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European Journal of Organic Chemistry

Julia Weber, Markus Schwarz, Andrea Schiefer, Christian Hametner, Georg Häubl, Johannes Fröhlich, Hannes Mikula
The synthesis of (2-nitrophenyl)acetyl (NPAc)-protected glucosyl donors is described that were designed for the neighboring-group assisted glucosylation of base-labile natural products also being sensitive to hydrogenolysis. Glycosylation conditions were optimized using a trichloroacetimidate glucosyl donor, and cyclohexylmethanol and (+)-menthol as model acceptors. The approach was then extended to a one-pot procedure for the synthesis of 1,2- trans -glycosides. This method was finally applied for improved synthesis of the masked mycotoxin T2- O -β,d-glucoside...
June 7, 2018: European Journal of Organic Chemistry
Sarah H Hewitt, Andrew J Wilson
Dynamic combinatorial chemistry (DCC) represents an approach, whereby traditional supramolecular scaffolds used for protein surface recognition might be exploited to achieve selective high affinity target recognition. Synthesis, in situ screening and amplification under selection pressure allows the generation of ligands, which bear different moieties capable of making multivalent non-covalent interactions with target proteins. Generic tetracarboxyphenyl porphyrin scaffolds bearing four hydrazide moieties have been used to form dynamic combinatorial libraries (DCLs) using aniline-catalyzed reversible hydrazone exchange reactions, in 10 % DMSO, 5 mm NH4 OAc, at pH 6...
April 30, 2018: European Journal of Organic Chemistry
Bo Yang, Weizhun Yang, Sherif Ramadan, Xuefei Huang
Due to the wide presence of carbohydrates in nature and their crucial roles in numerous important biological processes, oligosaccharides have attracted a lot of attention in synthetic organic chemistry community. Many innovative synthetic methods have been developed for oligosaccharide synthesis, among which the pre-activation based glycosylation is particularly noteworthy. Traditionally, glycosylation reactions are carried out when the glycosyl donor and the acceptor are both present when the promoter is added...
March 7, 2018: European Journal of Organic Chemistry
Michael Winter, Christina Gaunersdorfer, Lukas Roiser, Katharina Zielke, Uwe Monkowius, Mario Waser
The use of carbonyl-stabilized ammonium- and sulfonium ylides allows for the synthesis of highly-functionalized trifluoroacetyl-substituted cyclopropanes. It turned out that the diastereoselectivities strongly depend on the nature of the chosen ylide and the employed base. The products could be obtained in good yields under operationally simple conditions.
January 23, 2018: European Journal of Organic Chemistry
Francesco Mecozzi, Jia Jia Dong, Pattama Saisaha, Wesley R Browne
α-Hydroxy ketones are valuable synthons in organic chemistry. Here we show that oxidation of vic -diols to α-hydroxy ketones with H2 O2 can be achieved with an in situ prepared catalyst based on manganese salts and pyridine-2-carboxylic acid. Furthermore the same catalyst is effective in alkene epoxidation, and it is shown that alkene oxidation with the MnII catalyst and H2 O2 followed by Lewis acid ring opening of the epoxide and subsequent oxidation of the alkene to α-hydroxy ketones can be achieved under mild (ambient) conditions...
December 15, 2017: European Journal of Organic Chemistry
Robert D Armstrong, Benson M Kariuki, David W Knight, Graham J Hutchings
Glucaric acid has potential applications in food, pharmaceutical and polymer industries yet no methodology exists within the public domain for isolation of this key bio-derived platform molecule as a pure, crystalline solid. Here we demonstrate the difficulties, which arise in doing so and report development of a process for derivation of free-glucaric acid from its Ca2+ /K+ glucarate salts, which are both commercially available. Employing Amberlyst-15 (H+ ) exchange resin and azeotrope drying, powdered glucaric acid is prepared at > 99...
December 8, 2017: European Journal of Organic Chemistry
Gregory R Naumiec, Lisheng Cai, Shuiyu Lu, Victor W Pike
Positron emission tomography (PET) is an important molecular imaging technique for medical diagnosis, biomedical research and drug development. PET tracers for molecular imaging contain β+ -emitting radionuclides, such as carbon-11 ( t 1/2 = 20.4 min) or fluorine-18 ( t 1/2 = 109.8 min). The [18 F]2-fluoro-pyridyl moiety features in a few prominent PET radiotracers, not least because this moiety is usually resistant to unwanted radiodefluorination in vivo. Various methods have been developed for labeling these radiotracers from cyclotron-produced no-carrier-added [18 F]fluoride ion, mainly based on substitution of a leaving group, such as halide (Cl or Br), or preferably a better leaving group, such as nitro or trimethylammonium...
December 8, 2017: European Journal of Organic Chemistry
Ihsan Erden, Christian Gärtner, Jingxiang Ma, Gabriel Cabrera, Kate Markham, Saeed Azimi, Scott Gronert
Aldonitrones derived from spiro[2.4]hepta-4,6-diene-1-carbaldehyde and its benzo analog undergo a tandem uncatalyzed intramolecular cyclopropane-nitrone cyclization-5,6-dihydro-1,2-oxazine cycloreversion to give cyclopentadienones. Similarly, the NH-nitrone generated in situ from spiro[cyclopropane-1,1'-indene]carbaldehyde oxime leads to benzocyclopentadienone (1 H -inden-1-one) by the same mechanism. DFT calculations are in favor of a concerted yet highly asynchronous pathway for the cyclizations. Control experiments with the dihydro and tetrahydro derivatives show that the spirocyclopentadiene unit is essential for the success of the reaction, invoking spiroconjugative effects for increased cyclopropane reactivity...
September 15, 2017: European Journal of Organic Chemistry
Bojan Vulovic, Donald A Watson
Since the discovery of the Heck reaction in the early seventies, this reaction has become a powerful tool in synthetic organic chemistry. By employing heteroatomic instead of traditional carbon electrophiles, the Heck reaction shows an intriguing flexibility. These "hetereoatomic-Heck reactions" reinvigorate the area, offering new routes to highly useful synthetic precursors and structural motifs present in biologically active compounds. This microreview focuses on early developments leading to the heteroatomic-Heck reactions (silyl-Heck, boryl-Heck and intramolecular aza-Heck), current state of the emerging area, as well as that of a few related processes...
September 15, 2017: European Journal of Organic Chemistry
Stephen J Chawner, Manuel J Cases-Thomas, James A Bull
Cyclopropanes provide important design elements in medicinal chemistry and are widely present in drug compounds. Here we describe a strategy and extensive synthetic studies for the preparation of a diverse collection of cyclopropane-containing lead-like compounds, fragments and building blocks exploiting a single precursor. The bifunctional cyclopropane (E/Z)-ethyl 2-(phenylsulfanyl)-cyclopropane-1-carboxylate was designed to allow derivatization through the ester and sulfide functionalities to topologically varied compounds designed to fit in desirable chemical space for drug discovery...
September 15, 2017: European Journal of Organic Chemistry
Gregory J P Perry, Igor Larrosa
The beginning of the 21st century has seen tremendous growth in the field of decarboxylative activation. Benzoic acid derivatives are now recognised as atom-economic alternatives to traditional cross-coupling partners, and they also benefit from being inexpensive, readily available and shelf-stable reagents. In this microreview we discuss recent developments in the coupling of benzoic acid derivatives either with an arene or with a second benzoic acid derivative, a process often termed decarboxylative oxidative cross-coupling...
July 7, 2017: European Journal of Organic Chemistry
Lorenzo Cavina, Dion van der Born, Peter H M Klaren, Martin C Feiters, Otto C Boerman, Floris P J T Rutjes
Radioiodinated pharmaceuticals are convenient tracers for clinical and research investigations because of the relatively long half-lives of radioactive iodine isotopes (i.e., (123)I, (124)I, and (131)I) and the ease of their chemical insertion. Their application in radionuclide imaging and therapy may, however, be hampered by poor in vivo stability of the C-I bond. After an overview of the use of iodine in biology and nuclear medicine, we present here a survey of the catabolic pathways for iodinated xenobiotics, including their biodistribution, accumulation, and biostability...
June 30, 2017: European Journal of Organic Chemistry
Ihsan Erden, Scott Gronert, Gabriel Cabrera, Necdet Coskun, Marco Tapken
The title compound exhibits a number of reactivities toward nucleophiles/bases owing to the presence of several electrophilic and potentially nucleophilic sites in the molecule. We explored the reactions of 6-(chloromethyl)-6-methylfulvene with oxygen- and nitrogen nucleophiles and bases as well as a carbon-based nucleophile (an enamine) and realized all possible reactivity modes predicted on the basis of electrophilic and nucleophilic positions in this compound.
May 26, 2017: European Journal of Organic Chemistry
Daniel Rackl, Viktor Kais, Eugen Lutsker, And Oliver Reiser
The synthesis of chiral tetrahydrofurans and pyrrolidines starting from 1,2-diols or β-amino alcohols, respectively, by visible-light-mediated deoxygenation is described. Easily accessible monoallylated/propargylated substrates were activated either as inexpensive ethyl oxalates or as recyclable 3,5-bis(trifluoromethyl)benzoates to generate alkyl radicals suitable for 5-exo-trig/5-exo-dig cyclizations under visible-light irradiation.
April 18, 2017: European Journal of Organic Chemistry
Gregg M Schwarzwalder, Christopher D Vanderwal
The halenaquinol family of naphthoquinol natural products includes a few closely related polycyclic compounds that feature an activated, electrophilic furan ring. This motif is likely responsible for the rich biological activity attributed to these secondary metabolites. Their interesting structures-related via their electrophilic furan to the biologically important furanosteroids-and their activities prompted significant efforts by organic chemists that resulted in many strategically compelling laboratory syntheses of these targets...
March 27, 2017: European Journal of Organic Chemistry
Matthew A Horwitz, Jeffrey S Johnson
The application of desymmetrization strategies in chemical synthesis has allowed fundamentally new synthetic sequences that efficiently create dense and polyfunctional stereochemical arrays. Enantiotopic group discrimination has become a well-established method of global desymmetrization, while the conceptually unique strategy of local desymmetrization by diastereotopic group discrimination has its own advantages. This microreview focuses on the application of local desymmetrization in natural product synthesis and places a particular emphasis on the efficiency engendered by diastereotopic group discrimination...
March 17, 2017: European Journal of Organic Chemistry
Răzvan C Cioc, Verónica Estévez, Daan J van der Niet, Christophe M L Vande Velde, Nikolaus G Turrini, Mélanie Hall, Kurt Faber, Eelco Ruijter, Romano V A Orru
We report the use of bifunctional starting materials (ketoacids) in a diastereoselective Passerini three-center-two-component reaction. Study of the reaction scope revealed the required structural features for stereoselectivity in the isocyanide addition. In this system, an interesting isomerization of the primary Passerini product - the α-carboxamido lactone - into an atypical product, an α-hydroxy imide, was found to occur under acidic conditions. Furthermore, enantioenriched Passerini products can be generated from an enantioenriched ketoacid obtained by chemoenzymatic synthesis...
March 3, 2017: European Journal of Organic Chemistry
Monalisa Goswami, Bas de Bruin
The azide moiety is a desirable functionality in organic molecules, useful in a variety of transformations such as olefin aziridination, C-H bond amination, isocyanate synthesis, the Staudinger reaction and the formation of azo compounds. To harness the versatility of the azide functionality fully it is important that these compounds be easy to prepare, in a clean and cost-effective manner. Conventional (non-catalysed) methods to synthesise azides generally require quite harsh reaction conditions that are often not tolerant of functional groups...
February 24, 2017: European Journal of Organic Chemistry
Xiaoping Tang, Rudolf K Allemann, Thomas Wirth
Sesquiterpenes are an important family of natural products, many of which exhibit important pharmaceutical and agricultural properties. They are biosynthesised from farnesyl diphosphate in sesquiterpene synthase catalysed reactions. Here, we report the development of a highly efficient segmented flow system for the enzyme-catalysed continuous flow production of sesquiterpenes. Design of experiment (DoE) methods were used to optimise the performance of the flow biocatalysis, and quantitative yields were achieved by using an operationally simple but highly effective segmented flow system...
January 10, 2017: European Journal of Organic Chemistry
Ashley M Dreis, Sadie C Otte, Matthew S Eastwood, Elizabeth R Alonzi, Jason T Brethorst, Christopher J Douglas
Reported herein is a diastereoselective intramolecular alkene cyanoamidation, wherein high d.r. values are imparted by chiral directing groups. Lactams with an α-all-carbon quaternary stereocenter are readily synthesized, which may enable access to structures frequently found in biologically active molecules and natural products.
January 3, 2017: European Journal of Organic Chemistry
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