Photolyse d'oxaziridines. 10. Photolyse et thermolyse d'oxaziridines N-arylées

The nature of the nitrogen substituent does not effect the regio-se;ectivity of lactams derived from photolysis or thermolysis of sprioxaziridines. The thermolysis of N-arvlspriooxziridinies is a very good synthetic methos to obtain N-aryl heterocycles.     

Synthèse électrochimique du cycle époxydique. Communication préliminaire

The polarographic behaviour of ditosyloxy alkanes TsO(CH₂)_nOTs in aprotic medium suggests that intramolecular cyclisation takes place after reductive cleavage of a single SO₂? O bond at the dropping electrode. This hypothesis was verified by controlled potential electrolysis of the lower homologues at a mercury cathode. High yields of epoxy compounds are obtained by this method.     

Structure électronique de dérivés sulfurés : Partie V. spectres électroniques d''hétérocycles thio-carbonylés

The experimental and theoretical spectra of thiocarbonyl heterocyclic compounds with two heteroatoms in the position to the thiocarbonyl group have been studied.

The theoretical interpretation of the CNDO/S results including an extension to the third period, i.e. 3d orbitais, is in good agreement with the saturation effect as well as with the influence of the intracyclic heteroatoms on the typical absorptions of the thiocarbonyl group.     

L'isomérie géométrique d'amidines mono-substituées de l'acide benzothiazole-carboxylique-2. Isomères anti à carboxyle normal,isoméres syn à carboxyle énolisé

The condensation of methyl benzothiazole-2-iminicarboxylate with α-amino-acetic esters gives rise to amidines possessing only one (I) of the two possible tautomeric structures. Both syn and anti isomers have been characterized of the single tautomer. This is the first demonstration of geometrical isomerism around the imine group in amidines. The carboxylic esters and the free acids of the syn fro exist exclusively as the enol, whereas the anti derivatives prefer the carboxyl structure. The existence of these isomers has been confirmed by their IR., UV., and NMR. spectra as well as by the inversion of their configuration and the formation of cyclic derivatives.     

Synthèse d'azido dithiényl-1,2 éthènes et éthanes

Two convenient preparations of azido-1,2-dithienylethenes are described. The synthesis of azido-1,2-dithienylethanes proceeds via metalation (n-Buli) and subsequent treatment by tosylazide of bromo-1,2-dithienyl-ethanes. The structures of the obtained derivatives were established on the basis of ¹H nmr, ir, and mass spectral data.     

Hétérocycles à fonction quinone. 7. Benzo[f]quinazolinediones-7,10 à action antitumorale potentielle

Few benzo[f]quinazoline-7,10-diones 4a-c are prepared by oxidation, with potassium nitrosodisulfonate, of the corresponding benzo[f]quinazolinamines, made by reduction of the nitro analogues which were obtained from 8-methoxybenzo[f]quinazolin-1(2H)-one. The compound 4a shows an interesting cytotoxicity.     

Etude de la décomposition thermique d'azido dithiényl-1,2 éthènes et éthanes

Thermal decomposition of azido-1,2-dithienylethenes 1 gave thienyl 4H-thieno[3,2-b]pyrroles 3 . For the 3,4-disubstituted thiophene derivatives 2 , the same reaction led to the amino-1,2-dithienylethenes 4 . In contrast, only azido-1,2-dithienylethanes 7 led to thienyl-5,6-dihydro-4H-thieno[3,4-b]pyrroles 8 . The structure of the obtained derivatives was established on the basis of ¹H nmr, ir, and mass spectral data.     

Préparation de quelques 4-nitroisoxazoles à partir de pseudonitrosites de cétones éthyléniques du type chalcone

The Synthesis of some 4-Nitroisoxazoles from Pseudonitrosites of Chalcones The action of dinitrogen trioxide with α,β-unsaturated ketones of the chalcone type leads to pseudonitrosites (Table 1) which are cyclized to 4-nitro-3,5-diarylisoxazoles (Table 2).     

études sur les composés organométalliques,VIII. Synthése du tétrabenzyltitane

Tetrabenzyltitane is prepared by reaction of TiCl₄ on dibenzylmagnesium in pentane or hexane at – 20° in the presence of a small amount of ether.     

études sur les composés organométalliques IX. étude spectrophotométrique de quelques complexes du tétrachlorure de titane avec des di- et triamines tertiaires

The complexes of TiCl₄ with various tertiary di- and triamines are studied by using IR, spectroscopy. Assignments for the observed frequencies are proposed.     

Influence de la vitesse de chauflage sur l'atomisation électrothermique en spectrométrie d'absorption atomique. Applications aux éléments volatils, cadmium et plomb

The advantages of electrothermal atomization by rapid heating (faster than 2000°C s⁻¹) in atomic absorption for the determination of volatile elements are studied. The aim is to control the matrix effects, particularly the very high non-specific absorptions. It is shown that, unlike normal heating, now rapid heating makes it possible to atomize a volatile element without hardly covolatilizing its matrix, as a result of the change in the optimum atomization temperatures.Application examples are given: direct determination of cadmium and lead (atomized respectively at only 900 and 960°C) in sea water and related products. This method is likely to be applicable to other matrices which covolatilize normally with other elements. The mechanisms of atom formation in rapid heating are also investigated.     

Identification de stérols à chaînes latérales courtes dans l′éponge Damiriana hawaiiana

Identification of short side chain sterols in the sponge Damiriana hawaiiana The steroidal composition of the sponge Damiriana hawaiiana is examined. Twenty-seven components are identified. In addition to the C₂₆-C₂₉, Δ⁵-mono and diunsaturated sterols, the sponge contains sterols without side-chain: androsta-5, 16-dien-3β-ol( 1 ), androst-5-en-3β-ol( 2 ); sterols with a non-functionalized side-chain consisting of two, three, four, five and six carbon atoms: pregna-5, 20-dien-3β-ol( 5 ), pregn-5-en-3β-ol( 6 ), 23, 24-bisnor-chola-5, 20-dien-3β-ol( 7 ), 23, 24-bisnor-chol-5-en-3β-ol( 8 ), 24-nor-chol-5-en-3β-ol( 10 ), chol-5-en-3β-ol( 11 ), 26, 27-bisnor-cholest-5-en-3β-ol( 12 ), and sterols possessing a short oxygenated side-chain such as 3β-hydroxy-androst-5-en-17-one( 3 ), androst-5-en-3β, 17β-diol( 4 ) and 3β-hydroxy-26, 27-bisnor-22-trans-cholesta-5, 22-dien-24-one( 14 ). The probable biological or dietary origin rather than artifact production of these hitherto undescribed components from marine sources is supported by their relatively high concentration and their relative proportions, both very different from those expected for autoxidation.     

Identification de stérols à chaîne latérale oxygénée dans une éponge de l'espèce Hyrtios

Thirty-two sterols are identified in the sponge Hyrtios sp. In addition to fourteen monohydroxylated compounds, the sterol fraction contains eight functionalized sidechain sterols, three of them new: 3 β-hydroxy-24-norchol-5-en-23-al (19) , (22-trans)-3 β-hydroxycholest-5, 22-dien-24-one (20) and (22R, 23R, 24S) or (22S, 23S, 24S)- 22,23-epoxy-24-methylchoest-5-en-3 β-ol (24). The probable biological origin, rather than artifact production, of these undescribed components is discussed.     

Substitution électrophile aromatique dans l'anhydride sulfureux liquide. Etude cinétique de la réaction de bromation d'anisoles monosubstitués. Transmission des effets électroniques et caractéristiques de l'état de transition

Reactivity-structure correlations for anisole and eleven of its substituted derivatives established from bromination rate constants in liquid SO₂, unlike observations in water, show the reaction to be highly sensitive to substituent effects, (ρ = ?7.1; ρ = ?10.51). This result is ascribed to the solvation of the methoxy group which decreases the conjugation of para-substituted (ρ = ?9.70) compared to that of ortho-substituted derivatives (ρ = ?8.86). The highly solvated transition state lies far from reactants on the reaction coordinate and the positive charge developed in this state is nearly unity.     

Recherche d'analogues de nucléosides à activité antivirale

Search for Antiviral Nucleosides Analogues In contrast to the reported impossibility of obtaining the expected products when 1-(2,3-O-isopropylidene-1,5-dialdoribofurannos-1-yl)uracile ( 2 ) was treated with stabilized ylides, we prepared in good to excellent yields the modified nucleosides 4–9 by reaction of 2 respectively with acetylmethylidene-, benzoylmethylidene-, ethoxymethylidene-, methoxymethylidene-, succinimidylidene- or N-phenylsuccinimidylidene-triphenylphosphorane. Compounds 4–10 were tested against the herpes virus type 1 (HF) and influenza virus A₂/Scotland. The modified nucleoside 9 showed a limited but significative activity against the herpes virus.