α-Halogenoacetanilides as hydrogen-bonding organocatalysts that activate carbonyl bonds: fluorine versus chlorine and bromine.

α-Halogenoacetanilides (X=F, Cl, Br) were examined as H-bonding organocatalysts designed for the double activation of CO bonds through NH and CH donor groups. Depending on the halide substituents, the double H-bond involved a nonconventional CH⋅⋅⋅O interaction with either a HCXn (n=1-2, X=Cl, Br) or a HCAr bond (X=F), as shown in the solid-state crystal structures and by molecular modeling. In addition, the catalytic properties of α-halogenoacetanilides were evaluated in the ring-opening polymerization of lactide, in the presence of a tertiary amine as cocatalyst.

Efficient metal-free synthesis of various pyrido[2',1':2,3]imidazo- [4,5-b]quinolines.

Dancing with diversity: The synthesis of diverse pyrido[2',1':2,3]imidazo[4,5-b]quinolines bearing several substitution patterns was developed based on combining a multicomponent reaction (Groebke-Blackburn-Bienaymé reaction) with an original cyclization as a secondary transformation (see scheme; DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene).

Pharmaceutical development and optimization of azithromycin suppository for paediatric use.

Pharmaceutical development and manufacturing process optimization work was undertaken in order to propose a potential paediatric rectal formulation of azithromycin as an alternative to existing oral or injectable formulations. The target product profile was to be easy-to-use, cheap and stable in tropical conditions, with bioavailability comparable to oral forms, rapidly achieving and maintaining bactericidal concentrations. PEG solid solution suppositories were characterized in vitro using visual, HPLC, DSC, FTIR and XRD analyses.

Efficient synthesis and first regioselective C-3 direct arylation of imidazo[1,2-b]pyrazoles.

Highly regioselective: An efficient synthesis of the imidazo[1,2-b]pyrazole core has been developed, and the first regioselective palladium-catalyzed direct arylation of the C-3 position is described (see scheme). Good to excellent yields were obtained for a wide range of aryl partners with electron-rich and electron-poor substituents. This methodology allows rapid access to a large variety of imidazo[1,2-b]pyrazole products and could open the way to the design of new biologically active compounds.

Hemisynthesis and antiproliferative properties of mono-[O-(14-benzoylaconine-8-yl)]esters and bis-[O-(14-benzoylaconine-8-yl)]esters.

A series of mono- and bifunctional acyl compounds, build from the 8-O-azeloyl-14-benzoylaconine scaffold and differing by the length of the alkyl linker chain, were synthesised and evaluated against a panel of human tumour cell lines, A-549 (lung cancer), MCF-7 (breast cancer) and HCT-15 (colon cancer). None of the mono-[O-(14-benzoylaconine-8-yl)]esters displayed in vitro activity against tumour cells (IC(50) > 60 μM). However, three bis-[O-(14-benzoylaconine-8-yl)]esters presented a noticeable in vitro cytotoxic activity, those bearing 7, 8 and 9 carbon atoms between the two aconitine moieties, with IC(50)s ranging between 4 and 28 μM.

1-Allyl-3-phenyl-quinoxalin-2(1H)-one.

The title compound, C(17)H(14)N(2)O, crystallizes with two mol-ecules in the asymmetric unit. The dihedral angles between the mean planes of the quinoxaline ring system and the phenyl ring in the two mol-ecules are 38.27 (10) and 37.

2-(3H-1,3-Benzothia-zol-2-yl-idene)-propane-dial.

In the title compound, C(10)H(7)NO(2)S, the dihedral angle between the benzimidazole and malonaldehyde group is 1.41 (2)°. An intra-molecular hydrogen bond is formed between the NH group and one of the adjacent carbonyl O atoms.

Insights into the effects of functional groups on carbon nanotubes for the electrooxidation of methanol.

Functionalized carbon nanotubes were used as a support for PtCo nanoparticles. Their performance as electrocatalysts for the electrooxidation of methanol was evaluated by cyclic voltammetry and in situ FTIR reflectance spectroscopy. The onset potentials for both the electrooxidation of methanol and the production of CO(2) shifted to less positive values for catalysts prepared with more oxygen groups on the support.

New ferrocenic pyrrolo[1,2-a]quinoxaline derivatives: synthesis, and in vitro antimalarial activity--Part II.

Following our search for antimalarial compounds, novel series of ferrocenyl-substituted pyrrolo[1,2-a]quinoxalines 1-2 were synthesized from ferrocene-carboxaldehyde and tested for their in vitro activity upon the erythrocytic development of Plasmodium falciparum strains with different chloroquine-resistance status. The ferrocenic pyrrolo[1,2-a]quinoxalines 1-2 were prepared in 6 or 9 steps through a Barton-Zard reaction. Promising pharmacological results against FcB1, K1 and F32 strains were obtained with ferrocenyl pyrrolo[1,2-a]quinoxalines 1j-l linked by a bis-(3-aminopropyl)piperazine linker substituted by a nitrobenzyl moiety.

Relative helix-helix conformations in branched aromatic oligoamide foldamers.

The de novo design and synthesis of large and well-organized, tertiary-like, α-peptidic folded architectures is difficult because it relies on multiple cooperative interactions within and between secondary folded motifs of relatively weak intrinsic stability. The very stable helical structures of oligoamides of 8-amino-2-quinoline carboxylic acid offer a way to circumvent this difficulty thanks to their ability to fold into predictable and stable secondary motifs. Branched architectures comprised of two pairs of tetrameric (1), pentameric (2), or octameric (3) oligomers connected via an ethylene glycol spacer were designed and synthesized.

Antiproliferative effect on HepaRG cell cultures of new calix[4]arenes. Part II.

Cell cycle progression is dependent on the intracellular iron level and chelators can lead to iron depletion and decrease cell proliferation. This antiproliferative effect can be inhibited by exogenous iron. In this work, we present the synthesis of some new synthetic calix[4]arene podands bearing diamino-tetraesters, diamino-tetraalcohols, diamino-tetraacid and tetraaryloxypentoxy groups at the lower rim, designed as potential iron chelators.

Efficient pallado-catalyzed C6-(het)arylation of Imidazo[1,2-b][1,2,4,5]tetrazines under microwave irradiations.

A versatile protocol for the preparation of a library of 5,6-(het)bisarylated imidazo[1,2-b][1,2,4,5]tetrazines is described. Target compounds were obtained in fairly good yields, starting from ethoxy-7-(4-methoxyphenyl)imidazo[1,2-b][1,2,4,5]tetrazine and a large panel of bromoaryl derivatives, using palladium catalysis under microwave irradiation. Compatibility with various chemical groups and heterocycles was proven.

Lidocaine/L-menthol binary system: cocrystallization versus solid-state immiscibility.

We present the synthesis, structure determination, and thermodynamic properties of a never reported cocrystal prepared with lidocaine and L-menthol. The temperature-composition phase diagram of the lidocaine/L-menthol binary system was achieved using differential scanning calorimetry and X-ray diffraction experiments. The present study demonstrates that the only way to perform a phase equilibrium survey of the lidocaine/L-menthol system is to prepare the binary mixtures from the cocrystal, an equimolar stoichiometric compound of L-menthol and lidocaine.

Hybridization of long pyridine-dicarboxamide oligomers into multi-turn double helices: slow strand association and dissociation, solvent dependence, and solid state structures.

Oligoamides of 2,6-diaminopyridine and 2,6-pyridinedicarboxylic acid comprised of 5, 7, 9, 11, or 13 units and bearing 4-isobutoxychains on all pyridine rings and tert-butyl-carbamate terminal groups have been synthesized stepwise, along with an 11 mer having benzyl-carbamate terminal groups. The crystal structure of all five Boc-terminated compounds has been obtained and shows a highly regular and conserved double helical hybridization motif of up to 3 complete turns for the 13 mer. Four pyridine units span one helical turn and define a helix pitch of ca 7 A.

(Thio)Amidoindoles and (thio)amidobenzimidazoles: an investigation of their hydrogen-bonding and organocatalytic properties in the ring-opening polymerization of lactide.

The mechanism of the ring-opening polymerization (ROP) of lactide catalyzed by two partner hydrogen-bonding organocatalysts was explored. New amidoindoles 4 a,c, thioamidoindoles 4 b,d, amidobenzimidazoles 5 a,c, and thioamidobenzimidazoles 5 b,c were synthesized and used as activators of the monomer. In the solid state and in solution, compounds 4 and 5 showed a propensity for self-association, which was evaluated.

3-[2-(1H-Benzimidazol-2-ylsulfan-yl)eth-yl]-1,3-oxazolidin-2-one.

In the title compound, C(12)H(13)N(3)O(2)S, the oxazolidin ring displays an envelope conformation. The dihedral angle between the benzimidazole ring and the 1,3-oxazolidin-2-one mean plane is 69.85 (13)°.

Synthesis and in vitro cytostatic activity of new beta-D-arabino furan[1',2':4,5]oxazolo- and arabino-pyrimidinone derivatives.

A series of nucleoside derivatives was obtained via heteroatom annulation of the amino oxazoline of D-(-)-arabinose. Unequivocal proofs for the stereostructure of some new arabinosyl pyrimidinone derivatives were obtained by X-ray structure analysis. These newly synthesized compounds were then evaluated for their cytostatic activity against murine leukemia (L1210), and human T-lymphocytes (Molt 4/C8 and CEM).

Antiproliferative effect on HepaRG cell cultures of new calix[4]arenes.

Cell cycle progression is dependent on the intracellular iron level, and chelators lead to iron depletion and decrease cell proliferation. This antiproliferative effect can be inhibited by exogenous iron. In this work, we present the synthesis of new synthetic calix[4]arene podands bearing alkyl acid and alkyl ester groups at the lower rim, designed as potential iron chelators.

Smiles rearrangement as a tool for the preparation of dihydrodipyridopyrazines.

A novel methodology for the synthesis of isomer A of dihydrodipyridopyrazines was developed. The key transformation features a Smiles rearrangement of nitro substituted N,N'-dipyridinylamines, potential precursors of isomer B obtained by the alkylation of compounds prepared by a Pd-catalyzed reaction and subsequent cyclization.

Ring-opening polymerization of L-lactide efficiently triggered by an amido-indole. X-ray structure of a complex between L-lactide and the hydrogen-bonding organocatalyst.

N-(3,5-Bis(trifluoromethyl)phenyl)-1H-indole-2-carboxamide 1e is an efficient hydrogen-bonding organocatalyst for the ring-opening polymerization of l-lactide. This new catalytic species does control the dispersity (1.08) and molecular weight (3460 g/mol vs 3064 in theory) of the poly(l-lactides) prepared in 2 h.

Cylindrical sheet formation of oligo-meta-aniline foldamers.

Ortho-nitro- and ortho-alkoxy-oligo-meta-aniline units fold in solution through hydrogen bonds and aromatic stacking into compact structures that were characterized in the solid state as cylindrical beta-sheet like structures.

Striking correlation between the unusual trigonal crystal packing and the ability to self-assemble into nanofibers of 2,3-di-n-alkyloxyanthracenes.

The space group of the crystals of derivatives of 2,3-dialkoxyanthracenes is monoclinic P2(1)/a (herringbone structure) with the linear ethyl or propyl chains but abruptly changes to the trigonal P3 or R3 space group for butyl to heptyl chains. Strikingly, this switch is correlated with the capacity of these compounds to self-assemble into nanofibers and organogels. Besides, compounds with a chain length exceeding seven carbon atoms could not be crystallized in accordance with the analysis of the projected crystal structure but are nevertheless excellent organogelators.

Remote substituent effects and regioselective enhancement of electrophilic substitutions in helical aromatic oligoamides.

The bromination of helically folded oligoamides of 8-amino-4-isobutoxy-2-quinolinecarboxylic acid by N-bromosuccinimide has been investigated. Bromination occurs preferentially if not exclusively at one position in the sequence despite the presence of multiple, up to seven, a priori comparable, reaction sites. Reactions are up to 2 orders of magnitude faster in a folded octamer than in a short nonhelical dimer, despite the steric hindrance that is expected in a compact folded conformation.

Interpenetrating single helical capsules.

An aromatic oligoamide sequence designed to adopt a helically folded conformation surrounding a hollow space is shown to undergo hybridization into a double helical duplex in which the two strands fill each other's hollow.

Expanding the registry of aromatic amide foldamers: folding, photochemistry and assembly using diaza-anthracene units.

The synthesis of various 1,8-diaza-4,5-dialkoxy-2,7-anthracene dicarboxylic acid derivatives and their incorporation into cyclic and helically folded aromatic oligoamides are reported. The ability of the diaza-anthracene monomers to undergo photoaddition or head-to-tail photodimerization was investigated in the solid state and in solution. Quantitative conversion of a monomer diester to the corresponding head-to-tail photodimer could be achieved in the solid state without protection from oxygen.