RESUMO
An efficient copper-catalyzed method for the synthesis of tetrazolo[5,1-a]isoquinolines has been developed starting from alkenyl-1,2-bis(boronates). The domino reaction underwent a Suzuki-Miyaura cross-coupling reaction and an azidation followed by an in situ [3 + 2] cycloaddition. Regioselective synthesis has been demonstrated by inverting the Suzuki-Miyaura cross-coupling reaction and the azidation.
RESUMO
Two BODIPYs and two boron ß-diketonates were threaded through a macrocycle bearing a 2,2'-biphenol unit, showing thus the ability of boron to act as a gathering atom. The new threaded species were characterized by 1D and 2D NMR spectroscopy as well as by X-ray crystallography for one of them and their properties rationalized with quantum chemistry to unravel the vibronic contributions. The BODIPYs exhibited interesting fluorescence features with quantum yields up to 91 % and enhanced photostability compared to their non-threaded homologues. A rotaxane was synthesized using this threading strategy after stoppering and removing the boron with potassium hydroxide.
RESUMO
A facile double oxidative annulation of (en-3-yn-1-yl)phenylbenzamides was developed allowing us to synthetize fused tetracyclic compounds. Under copper catalysis, the reaction proceeds with high efficiency and leads to new indolo[1,2-a]quinolines via a decarbonylative double oxidative annulation. On the other hand, under ruthenium catalysis, new isoquinolin-1[2H]-ones were obtained via a double oxidative annulation.
RESUMO
An efficient stereo-controlled synthesis of enyne and enediyne derivatives, via sequential Suzuki-Miyaura coupling reactions from easily prepared 1-alkene-1,2-diboronic esters and alkynyl bromides, is reported. The resulting enyne boronic esters were subjected to Borono-Mannich and Suzuki coupling reactions independently to obtain α,ß-unsaturated aminoester and tri-substituted olefin derivatives, respectively. Additionally, divergent syntheses of triazole and cyclopropylboronate derivatives are also reported.
RESUMO
2-Amino[2.2]paracyclophane reacts with salicylaldehyde or 2-hydroxyacetophenone to yield imines that then give access to a new series of boranils (8b-d) upon complexation with BF2 . These novel boron-containing compounds display both planar and axial chiralities and were examined experimentally and computationally. In particular, their photophysical and chiroptical properties were studied and compared to newly prepared, simpler boranils (9a-d) exhibiting axial chirality only. Less sophisticated chiral architectures were shown to demonstrate overall stronger circularly polarized luminescence (CPL) activity.
RESUMO
During the investigation of the water-sensitivity of (arylboronate alkylglucoside)-based organogels, we evaluated a series of twelve potential organogelators. They were synthesised in a single step from the corresponding arylboronic acids and alkylglucosides. Eight of them showed organogelation abilities in three solvents (toluene, cyclohexane, and ethyl myristate). Conformational minimisations of the potential organogelators permitted a clear relationship between the arylboronate orientation and the gelation effectiveness to be established. These gels were characterised by rheometry and SEM which revealed a gel-state originating from the self-assembly of the organogelators into long entangled fibres. SAXS confirmed the mode of packing in a hexagonal phase. Gels in toluene were found to be water-sensitive both after addition of a small amount of water and immersion into water. This study demonstrated that the main parameter impacting the water-sensitivity was the length of the alkyl chain at the anomeric position of the glucoside unit, much more than the functionalisation of an arylboronate moiety.
RESUMO
A Simmons-Smith stereodefined procedure for the synthesis of cyclopropyl-1,2-bis(boronates) has been developed starting from the corresponding alkenes. The resulting compounds were then subjected to regioselective Suzuki-Miyaura couplings to produce diversely tri- or tetra-substituted arylcyclopropanes in good yields. Further functionalization with 2-lithiothiophene provided 1,2-bis(aryl)cyclopropanes.
RESUMO
Mono- and di-boranil-substituted helicenes were prepared by BF2 -borylation of the corresponding anils, readily synthesized by condensation of 2-amino- and 2,15-diamino-helicenes with 4-(diethylamino)salicylaldehyde. After enantiomeric resolution using HPLC, their chiroptical properties including circularly polarized fluorescence in solution and in PMMA films were investigated and rationalized with the help of NMR, X-ray and quantum-chemical calculations.
RESUMO
The reaction of several alkylglucosides with phenyl boronic acid permitted easy access to a series of alkylglucoside phenyl boronate derivatives. This type of compound has structures similar to those of known benzylidene glucoside organogelators except for the presence of a boronate function in place of the acetal one. Low to very low concentrations of these amphiphilic molecules produced gelation of several organic solvents. The rheological properties of the corresponding soft materials characterized them as elastic solids. They were further characterized by SEM to obtain more information on their morphologies and by SAXS to determine the type of self-assembly involved within the gels. The sensitivity of the boronate function towards hydrolysis was also investigated. We demonstrated that a small amount of water (5 % v/v) was sufficient to disrupt the organogels leading to the original alkylglucoside and phenyl boronic acid; an important difference with the stable benzylidene-based organogelators. Such water-sensitive boronated organogelators could be suitable substances for the preparation of smart soft material for topical drug delivery.
RESUMO
Complimentary to classical hydroboration and boron-Wittig reactions, a new, efficient access to cyclic 1,3-dienyl boronic esters has been developed via diene or triene metathesis. Subsequently, fused pyrroles were synthesized with a broad substrate scope from the reaction of cyclic 1,3-dienyl boronic esters with arylnitroso compounds using a one-pot hetero-Diels-Alder/ring contraction sequence.
RESUMO
A stereoselective and convenient route has been demonstrated to access (Z)-1,2-diazido alkenes from the corresponding 1,2-diboronic esters via a copper-mediated reaction with sodium azide. Alternately, mono-functionalization was regioselectively carried out with trimethylsilyl azide as an azidation reactant. The in situ conversion of bis-azides to the corresponding bis-triazoles can be readily achieved in the presence of copper sulfate and sodium ascorbate, while the modification of the catalytic system opened a new convenient route to bis-triazolo-pyrazines, a new class of fused heterocycles.
RESUMO
4-Methylenechromanes were prepared via a three-step process from 2-borylated α-methylstyrenes. This sequence is based on a key glyoxylate-ene reaction catalyzed by scandium(iii) triflate. The resulting γ-hydroxy boronates, which cyclise to seven-membered homologues of benzoxaborole on silica gel, were cleanly oxidized with sodium perborate, and then cyclised under Mitsunobu conditions. Additionally, several further functional transformations of 4-methylenechromanes or their precursors were carried out to illustrate the synthetic potential of these intermediates.
RESUMO
An efficient and straightforward synthesis of isoquinolines is reported from internal alkenyl boronic esters, easily prepared from the corresponding 1,2-bis(boronates), via a sequential copper-catalyzed azidation/aza-Wittig condensation. This synthetic method has been used to synthesize quinisocaine, a topical anesthetic used for the treatment of pain and pruritus, and further extended to thieno[2,3-c]pyridines by using 2-thiophenecarboxaldehyde as coupling partner in the first step.
RESUMO
Enantiopure carbo[6]helicenyl boronates were synthesized using a photocyclization reaction as the key step. These compounds were further converted to various amino derivatives using copper-catalyzed azidation or amination and reductive alkylation of benzylazide by a helicenyl dichloroborane. Asymmetric Petasis condensation with glyoxylic acid and morpholine controlled by the helical chirality afforded the corresponding amino esters.
RESUMO
An efficient and straightforward synthesis of 1-amino-1H-indenes is reported from 1,2-bis(boronates) via a sequential Suzuki-Miyaura coupling/Petasis cyclization reaction. Starting from the same monoboronic ester intermediates, an intermolecular version of this approach also afforded (Z)-α,ß-unsaturated amino esters in moderate to good yields.
RESUMO
The simple octyl ß-D-galactofuranoside was previously described as a good bacteriostatic agent against Mycobacterium smegmatis, a non-pathogenic model of M. tuberculosis. In order to decipher its mechanism of action, STD NMR on whole M. smegmatis cells was implemented. It outlined the crucial role of the alkyl chain and the possibility of modulation on the furanosyl entity. Then, 16 new alkyl furanosides were synthesized in order to optimize the mycobacteriostatic activity. They all present the pending alkyl chain in a 1,2-trans configuration relative to the sugar ring. Three families were studied that differ by a substituent on the primary position of the galactofuranose ring, the series or the pending alkyl chain. Four of these neofuranosides showed growth inhibition inferior to the parent octyl ß-D-galactofuranoside. Double alkyl chains at C-1 and a polar substituent on the primary position of the furanoside significantly favored the activity. Finally, a mixed biantennary alkyl/aryl ß-D-galactofuranoside exhibited the best growth inhibition concentration at 90 µM.
Assuntos
Antibacterianos/farmacologia , Galactosídeos/farmacologia , Mycobacterium smegmatis/efeitos dos fármacos , Antibacterianos/química , Relação Dose-Resposta a Droga , Galactosídeos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium smegmatis/crescimento & desenvolvimento , Estereoisomerismo , Relação Estrutura-AtividadeRESUMO
The Borono-Mannich reaction of (Z)-1-alkene-1,2-diboronic esters proceeded regioselectively at the terminal C-B bond to afford (E)-γ-boronated unsaturated amino esters in good yields. These compounds were then subjected to Suzuki couplings for the creation of diversely substituted olefinic amino acid systems. Several other functional transformations were also carried out to illustrate the synthetic utility of the Petasis products.
RESUMO
We report on the synthesis of two new threaded BODIPYs 5 and 6 in good yields using boron as a gathering atom and a macrocycle with a 2,2'-biphenol unit. In addition to usual techniques, they were characterized by X-ray crystallography. Their electrochemical and optical properties were investigated. In particular, both compounds are highly emissive with photoluminescence quantum yields of 54 and 81 % respectively. In addition, they both show a high photostability.
RESUMO
A series of neamine derivatives were prepared from the cyclic carbonate and sulfate of 1,3,2',6'-tetraazido-3',4',-di-O-acetylneamine. Ring opening reactions with diversely substituted amines result in the formation of the corresponding carbamates or sulfonic acids with good overall yields. The antibacterial activities of the synthesized products against E. coli (DH5α) and S. aureus (RN4220) were evaluated. With isolated single regioisomers, the preponderant effect of the 5-positions of the carbamate substituent on the neamine core was demonstrated.
Assuntos
Antibacterianos/síntese química , Framicetina/química , Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Framicetina/farmacologia , Viabilidade Microbiana/efeitos dos fármacos , Estrutura Molecular , Staphylococcus aureus/efeitos dos fármacos , Relação Estrutura-AtividadeRESUMO
Hepatitis C virus (HCV) translation initiation is mediated by a highly structured and conserved RNA, termed the Internal Ribosome Entry Site (IRES), located at the 5'-end of its single stranded RNA genome. It is a key target for the development of new antiviral compounds. Here we made use of the recently developed HCV cell culture system to test the antiviral activity of artificial ribonucleases consisting of imidazole(s) linked to antisense oligodeoxynucleotides targeting the HCV IRES. Results from the cell culture model indicate that the naked antisense oligodeoxynucleotide displayed an efficient antiviral activity. Despite the increased activity observed with the addition of imidazole moieties when tested with the cell-free system, it appears that these improvements were not reproduced in the cellular model.