Synthesis and Photophysical Properties of 1,1,4,4-Tetracyanobutadienes Derived from Ynamides Bearing Fluorophores**

1,1,4,4-Tetracyanobutadienes (TCBDs) bearing a large diversity of fluorophores were prepared following a multi-step synthesis. In a crucial last step, all compounds were obtained from the corresponding ynamides, which were particularly suitable for the formation of the TCBDs in the presence of tetracyanoethylene via a [2+2] cycloaddition/retroelectrocyclization step (CA-RE). Several fluorenyl derivatives in addition to phenanthrenyl and terphenyl ones provided ynamide-based TCBDs affording remarkable emission properties covering a large range of wavelengths. Those compounds emit both in solid state and in solution from the visible region to the NIR range, depending on the molecular structures. Quantum yields in cyclohexane reached unforeseen values for such derivatives, up to 7.8 %. A huge sensitivity to the environment of the TCBDs has also been unraveled for most of the compounds since we observed a dramatic fall of the quantum yields when changing the solvent from cyclohexane to toluene, while they are almost non-emissive in dichloromethane.     

Gold‐ and Platinum‐Catalyzed Cycloisomerization of Enynyl Esters versus Allenenyl Esters: An Experimental and Theoretical Study

Ester‐way to heaven : Unexpected formation of bicyclo[3.1.0]hexene 4 was the main focus of combined experimental and theoretical studies on the Au‐catalyzed cycloisomerization of branched dienyne 1 (see scheme), which provided better understanding of the mechanistic details governing the cyclization of enynes bearing a propargylic ester group.

     

Thermal/hyperbaric heterocycloaddition of 1,4-dialkoxy-1,3-dienes: the de novo (E,Z) way to sugars

1-(Z)-Alkoxy-4-(E)-methoxybutadiene derivatives have been reacted with ethylgyoxylate and diethyl ketomalonate under thermal or hyperbaric conditions. They provide, with a total regioselectivity and fair to total endoselectivities, the expected dihydropyranic cycloadducts. Three of those pseudo-glycals have been converted in a few classical steps (deprotection, reduction, and dihydroxylation) into (racemic) allose, mannose, and gullose derivatives. The order of these three steps has a direct influence on the efficiency of the transformation and determines the stereochemistry of the final sugar.     

Synthesis of archaeal bipolar lipid analogues: a way to versatile drug/gene delivery systems

A synthetic route for the preparation of symmetrical and unsymmetrical archaeal tetraether-like analogues has been described. The syntheses are based upon the elaboration of hemimacrocyclic tetraether lipid cores from versatile building blocks followed by simultaneous or sequential introduction of polar head groups. Functionalizations of the tetraether lipids with neutral lactose or phosphatidylcholine polar heads and cationic glycine betaine moieties were envisaged both to increase membrane stability and to exhibit interactions with charged nucleic acids. Additionally, mannose and lactose triantennary clusters designed as multivalent ligands for selective interaction with lectin-type receptors were also efficiently synthesized for active cell/tissue targeting.     

Synthesis and stacked conformations of symmetrical and unsymmetrical oligo-ureas of metaphenylenediamine

The addition of substituted anilines to nitro-substituted isocyanates followed by reduction generates new aniline-substituted ureas, which can be further extended in a one- or two-directional iterative manner to form oligomeric ureas based on a m-phenylenediamine monomer. Oligo-ureas with up to eight urea linkages are reported. Fully N-substituted oligo-ureas are crystalline, and the X-ray crystal structures display ring-stacked conformations. 1H NMR studies indicate that the stacked conformation persists in solution.     

Mass spectrometric identification of Rab23 phosphorylation as a response to challenge by cytidine 3',5'-cyclic monophosphate in mouse brain

While the functions and mechanisms of action of adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) are well established and are the basis of the action of a large number of successful pharmaceuticals, the role of a third naturally occurring cyclic nucleotide, cytidine 3',5'-cyclic monophosphate (cCMP), remains to be elucidated. Immobilized metal affinity chromatography (IMAC) was used to selectively extract proteins phosphorylated in mouse brain in response to challenge by cAMP, cGMP and cCMP, followed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-ToFMS) and liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) of tryptic digests to identify Rab23 as the first protein reported to be phosphorylated only in response to cCMP.     

Synthesis of novel 5‐aryl‐1H‐tetrazoles

In this study phenylselenocyanate and some of its derivatives (o‐Cl, p‐Cl, p‐Br, o‐NO₂, p‐NO₂, o‐CH₃, p‐CH₃, o‐COOH, p‐COOH, p‐OCH₃ substituted) were synthesized ( 3a–3j ). The synthesized compounds were converted to 5‐aryl‐1H‐tetrazole ( 4a–4j ), by Et₃N ċ HCl‐NaN₃ in toluene, which are a new series of phenylselanyl‐1H‐tetrazoles. The structure of all the presently synthesized compounds were confirmed using spectroscopic methods (FTIR, ¹H NMR, MS). © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:255–258, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20293     

Identification of substances migrating from plastic baby bottles using a combination of low‐resolution and high‐resolution mass spectrometric analysers coupled to gas and liquid chromatography

This work presents a strategy for elucidation of unknown migrants from plastic food contact materials (baby bottles) using a combination of analytical techniques in an untargeted approach. First, gas chromatography (GC) coupled to mass spectrometry (MS) in electron ionisation mode was used to identify migrants through spectral library matching. When no acceptable match was obtained, a second analysis by GC‐(electron ionisation) high resolution mass spectrometry time of flight (TOF) was applied to obtain accurate mass fragmentation spectra and isotopic patterns. Databases were then searched to find a possible elemental composition for the unknown compounds. Finally, a GC hybrid quadrupole‐TOF‐MS with an atmospheric pressure chemical ionisation source was used to obtain the molecular ion or the protonated molecule. Accurate mass data also provided additional information on the fragmentation behaviour as two acquisition functions with different collision energies were available (MS^E approach). In the low‐energy function, limited fragmentation took place, whereas for the high‐energy function, fragmentation was enhanced. For less volatile unknowns, ultra‐high pressure liquid chromatography‐quadrupole‐TOF‐MS was additionally applied. Using a home‐made database containing common migrating compounds and plastic additives, tentative identification was made for several positive findings based on accurate mass of the (de)protonated molecule, product ion fragments and characteristic isotopic ions. Six illustrative examples are shown to demonstrate the modus operandi and the difficulties encountered during identification. The combination of these techniques was proven to be a powerful tool for the elucidation of unknown migrating compounds from plastic baby bottles. Copyright © 2015 John Wiley & Sons, Ltd.     

Analysis of urinary nucleosides. V. Identification of urinary pyrimidine nucleosides by liquid chromatography/electrospray mass spectrometry

Modified urinary nucleosides are potentially invaluable in cancer diagnosis, as they reflect altered RNA turnovers. High-performance liquid chromatography (HPLC) was combined with full-scan mass spectrometry, tandem mass spectrometry, MS(n) analysis and accurate mass measurements in order to identify pyrimidine nucleosides purified from urine. Potential nucleosides were assessed by their evident UV absorbance in the HPLC chromatogram and then further examined by the various mass spectrometric techniques. In this manner numerous pyrimidine nucleosides were identified in the urine samples from cancer patients including pseudouridine, cytidine, two methylcytidines and an acetylcytidine. Furthermore, a number of novel modified pyrimidine nucleosides were tentatively identified via critical interpretation of the combined mass spectrometric data.     

Boron Effect on Sugar-Based Organogelators

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.