Dérivés de désoxy-hydroxylamino-sucres et radicaux libres diglycosylnitroxydes correspondants. Communication préliminaire

Deoxy-hydroxylamino-sugar Derivatives and Corresponding Diglycosylnitroxides Radicals A number of sugar aldonitrones, including C,N-diglycosylnitrones, and ketonitrones have been treated with Grignard reagents or cyanide anion leading to the corresponding deoxy-hydroxylamino-sugars. On oxidation (air, H₅IO₆ or PbO₂), these compounds gave the corresponding nitroxide radicals whose ESR. spectra are reported. Analogues of disaccharides, in which the interglycosidic O-bridge is replaced by a hydroxyimino group, have been obtained by reacting a partially blocked sugar bearing a free hemiacetal group either with a deoxy-hydroxylaminosugar or with hydroxylamine, followed by reaction with an aldehydosugar and a reducing agent (NaBH₄). These reactions represents the key synthetic steps for the oligosaccharide-type synthesis of deoxy-hydroxyimino-oligosaccharides. Their oxidation yielded the corresponding nitroxide radicals whose ESR. spectra gave information on the conformation about the ‘interglycosidic’ bridge. This type of compounds should constitute useful spin markers for biological studies.     

Nouveaux exemples de radicaux libres stables de dérivés hétérocycliques de sucres. Communication préliminaire

Some more examples of stable free radicals of carbohydrate heterocyclic derivatives 2-Glycosyl-4,4,5,5-tetramethylimidazoline- 3-oxide-1-oxyls and 2-glycosyl-4,4,5,5-tetramethylimidazoline 1-oxyls have been prepared in nine carbohydrate series, which proves the generality of the method. The hyperfine coupling constant between the free electron and the α-proton of the glycosyl group is never very large (0-2.3 G) but a correlation between its value and the structure of the aglycone has been noted. Free radicals of that type, stable in aqueous solutions, are potentially interesting for biological studies.     

Heterospin complexes of polynuclear Ni<Superscript>II</Superscript> compounds containing hexafluoroacetylacetonate and pivalate ligands with nitroxides

The heterospin mixed-ligand complex [Ni₆(OH)₄Piv₄(hfac)₄(NIT-Ph)₂] (1) (NIT-Ph is 4,4,5,5-tetramethyl-2-phenyl-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide, hfac is hexafluoroacetylacetonate, and Piv is pivalate) was synthesized. The method for the synthesis of complex 1 is based on the replacement of acetone molecules in the hexanuclear complex containing the hexafluoroacetylacetonate and pivalate ligands [Ni₆(OH)₄Piv₄(hfac)₄(Me₂CO)₄] by NIT-Ph molecules. Two monodentate NIT-Ph molecules replace four acetone molecules, because the coordination of the O atom of the nitroxide group results in the blocking of one of the positions in the coordination environment of Ni^II the access to which is hindered by the phenyl ring of NIT-Ph. As a result, these ions are in a square-pyramidal environment unusual of Ni^II. In the low-temperature range, the dependence of the magnetization of 1 on the magnetic field is described by the Brillouin function. The reaction of [Ni₆Piv₄(hfac)₄(OH)₄(Me₂CO)₄] with the nitronyl nitroxide radicals 4,4,5,5-tetramethyl-2-(4-pyridyl)-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide (NIT-p-Py) or 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihydro-1H-imidazol-1-oxyl 3-oxide (NIT-Iz) containing the pyridine or 1-methylimidazol-5-yl substituent, respectively, in the side chain is accompanied by the decomposition of the polynuclear fragment and affords the mononuclear complexes Ni(hfac)₂(NIT-p-Py)₂ and Ni(hfac)₂(NIT-Iz)₂, respectively. The reaction of 4,4,5,5-tetramethyl-2-(1-methyl-1H-imidazol-5-yl)-4,5-dihyd-ro-1H-imidazol-1-oxyl (Im-Iz), which is the imine analog of NIT-Iz, with [Ni₆Piv₄(hfac)₄(OH)₄(Me₂CO)₄] afforded the decanuclear complex [Ni₁₀(OH)₈Piv₄(hfac)₈(Im-Iz)₂(H₂O)₆]. The molecular and crystal structures of all heterospin compounds were determined, and the magnetic properties of all compounds were investigated in the 2–300 K temperature range.     

Key influence of the nature of the substituent in the propynal molecule on the outcome of its reaction with vicinal di(<Emphasis Type="Italic">N</Emphasis>-hydroxyamine)

The reaction of propynals X-C≡C-CHO, where X = Alk or Ar, with 2,3-di(N-hydroxyamino)-2,3-dimethylbutane gives exclusively 1-X-2-(1-hydroxy-4,4,5,5-tetramethylimidazolidin-2-ylidene)ethanones. In the case of X = Me₃Si, the reaction affords 2-(2-trimethylsilylethynyl)-4,4,5,5-tetramethylimidazolidine-1,3-diol. The reaction of propynal containing X = Et₃Ge yields both types of the products. The resulting imidazolidine-1,3-diol can be quantitatively isomerized to imidazolidin-2-ylideneethanone, oxidized to 2-[2-(triethylgermyl)ethynyl]-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, or transformed into ethynyl-substituted nitronyl nitroxide. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 588–594, March, 2008.     

XPS spectra of free nitroxyl radicals and their electronic structure

The N(1s) and O(1s) XPS spectra of stable nitroxyl radicals and molecules with a related heterocycle structure: 4,4,5,5-tetramethyl-2-phenyl-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, 4,4,5,5-tetramethyl-2-(3-nitrophenyl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, 4,4,5,5-tetramethyl-2-(2-hydroxyphenyl)-4,5-dihydro-1H-imidazole-3-oxide-1-oxyl, 4,4,5,5-tetramethyl-2-(2-hydroxy-3-nitrophenyl)-4,5-dihydro-1Himidazole-3-oxide-1-oxyl, and 4,4,5,5-tetramethyl-2-phenyl-4,5-dihydro-1H-imidazole-3-oxide were studied. The possibility to apply X-ray electron spectra for investigation of the charge electron and spin density distribution on free radical atoms and at their coordination by a metal is considered.     

S<Stack><Subscript>N</Subscript><Superscript>H</Superscript></Stack> Reaction of lithiated nitronyl nitroxide with quinoline <Emphasis Type="Italic">N</Emphasis>-oxide

The S_N^H reaction of lithiated 4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazole-1-oxyl 3-oxide with quinoline N-oxide affords 4,4,5,5-tetramethyl-2-(1-oxidoquinolin-2-yl)-4,5-dihydro-1H-imidazole-1-oxyl 3-oxide.     

Radicaux libres dérivés de sucres. V. Dérivés d'osamines N-hydroxylées et composés voisins Communication préliminaire

Free sugar radicals. V. Deoxyhydroxylaminosugar derivatives and related compounds We describe several synthetic routes to deoxyhydroxylaminosugar derivatives of the type Glyc-N(OH)-R where Glyc stands for a sugar moiety linked by any of its C-atoms except the anomeric one and R for one of the following substituants: H-atom, acyl, phosphoryl groups, aminoacid or sugar residues. Compounds of the above structure are potentially close analogs, homoisosteres, ? NOH? replacing ? O? , of biochemically important molecules. Under aerobic conditions, solutions of these derivatives contain minute concentrations of the corresponding nitroxide radicals which do not decrease significantly the resolution of the NMR. spectra but render these compounds usable as a new kind of spin labels. Spectroscopic properties (¹H-NMR., ¹³C-NMR., ESR.) of some of these compounds are reported.     

Crystal Structure and Magnetic Properties of Pyridyl-Substituted Nitronyl Nitroxides

X-ray crystal structure and cryomagnetic properties of three organic radicals, 2-(2-pyridyl)-4, 4,5,5-tetramethyl-4,5-dihydro-1-H-imidazol-1-oxyl-3-N-oxide(NIT-oPy) 1, 2-(3-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-l-H-imidazol-1-oxyl-3-N-oxide(NIT-mPy) 2 and 2-(6-methyl-2-pyridyl)-4,4,5,5-tetramethyl-4, 5-dihydro-1-H-imidazol-1-oxyl-3-N-oxide(NIT-6M-oPy) 3 were investigated. The crystal structures of compounds 1-3 show the same feature of a P2₁/c space group of a monoclinic system. Two crystallographically independent molecules were found in the crystals of compounds 1-3. The temperature dependence of magnetic susceptibility of compounds 1-3 revealed an intermolecular antiferromagnetic exchange interaction.     

Intermolecular Ferromagnetic and Antiferromagnetic Interactions in Halogen-Bridged Copper(I) Imino Nitroxides: Crystal Structures and Magnetic Properties of [Cu(I)(&mgr;-X)(imino nitroxide)](2) (X = I or Br)

Reaction of CuI or CuBr with some imino nitroxides in methanol gave the halogen bridged dinuclear Cu(I) complexes [Cu(&mgr;-I)(impy)](2) (1), [Cu(&mgr;-I)(immepy)](2) (2), [Cu(&mgr;-Br)(immepy)](2) (3), and [Cu(&mgr;-Br)(imph-NO(2))](2) (4), respectively (impy = 2-(2'-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl, immepy = 2-(6'-methyl-2'-pyridyl)-4,4,5,5-tetramethyl-4,5-dihydro-1H-imidazolyl-1-oxyl, imph-NO(2) = 2-(4'-nitrophenyl)-4,4,5,5-tetramethyl-4,6-dihydro-1H-imidazolyl-1-oxyl). Crystal structures and magnetic properties have been studied. Complexes 1-4 have dimeric structures where two copper ions are doubly bridged by halide ions in a &mgr;(2) fashion. In 1-3, each copper ion is tetrahedral with a bidentate imino nitroxide and two halide ions, and the two copper ions are separated by 2.592(2), 2.6869(8), and 2.7357(6) ?, respectively. In 4, triangular coordination sites of the copper ions are completed with a nitrogen atom from the imino nitroxide and two bromide ions bridging the two copper ions with a separation of 3.074(2) ?. Ligand imino nitroxides in 1-4 form one-dimensional radical chains, and the chains are linked with halocuprate dimer units. Structural and magnetic susceptibility data support that radicals in 1 and 4 are ferromagnetically stacked, while radicals in 2 and 3 form an antiferromagnetic chain. The magnetic behaviors are discussed in connection with the stacking modes of the radicals and bridging conformations. Crystal data (Mo Kalpha, lambda = 0.71069 ?): 1, orthorhombic, space group P2(1)2(1)2(1), a = 17.807(2) ?, b = 8.595(2) ?, c = 19.336(6) ?, and Z = 4; 2, monoclinic, space group P2(1)/c, a = 9.941(2) ?, b = 18.482(2) ?, c = 8.337(2) ?, beta = 96.41(2) degrees, and Z = 2; 3, monoclinic, space group P2(1)/c, a = 9.964(6) ?, b = 18.167(4) ?, c = 8.009(7) ?, beta = 95.81(6) degrees, and Z = 2; 4, monoclinic, space group P2(1)/c, a = 11.991(7) ?, b = 17.998(8) ?, c = 7.215(6) ?, beta = 104.07(6) degrees, and Z = 2.     

Magnetic interactions in supramolecular N-O...H-C[triple bond]C- type hydrogen-bonded nitronylnitroxide radical chains

Two paramagnetic building blocks, 2-(4-ethynyl-1-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl (3) and 2-(5-ethynyl-2-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl (4) were synthesized and crystallized. Single crystal X-ray studies of 3 and 4 show the formation of supramolecular head-to-tail one-dimensional H-bonded (N-O...H-C[triple bond]C- type) chain structures with O...C distances of 3.181 and 3.155 A, respectively. High-resolution isotropic liquid state (c相似文献   

Dérivés d'énose- et d'ynosephosphonates et composés voisins. Communication préliminaire

Derivatives of enose- and ynosephosphonates and related compounds. Preliminary communication The gem-dibromo terminal enoses 1 and 7 are convenient sources of glycosylacetylenes which upon reaction with phosphorus electrophiles gave the phosphorusbearing acetylenic sugars 4, 5 and 8 . Compounds 5 and 8 underwent cycloaddition reactions leading to isoxazolyl-C-glycosides 6 and 9 respectively. The nitroolefinic sugar derivative 11 gave upon bromination-dehydrobromination the first example of a new kind of potentially useful synthetic intermediates, the gem-bromonitroenose 12 . The enosephosphonate 13 was also prepared from 11 . The diglycosylhydroxylamine 18 represents another type of phosphorus-bearing acetylenic sugar derivative. Some ¹H- and ¹³C-NMR. data relative to the new types of phosphorus-containing sugar derivatives synthesized are given.     

Réactions de Friedel et Crafts de dérivés aromatiques sur les composés dioxo-1,4,2,3-non saturés. IV. Réactions des hydroxy-5-ouchloro-5-diméthyl-3,5- ou diméthyl-4,5-dihydro-2,5-furannones-2

Friedel-Crafts reactions of aromatic derivatives with 1,4-dicarbonyls 2,3-éthylenic compounds. Part IV. Reactions of 5-hydroxy or 5-chloro 3,5-dimethyl or 4,5-dimethyl 2 (5 H) furanones We studied the Friedel-Crafts reactions of 2-(5H)-furanones. In the presence of sulfuric acid and of an aromatic derivative, 5-hydroxy- or 5-chloro-5-methyl-2-(5H)-furanones with one methyl group either in the 3 position, or in the 4 position generally give the corresponding 5-aryl-2-(5H)-furanones, while with aluminium chloride, it is possible to obtain, when a reaction takes place, isomeric 1H-indenecarboxylic acids. However, in a particular case, an addition to the substrate's double bond is observed. The 3-aryl-5-hydroxy-tetrahydrofuran-2-one obtained is methylated in two ways and gives either a cyclic product, or a linear one. In two cases tautomerism between 1H-1-indenecarboxylic acid and 1H-3-indenecarboxylic has been shown by ¹H-NMR.     

Un nouvel exemple de transposition: l'épimérisation en C(3) d'hydroxy-3-δ1-pyrazolines dérivées de sucres

A Novel Example of Reversible Ring Opening: The Epimerization at C(3) of Sugar 3-Hydroxy-Δ¹-pyrazolines Reaction of 1 (either geometrical isomer) with hydrazine followed by in situ Ag₂O oxidation led to two pairs of interconverting isomers 4 ? 5 and 6 ? 7 . By the same treatment, (Z)- 10 and (or) (E)- 10 gave the pair 11 ? 12 . Acetylation of 4 ? 5 led to a non interconverting mixture of 8 and 9 . This fact, and the lack of incorporation of ¹⁸O when the epimerization took place in the presence of H₂¹⁸O indicated that the most probable mechanism consisted in a reversible ring opening ( D ? E ? F ). The kinetic parameters of these reactions are given and structural assignments proposed for the new compounds.     

Dérivés de sucres benzimidazoliques et benzothiazoliques

Benzimidazole and benzothiazole sugar derivatives Simple aldehydosugars such as 1 or 2 , by reaction with o-phenylenediamine, gave the corresponding benzimidazoles 3 and 4 . Whereas the unperturbed α, β-unsaturated aldehydosugar D gave the benzodiazepine E upon treatment with o-phenylenediamine, the formyl-bearing alkenyl acetals 5 and 8 led, in the same conditions, to the benzimidazoles 6 and 9 respectively or, on reaction with o-aminothiophenol, to the benzothiazoles 7 and 10 respectively. This difference in reactivity is explained by the electrondonor ability of the oxygen atom of the alkenyl acetal function as shown by the ¹³C-RMN. spectra.     

Magnetic interactions in a new heterospin complex involving nitroxide radical and oxamido-bridged copper(II)

A new binuclear copper(II) complex [Cu₂(oxpn)(IM2py)₂](ClO₄)₂, containing four spin carriers with pyridyl-substituted nitroxide radicals has been synthesized and characterized structurally and magnetically (oxpn?=?N,N′-bis(3-aminopropyl)oxamido, IM2py?=?2-(2′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl). The structure of the complex consists of centrosymmetric trans oxamido-bridged copper(II) binuclear units and nitroxide radicals. The coordination geometry around each copper atom is distorted square pyramidal and the apical position is occupied by a nitrogen atom of the imidazoline ring of a radical ligand. Magnetic analysis indicates that the complex exhibits strong antiferromagnetic coupling between copper(II) ions through the oxamido bridge and a ferromagnetic interaction between copper(II) ions and radical ligands. The magnetic behaviour is discussed with reference to the crystal structure.     

Structures and magnetic properties of two new heterospin complexes involving nitroxide radicals and oxamido-bridged copper(II)

Two new binuclear copper(II) complexes containing four spin carriers with pyridyl-substituted nitroxide radicals have been synthesized and characterized structurally and magnetically. These complexes are formulated as [Cu₂(oxap)(IM4py)₂](ClO₄)₂ (1) and [Cu₂(oxap)(NIT4py)₂](ClO₄)₂ (2), respectively, in which oxap stands for N,N′-bis(2-aminopropyl). IM4py stands for 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl and NIT4py for 2-(4′-pyridyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide. The structures of the complexes consist of centro-symmetric trans oxamido-bridged copper(II) binuclear units and nitroxide radicals. In 1 and 2 the copper atoms are in a distorted square plane and radicals (IM4py and NIT4py) coordinate to copper via nitrogen atoms from pyridine rings. Magnetic analysis indicates that 1 and 2 exhibit strong metal-metal antiferromagnetic coupling through oxamido-bridged and antiferromagnetic exchange interactions between copper(II) ion and radicals, respectively. The magnetic behaviors are discussed with reference to their crystal structures.     

Dérivés diglycosyliques. Communication préliminaire

Diglycosyl Derivatives. Preliminary communication Novel types of diglycosyl compounds, some of them bearing a resemblance to natural di- or tri-saccharides are described: a diglycosyldiyne ( 1 ), a diglycosylthiophene ( 2 ), a diglycosylaziridine ( 3 ), a diglycosyldioxolane ( 4 ), as well as six C,N-diglycosylnitrones, 9b–9f and 14 . These C,N-diglycosylnitrones, on treatment with an acetylenic Grignard reagent, led to the expected acetylenic diglycosyl-hydroxylamine 11 , whereas diglycosylisoxazolines (f. ex. 10 ) were obtained when these nitrones underwent 1,3-dipolar cycloaddition to acetylenic compounds.     

Carbocyclisations et hétérocyclisation de dérivés orthodibenzylés,par action du soufre

1,4-Diphenyl-2,3-dibenzylbutadiene is a good precursor of o-dibenzylated compounds by cycloaddition reactions. It gives a naphthacene derivative by a three step synthesis from ethyl oxalate. Sulfur treatment of new o-dibenzylated aromatic compounds gives benzo[c]thiophens, and also naphtho[2,3-c]thio-phens. Carbocyclization reactions appear with benzo[a]ace-anthrylene and dihydroindeno[2,l-a]fluorenc formation.     

Dérivés C-Glycosyliques XXXII. Synthèse de dérivés spiro-C-glycosylidéniques par cyclisation nucléophile. Communication préliminaire

C -Glycosylic derivatives XXXII. Synthesis of spiro-C -glycosylidenic derivatives via nucleophilic cyclization. On treatment with compounds bearing two nucleophilic groups as ethylenediamine, o-phenylenediamine or their monooxa or monothia analogues, 1,2:5, 6-di-O-isopropylidene-α-D -ribo-hexofuranos-3-ulose gave with excellent yields the corresponding spiro-C-glycosylidenic derivative; for example, when using o-phenylenediamine, a spirobenzimidazoline ( 5 ) was obtained. The latter compound underwent, on oxidation, a ring expansion to a morpholinobenzimidazole ( 8 ). Spirobenzodiazepines, spirobenzooxazepines and spirobenzothiazepines were formed when applying the same type of cyclization reaction to 3-C-acetylmethylene-3-deoxy-1,2:5,6-di-O-isopropylidene-α-D -ribo- and α-D -xylo-hexofuranoses.     

Cross-coupling of aryl iodides with paramagnetic terminal acetylenes derived from 4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxide

2-(Arylylethynylphenyl)-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxides 12 and 13 were synthesized by cross-coupling of aryl iodides with 1-alkynes containing the 4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxide fragment. A procedure was developed for the preparation of 3- and 4-ethynylbenzaldehydes with the use of 2-methylbut-3-yn-2-ol.