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Université de Fribourg

Cell-Permeant and photocleavable chemical inducer of dimerization

Zimmermann, Mirjam ; Cal, Ruben ; Janett, Elia ; Hoffmann, Viktor ; Bochet, Christian G. ; Constable, Edwin ; Beaufils, Florent ; Wymann, Matthias P.

In: Angewandte Chemie International Edition, 2014, vol. 53, no. 18, p. 4717–4720

Chemical inducers of dimerization (CIDs) have been developed to orchestrate protein dimerization and translocation. Here we present a novel photocleavable HaloTag- and SNAP-tag-reactive CID (MeNV-HaXS) with excellent selectivity and intracellular reactivity. Excitation at 360 nm cleaves the methyl-6-nitroveratryl core of MeNV-HaXS. MeNV-HaXS covalently links HaloTag- and SNAP-tag fusion...

Université de Fribourg

Secondary metabolites from Triclisia gilletii (De Wild) Staner (Menispermaceae) with antimycobacterial activity against Mycobacterium tuberculosis

Tiam, Eric Robert ; Ngono Bikobo, Dominique Serge ; Zintchem, Auguste Abouem A. ; Mbabi Nyemeck II, Norbert ; Moni Ndedi, Esther Del Florence ; Betote Diboué, Patrick Hervé ; Nyegue, Maximilienne Ascension ; Atchadé, Alex de Théodore ; Pegnyemb, Dieudonné Emmanuel ; Bochet, Christian G. ; Koert, Ulrich

In: Natural Product Research, 2019, vol. 33, no. 5, p. 642–650

Triclisinone (2), a new ochnaflavone derivative, was isolated from the aerial parts of Triclisia gilletii, along with known drypemolundein B (1) and eight other known compounds. The chemical shifts of drypemolundein B (1) have been partially revised based on reinterpretation of NMR spectroscopic data. The eight other secondary metabolites are composed of: (+)-nonacosan-10-ol (3); stigmasterol...

Université de Fribourg

Hydrogen bond stabilization in Diels–Alder transition states: The cycloaddition of hydroxy-ortho-quinodimethane with fumaric acid and dimethylfumarate

Tamilmani, Venkatachalam ; Daul, Claude A. ; Lage Robles, Jaime ; Bochet, Christian G. ; Venuvanalingam, P.

In: Chemical Physics Letters, 2005, vol. 406, no. 4, p. 355-359

DFT investigations on the mechanism of Diels–Alder reactions of a hydroxy-ortho-quinodimethane with fumaric acid derivatives were performed to understand the origin of the syn or anti configuration of the adducts. The diene hydroxyl group and the dieneophile carboxyl group show hydrogen bonding in the transition state, significantly favouring the syn product. This reaction is poorly...

Université de Fribourg

The arene–alkene photocycloaddition

Streit, Ursula ; Bochet, Christian G.

In: Beilstein Journal of Organic Chemistry, 2011, vol. 7, p. 525–542

n the presence of an alkene, three different modes of photocycloaddition with benzene derivatives can occur; the [2 + 2] or ortho, the [3 + 2] or meta, and the [4 + 2] or para photocycloaddition. This short review aims to demonstrate the synthetic power of these photocycloadditions.

Université de Fribourg

The photocycloaddition of arenes and allenes

Streit, Ursula ; Birbaum, Frédéric ; Quattropani, Anna ; Bochet, Christian G.

In: The Journal of Organic Chemistry, 2013, p. -

In the present work, we report on a new intramolecular para-cycloaddition of arenes with allenes, yielding attractive rigid scaffolds bearing several reactive functionalities to build in further diversity. Bicyclo[2.2.2]octadiene-type products and benzoxepine acetals are formed in this reaction, in ratios and yields depending on the substitution pattern on the aromatic ring, the nature of the...

Université de Fribourg

The ABC transporter BcatrB from Botrytis cinerea exports camalexin and is a virulence factor on Arabidopsis thaliana

Stefanato, Francesca L. ; Abou-Mansour, Eliane ; Buchala, Antony ; Kretschmer, Matthias ; Mosbach, Andreas ; Hahn, Matthias ; Bochet, Christian G. ; Métraux, Jean-Pierre ; Schoonbeek, Henk-jan

In: The Plant Journal, 2009///doi: 10.1111/j.1365-313X.2009.03794.x

Arabidopsis thaliana is known to produce the phytoalexin camalexin in response to abiotic and biotic stress. Here we studied the mechanisms of tolerance to camalexin in the fungus Botrytis cinerea, a necrotrophic pathogen of A. thaliana. Exposure of B. cinerea to camalexin induces expression of BcatrB, an ABC transporter that functions in the efflux of fungitoxic compounds. B. cinerea inoculated...

Université de Fribourg

Photolysis of ortho-nitrobenzylic derivatives: the importance of the leaving group

Šolomek, Tomáš ; Mercier, Sébastien ; Bally, Thomas ; Bochet, Christian G.

In: Photochemical & Photobiological Sciences, 2012, vol. 11, no. 3, p. 548-555

Quantum yields for the photoinduced release of seven different commonly used leaving groups (LGs) from the o-nitroveratryl protecting group were measured. It was found that these quantum yields depend strongly on the nature of the LGs. We show that the quantum efficiency with which the LGs are released correlates with the stabilization that these LGs provide to o-nitrobenzyl-type radicals because...

Université de Fribourg

The Primary steps in excited-state hydrogen transfer: the phototautomerization of o-nitrobenzyl derivatives

Šolomek, Tomáš ; Bochet, Christian G. ; Bally, Thomas

In: Chemistry – A European Journal, 2014, vol. 20, no. 26, p. 8062–8067

The quantum yield for the release of leaving groups from o-nitrobenzyl “caged” compounds varies greatly with the nature of these leaving groups, for reasons that have never been well understood. We found that the barriers for the primary hydrogen-atom transfer step and the efficient nonradiative processes on the excited singlet and triplet surfaces determine the quantum yields. The...

Université de Fribourg

New safety-catch photolabile protecting group

Riguet, Emmanuel ; Bochet, Christian G.

In: Organic Letters, 2007, vol. 9, no. 26, p. 5453 -5456

Photolabile protecting groups have proven their usefulness on many occasions. Their versions as linkers are however less attractive, as robustness and real orthogonality become critical issues. Safety-catch systems, where a preliminary activation phase is necessary, circumvent the problem of premature cleavage. In this work, we introduce a new safety-catch photolabile protecting group, whose...

Université de Fribourg

Application of photoclick chemistry for the synthesis of pyrazoles via 1,3‐dipolar cycloaddition between alkynes and nitrilimines generated in situ

Remy, Richard ; Bochet, Christian G.

In: European Journal of Organic Chemistry, 2018, vol. 2018, no. 3, p. 316–328

The photochemical extrusion of gaseous nitrogen from 2,5-disubstituted tetrazoles to generate reactive nitrilimines in situ represents an efficient and attractive way to form dipoles that can be used to provide useful chemicals via 1,3-dipolar cycloadditions. The concept of “photoclick chemistry” already inspired numerous researchers, who exploited photochemical processes involving...