Alcohol uncaging with fluorescence reporting: evaluation of o-acetoxyphenyl methyloxazolone precursors

This paper evaluates a series of photolabile protecting groups with built-in fluorescence reporting. They rely on readily available o-acetoxyphenyl methyloxazolones as activated precursors. Alcohol substrates are easily caged. The resulting photoactivable esters exhibit large one- and two-photon uncaging cross sections. The alcohol substrates are quantitatively released in a 1:1 molar ratio with a strongly fluorescent coumarin coproduct that serves as a reporter to quantify substrate delivery.     

Sub-picosecond ballistic imaging of a liquid jet

A diesel jet visualisation based on an ultra-short light pulse and a time-resolved detection is proposed. An optical gate, consisting of a beta barium borate crystal, allows to separate ballistic, refractive and scattered light. An imaging pulse passes through the studied medium, while a gating pulse is used to open the gate. With this configuration, a spatial resolution of 10 μm and a temporal resolution of 270 fs are obtained. The gate duration is compatible with the typical dimensions of a liquid jet generated by a commercial automotive fuel injector. Preliminary results show that spatio-temporal diagrams of transmitted light through a spray may be acquired, showing clearly the separation between ballistic, refracted and scattered light.     

Application de la réaction de Wittig à la synthèse de dérivés de bromoénosuloses et d'esters bromoénuroniques. Note de laboratoire

Use of the Wittig reaction for the synthesis of derivatives of bromoenosuloses and bromoenuronic esters Treatment of 3-O-benzyl (or 3-O-methyl)-1, 2-O-isopropylidene-α-D -xylo-pentodialdo-1, 4-furanoses ( 2 or 1 ) with acetylbromomethylidenetriphenylphosphorane ( 3 ), benzoylbromomethylidenetriphenylphosphorane ( 4 ) or bromoethoxycarbonylmethylidenetriphenylphosphorane ( 5 ) gave in good to excellent yields the expected enose ( 6--11 ). In all cases but one ( 8 where some 10% of the E-isomer was formed) the reaction led to the exclusive formation of the Z-isomer whose configuration was established by NMR.     

Etudes sur les composés organométalliques. XVII. Synthèse du tétracyclohexyltitane

Studies of Organometallic Compounds. XVII Synthesis of Tetracyclohexyltitanium Tetracyclohexyltitanium is prepared by reaction of TiCl₄ or Ti(OC₄H₉)₄ with dicyclohexylmagnesium in pentane or ether at - 30°. Some aspects of its reactivity and its decomposition are described.     

Utilisation de techniques d'amination réductrice pour la synthèse d'amino-sucres de différents types. Communication préliminaire

Synthesis of amino-sugars using reductive amination reactions. Preliminary communication Treatment of aldehydo- or keto-sugars with primary or secondary amines and hydrogen in the presence of a catalyst (Pd/C) gave with good to excellent yields (67–96%) the expected secondary or tertiary amines. Primary amines can be obtained by using benzylamine, a hydrogenolysis taking place during the reaction.     

Préparation de dérivés de sucres acétyléniques terminaux et d'acides ynuroniques par réaction de Wittig. Note de laboratoire

Synthesis of Terminal Acetylenic Sugars Derivatives and Ynuronic Acids Derivatives by Use of a Wittig Reaction The method described for the preparation of terminal acetylenic sugars presents two advantages over earlier procedures: no new asymmetric center is created and the chain can be extended by one or more C-atoms. The method also allows preparation of ynuronic acids. The aldehydosugars derivatives 1–7 gave in good to excellent yields the corresponding gem-dibromoenoses 8–14 from which either the terminal acetylenic sugars derivatives 15–21 or the ynuronic acids 22–24 were easily prepared. A few examples of 1,3-dipolar cycloadditions (leading to 28–30 ) with these acetylenic sugar derivatives are also described.     

Synthesis and l-fucosidase inhibitory activity of a new series of cyclic sugar imines—in situ formation and assay of their saturated counterparts

The synthesis of a series of aryl-substituted cyclic sugar imines was performed via a tandem nucleophilic addition/substitution reaction. The so-obtained ketimines displayed fucosidase inhibitory activities (IC₅₀ = 46-556 μM). Their reduced counterparts were prepared and assayed after addition of sodium borohydride to the enzymatic assay stock solution. The pyrrolidines strongly inhibit fucosidase (IC₅₀ = 0.65-150 μM).