂Cl₂ solution of these chiral derivatives has led to the NMR differentiation of the enantiomers. These results pave the way towards the preparation of enantiomerically pure o-quinone methide complexes.     

Complex examples of the Dowd–Beckwith rearrangement: a free radical route to 2-oxabicyclo 〚3.3.0〛octan-3,6-diones

The synthesis of 8-iodooxabicyclo〚3.2.1〛octanes from substituted benzoic acids via a reductive alkylation–halolactonization sequence is described. These iodolactones were converted to 2-oxabicyclo〚3.3.0〛octane derivatives upon treatment with either allyltri-n-butylstannane or tri-n-butylstannane via a process that involves a Dowd–Beckwith rearrangement. The scope and limitations of this process are discussed.     

Solution structure of the sheep prion PrP〚142-166〛: a possible site for the conformational conversion of prion protein

In order to get deeper insight into the molecular forces responsible for prion pathogenic conversion, conformational properties of a synthetic linear peptide derived from the globular core of sheep prion protein were studied by circular dichroism (CD) and nuclear magnetic resonance (NMR) spectroscopies. The studied peptide encompassing the 〚142–166〛 (in human numbering) region of sheep prion protein, folds in physiological conditions into a β-hairpin like tertiary structure, whereas, in the non-pathogenic form of protein and in trifuoroethanol (TFE), the region is engaged in largely α-helical conformation. Such structural duality of the fragment indicates a possible transconformational site within prion protein and may explain one of the early structural causes of prion diseases.     

Synthesis and X-ray crystal structure of 〚VCl3((–)-sparteine)〛 and 〚FeCl2((–)-sparteine)〛

Novel complexes of vanadium(III), chromium(III) and iron(II) containing the alkaloid (–)-sparteine as a bidentate ligand have been prepared. Two of them, 〚VCl₃((–)-sparteine)〛 and 〚FeCl₂((–)-sparteine)〛, were characterised by X-ray diffraction. Known cobalt(III) and nickel(II) analogue complexes were prepared using the same procedure.     

Synthèse et réactivité des dérivés de la 2,3-dihydro-3-hydroxy-2-phényl-1,5-benzothiazépin-4(5H)-one

New 1,5-benzothiazepinone derivatives have been synthesized. The cycloaddition of benzylazide with 5-propargyl-1,5-benzothiazepinone 7 gave compounds 9 and 10. The 1,5-benzothiazepinone 8 reacts with hydrazine to give 1,5-benzothiazepinone 11, which gave in hot acetic acid compound 12. The reaction of 3-chloro-1,5-benzothiazepinones 13, 14 or 15 with nucleophiles in DMF afforded the 2-benzylidenebenzothiazin-3-ones 16 and 17. The tosylate 18 gave the 1,5-benzothiazepinone 19 by reaction with N₃TMS in the presence of CsF in DMF.     

Dédoublement et détermination des excès énantiomériques des complexes de ruthéniumII hexacoordinés 〚Ru(bpy)2ppy〛+ et 〚Ru(bpy)2Quo〛+ (bpy = bipyridine,ppy = phénylpyridine,Quo = 8-quinolate) utilisés comme templates dans la construction de réseaux anioniques tridimensionnels

The bimetallic networks coordinated with oxalate bridges {〚M^IIM^III(C₂O₄)₃〛^–C⁺〛}_n form an important family of molecular magnets. The role of the cation C⁺ is fundamental for the nature of the obtained network (bi- or tridimensional). Thus, tridimensional polymers can be obtained in optically active forms using monocationic resolved templates such as 〚Ru(bpy)₂ppy〛⁺ 1 and 〚Ru(bpy)₂Quo〛⁺ 2. These cations were synthesized and resolved. A ¹H NMR technique based on the formation of diastereomeric salts obtained with optically active anion 〚ΔTrisphat〛^– {Trisphat = tris(tetrachlorobenzenediolato)phosphate(V)} was used to measure the enantiomeric excesses. To cite this article: M. Brissard et al., C. R. Chimie 5 (2002) 53–58     

Synthèse et étude structurale d’un nouvel hétéropolytungstate substitué Na8〚H3XIIIMIIW17O59(H2O)〛·36 H2O (X = SbIII,BiIII et M = Mn2+, Co2+, Ni2+, Cu2+, Zn2+) de structure identique à celle de 〚H2XIIIW18O60〛7– (X = As,Bi)

By mixing an aqueous solution of antimonotungstate at pH = 4–5 and an aqueous solution of manganese(II) chloride, of cobalt(II) chloride, of nickel(II) chloride, or of zinc, a monosubstituted heteropolytungstate 〚H₃Sb^IIIM^IIW₁₇O₅₉(H₂O)〛^8– is obtained (M^II = Mn^II, Co^II, Ni^II, Zn^II). The crystallographic study, associated to EPR, XANES, EXAFS, and proton NMR spectrometries, leads to a structure identical to this of 〚H₂As^IIIW₁₈O₆₀〛^7–. There are two moieties Sb^IIIW₉O₃₀ and H₃M^IIW₈O₃₀. It is concluded that the M^II atom substitutes a tungsten atom of the belt of six octahedra perpendicular to the ternary axis of the polytungstate. The same type of compound was obtained starting from bismuth chloride and copper acetate, that is 〚H₃Bi^IIICu^IIW₁₇O₅₉(H₂O)〛^8–.     

Chiral enrichment of 2-amino-2′-hydroxy-1,1′-binaphthyl

A new synthetic procedure for the formation of 2-amino-2′-hydroxy-1,1′-binaphthyl, and a new purification procedure through the formation of Schiff bases, purification of the Schiff bases, and breakdown of the Schiff bases through amine exchange, are described. Through the new purification procedure, greater than 99% purity of the compound can be obtained easily and reliably. A set of procedures were examined to compare the efficiency and reliability to resolve 2-amino-2′-hydroxy-1,1′-binaphthyl into enantiomers. A new procedure was discovered to enrich enantiomeric excess from less than 10% to 95–99% in one step. Even a racemic mixture from an achiral procedure can be enriched to 67% e.e. in about 4% yield. The X-ray crystal structure of the racemic mixture [rhombohedral, space group Iba2, a=15.718(2) Å, b=21.703(2) Å, c=8.5398(9) Å, V=2913.2(5) ų, R1=0.0705, Z=8, d_calcd=1.301 g/cm³, F(000)=1200 e] was solved to elucidate the intriguing behavior of this compound.     

Crystal Structure of 2-（2-Carboxy-4-hydroxy-6- methoxyphenoxy）-3,5-dichloro-6-hydroxy- 4-methylbenzoic Acid 1-Methyl Ester

The title compound, neogeodin hydrate （C17H14C1208, CAS： 94540-50-8）, was derived from marine fungus Aspergilhts terreus CRIM301. It was unequivocally characterized by IR, NMR spectroscopies, and single-crystal X-ray crystallography and tested for various biological activities. Neogeodin hydrate crystallizes in the triclinic space group P1 with a = 8.1159（5） A, b = 8.2472（4） A, c= 14.1278（7） A, a = 81.448（2）°, β = 84.860（2）°, γ= 70.400（2）°, V = 880.13（8） A3; Z = 2. It comprises a diphenyl ether, asterric acid skeleton and dichloro substituents. The methoxyphenoxy rings of the inversely related molecules form a ribbon-like structure that is stabilized by O-H...O hydrogen bonds through the doubly disordered carboxyl groups and by C-H...O interactions, generating the same R22（8） ring motif. The chlorinated methylbenzoate rings, making mostly a right angle, link the parallel upper and lower ribbons via bifurcated O-H...O and C-H...O hydrogen bonds, yielding endless channels. The channels formed are further sustained by C-H...O and π...π interactions Neogeodin hydrate exhibits inhibition against superoxide anion radical formation in the xanthine/xanthine oxidase （XXO） assay, but has no aromatase inhibitory activity.     

Crystal Structure of Bis(3-hydroxy-2-pyridyl)disulfide

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Synthesis of 2-hydroxy-5,6-diarylnicotinonitriles and 2-chloro-5,6-diarylnicotinonitriles from β-chloroenones

Vilsmeier–Haack reaction of β-ketoaldehydes leads to the formation of β-chloroenones and these chloroenones on treatment with malononitrile afford 2-hydroxy-5,6-diarylnicotinonitriles. But a one-pot reaction of β-ketoaldehydes with Vilsmeier–Haack reagent and malononitrile or cyanoacetamide results in the formation of 2-chloro-5,6-diarylnicotinonitriles in good yields.     

Etude des premières bandes d'absorption S0→S1 et S0→S2 du 5-méthoxyindole

The experimental and theoretical results obtained for 5-methoxyindole (5MOI) indicate a large energetic difference between the S₀ → S₁ and S₀ → S₂ transitions indicating a charge distribution very different from that of indole. A weak shoulder on the long wavelength side of the S₀ → S₁ band is attributed to a nπ* transition associated with the methoxy substituent. This feature has previously been attributed to a hot band. The effect of solvent on the molecule and the results obtained by the quantitative quantum CNDO/2 and CNDO/M methods are discussed.     

Synthesis of 3-chloro-N′-(2-hydroxy-6-pentadecylbenzylidene)benzothiophene-2-carbohydrazide

3-Chloro-N′-(2-hydroxy-6-pentadecylbenzylidene)benzothiophene-2-carbohydrazide has been synthesized by the reaction of 2-hydroxy-6-pentadecylbenzaldehyde with 3-chloro-1-benzothiophene-2-carboxylicacidhydrazide in the presence of glacial acetic acid in ethanol. The structure of this new compound was confirmed by elemental analysis, IR, ¹H NMR, ¹³C NMR and mass spectral analysis.