Etude des conditions d'accés aux 6H-, 7H- et 11H-pyrimidino-[4,5-a], [4,5-b], [5,4-a] [5,4-b] et [5,4-c]carbazoles. 1

The synthesis of dihydropyrimidinocarbazoles 12,15 and 18 was achieved by cyclization of tetrahydrocarbazolones with triformamidomethane. The oxidation with potassium permanaganate of dihydropyrimidinocarbazoles gave the pyrimidinocarbazoles 13,16 and 19. The application of the Sandemeyer reaction to amiononitrocarbazoles gave cyanonitrocarbazoles which could be reduced to aminocyanocarbazoles 1 and 7. Intramolecular cyclization of the carbazoles 1 and 7 afforded 3,4-dilhydro-4-oxo-6H-pyrimidino[5,4-b]carbazole 2 and 1,2-dighydro-1-oxo-6H-pyrimidino[5,4-b]carbazole 10 was obtained by cyclization of quinazolinyl hydrazone 9 with hydrochloric acid and acetic acid. The structure of the derivatives was determined by ¹H-nmr and the Overhauser effect.     

Synthèse et étude physicochimique des 1,2,4-triazolo[4,3-a]-pyridines et des 1,2,4-triazolo[2,3-a]pyridines

The synthesis of 1,2,4-triazolo[4,3-a] and [2,3-a]pyridines 7, 8 was achieved by cyclization of 2-hydrazino-8-nitropyridine 3a with formic acid. The 4,5,6,7-tetrahydro-1,2,4-triazolo[2,3-a]pyridine 13 and 8-amino-1,2,4-triazolo[2,3-a]pyridine 9 were obtained by catalytic hydrogenation. The reduction of triazolo pyridine 8 using stannous chloride led to the intermediate compound 10 which with acetic anhydride afforded 8-acetylamino-5-chloro-1,2,4-triazolo[2,3-a]pyridine 10a . The structure of the derivatives was determined by ¹H-nmr (DMSO-d₆).     

Pyrrolo[1,2-d]triazines-1,2,4 III. Etude de la dioxo-1,4 tetrahydro-1,2,3,4 pyrrolo[1,2-d]triazine-1,2,4

1,4-Dioxo-1,2,3,4-tetrahydro-l,2,4-pyrrolo[l,2-～-1,2,4-triazine (1) was synthesized either by cyclising the N-carbethoxyhydrazide of pyrrole-2-carboxylic acid (2) or by alkaline rearrangement of 2-(2-pyrrolyl>5-oxadi- azolone (3). The methylation reactions of the dilactam 1 were achieved with dimethyl sulfate or diazomethane and afforded mixtures of U-methylated and N-methylated derivatives which were isolated by gas chromatography and the structures of which were assigned using ir and ¹H nmr spectra.     

Pyrrolo[1,2-d]triazines-1,2,4. II. Etude des pyrrolo[1,2-d]triazinones-1 et -4

The synthesis of 1,2-dihydro-1-oxopyrrolo[1,2-d]-1,2,4-triazines was achieved by rearrangement of 2-pyrrolyloxadiazoles under alkaline conditions or by cyclisation of pyrrole N-ethoxymethylidene hydrazides. The cyclisation of the N-carbethoxy hydrazone of the pyrrole-2-carboxaldehyde gave the 3,4-dihydro-4-oxopyrrolo[1,2-d]-1,2,4-triazine. Electrophilic substitution reactions of the 1- and 4-pyrrolotriazinones were made either on the lactam nitrogen with methyl sulphate, benzyl chloride and monochloroacetic acid or on the pyrrole ring with bromine and nitric acid. The structure of the derivatives was determined by ¹H nmr.     

Analysis of chemically synthesized oleoylethanolamide by gas-liquid chromatography

Oleoylethanolamide (OEA) is known to potentially have beneficial biological effects on weight management by controlling food intake and activating lipid catabolism. In biological fluids, OEA and other endogenously biosynthesized fatty acid ethanolamides are usually analyzed by liquid chromatography-mass spectrometry (LC-MS). The present study provides analytical method to routinely assess the quality of OEA prepared for biological studies by gas-liquid chromatography (GLC). The preparation of OEA for biomedical studies can be performed by N-acylation of oleic acid/esters or using oleoyl chloride. In the present study, OEA was prepared by transamidation of triolein. The analysis of the synthesized OEA has been performed by gas-liquid chromatography of its trimethylsilyl ether (TMS) derivatives. Free OEA cannot be analyzed as such because dehydration of the ethanolamide moiety promptly happens in the GLC injection. This thermal degradation reaction gives rise to the formation of an oxazoline derivative. The TMS moiety prevents the reaction, and the structure of the formed derivative was assessed by mass spectrometry. We show here that OEA prepared for biological studies can be routinely analyzed by GLC after TMS derivative preparation.     

Reaction of aldimine anions with vinamidinium chloride: three-component access to 3-alkylpyridines and 3-alkylpyridinium salts and access to 2-alkyl glutaconaldehyde derivatives

N-tert-Butylimino derivatives of aldehydes were deprotonated with LDA and reacted with vinamidinium chloride to give 2-alkylaminopentadienimine derivatives, which were isolated as their corresponding hydrochloride in 68-81% yield. Reaction of these derivatives with ammonium acetate or salts of primary amines, in n-butanol at 80 degrees C, afforded the corresponding 3-alkylpyridines or 3-alkylpyridinium salts in high yield. Alkaline hydrolysis of 2-alkylaminopentadieneimine derivatives allowed a practical accesss to potassium salts of 2-alkylglutaconaldehyde.     

Electroactive nanorods and nanorings designed by supramolecular association of pi-conjugated oligomers

In investigations into the design and isolation of semiconducting nano-objects, the synthesis of a new bisureido pi-conjugated organogelator has been achieved. This oligo(phenylenethienylene) derivative was found to be capable of forming one-dimensional supramolecular assemblies, leading to the gelation of several solvents. Its self-assembling properties have been studied with different techniques (AFM, EFM, etc.). Nano-objects have successfully been fabricated from the pristine organogel under appropriate dilution conditions. In particular, nanorods and nanorings composed of the electroactive organogelator have been isolated and characterized. With additional support from an electrochemical study of the organogelator in solution, it has been demonstrated by the EFM technique that such nano-objects were capable of exhibiting charge transport properties, a requirement in the fabrication of nanoscale optoelectronic devices. It was observed that positive charges can be injected and delocalized all along an individual nano-object (nanorod and nanoring) over micrometers and, remarkably, that no charge was stored in the center of the nanoring. It was also observed that topographic constructions in the nanostructures prevent transport and delocalization. The same experiments were performed with a negative bias (i.e., electron injection), but no charge delocalization was observed. These results could be correlated with the nature of 1, which is a good electron-donor, so it can easily be oxidized, but can be reduced only with difficulty.     

Pozzolanic reactivity of silico-aluminous fly ash

For some years it has been possible to control the particle size of fly ashes, by-products of thermal power stations. Incorporating these very fine particles (obtained by grinding and/or pneumatic selection) improves the physical-mechanical characteristics of mortars and concretes. In this study, we measured the lime consumption of the various fractions (granulometric and densimetric) and identified by X-ray diffraction the neoformed phases by the pozzolanic reaction, to show that it is not sufficient to simply define the pozzolanicity of products based on lime consumption since it does not take into account the nature of the phases formed. The size of the particles used in the test samples also has a determining effect on the quantity of lime consumed. Before comparing results, it is necessary to ensure that the size of the particles (of the global ash and its constituents) be the same. Two distinct neoformed phases appear: CSH in the largest granular fractions (d>40 μm) and C<3AH6 in the smaller fractions.     

Cyclic(Alkyl)(Amino)Carbene (CAAC)-Supported Zn Alkyls: Synthesis,Structure and Reactivity in Hydrosilylation Catalysis

The reactivity of Zn^II dialkyl species ZnMe₂ with a cyclic(alkyl)(amino)carbene, 1-[2,6-bis(1-methylethyl)phenyl]-3,3,5,5-tetramethyl-2-pyrrolidinylidene (CAAC, 1 ), was studied and extended to the preparation of robust CAAC-supported Zn^II Lewis acidic organocations. CAAC adduct of ZnMe₂ ( 2 ), formed from a 1:1 mixture of 1 and ZnMe₂, is unstable at room temperature and readily undergoes a CAAC carbene insertion into the Zn−Me bond to produce the ZnX₂-type species (CAAC-Me)ZnMe ( 3 ), a reactivity further supported by DFT calculations. Despite its limited stability, adduct 2 was cleanly ionized to robust two-coordinate (CAAC)ZnMe⁺ cation ( 5⁺ ) and derived into (CAAC)ZnC₆F₅⁺ ( 7⁺ ), both isolated as B(C₆F₅)₄⁻ salts, showing the ability of CAAC for the stabilization of reactive [ZnMe]⁺ and [ZnC₆F₅]⁺ moieties. Due to the lability of the CAAC−ZnMe₂ bond, the formation of bis(CAAC) adduct (CAAC)₂ZnMe⁺ cation ( 6⁺ ) was also observed and the corresponding salt [ 6 ][B(C₆F₅)₄] was structurally characterized. As estimated from experimental and calculations data, cations 5⁺ and 7⁺ are highly Lewis acidic species and the stronger Lewis acid 7⁺ effectively mediates alkene, alkyne and CO₂ hydrosilylation catalysis. All supporting data hints at Lewis acid type activation–functionalization processes. Despite a lower energy LUMO in 5⁺ and 7⁺ , their observed reactivity is comparable to those of N-heterocyclic carbene (NHC) analogues, in line with charge-controlled reactions for carbene-stabilized Zn^II organocations.