A highly efficient TEMPO mediated oxidation of sugar primary alcohols into uronic acids using 1-chloro-1,2-benziodoxol-3(1H)-one at room temperature

Oxidation of various sugar primary alcohols into corresponding uronic acids was demonstrated using 1-chloro-1,2-benziodoxol-3(1H)-one and TEMPO. The reaction proceeds at room temperature in good to excellent yields. Primary alcohols get oxidized selectively over the secondary alcohols under mild reaction conditions.     

A metal-free,hypervalent iodine(III)-induced tandem oxidative cycloisomerization based process for preparation of fluorescent diethyl 5,5′-diaryl-2,2′-bifuran-4,4′-dicarboxylates

A new method has been developed for concise synthesis of diethyl 5,5′-diaryl-2,2′-bifuran-4,4′-dicarboxylates. The preparative pathway begins with bis-C-alkylation reaction of the β-ketoester and 1,4-dibromobut-2-yne followed by hypervalent iodine (III)-mediated oxidative cycloisomerization reaction of the formed symmetric γ-alkynyl-diketones. The novel diethyl 5,5′-diaryl-2,2′-bifuran-4,4′-dicarboxylates, formed by using this process were found to possess unique fluorescence properties.     

Hypervalent Iodine‐Catalyzed Oxidative Functionalizations Including Stereoselective Reactions

Hypervalent iodine chemistry is now a well‐established area of organic chemistry. Novel hypervalent iodine reagents have been introduced in many different transformations owing to their mild reaction conditions and environmentally friendly nature. Recently, these reagents have received particular attention because of their applications in catalysis. Numerous hypervalent iodine‐catalyzed oxidative functionalizations such as oxidations of various alcohols and phenols, α‐functionalizations of carbonyl compounds, cyclizations, and rearrangements have been developed successfully. In these catalytic reactions stoichiometric oxidants such as mCPBA or oxone play a crucial role to generate the iodine(III) or iodine(V) species in situ. In this Focus Review, recent developments of hypervalent iodine‐catalyzed reactions are described including some asymmetric variants. Catalytic reactions using recyclable hypervalent iodine catalysts are also covered.     

Vicinal Difunctionalization of Alkenes with Iodine(III) Reagents and Catalysts

Hypervalent iodine(III) reagents have been known for over a century, and their reaction profile is still actively investigated. Recent years have seen impressive improvements in the area of alkene difunctionalization reactions, where new methodologies have become available. Especially chiral non‐racemic hypervalent iodine(III) reagents and catalysts have emerged as versatile tools for the realization of important enantioselective transformations.     

PhI(OAc)2‐Mediated Radical Trifluoromethylation of Vinyl Azides with Me3SiCF3

The fluorine‐containing organic motif is becoming privileged in pharmaceuticals, agrochemicals, and functional materials, owing to its unique properties such as electron‐withdrawing character, metabolic stability, and lipophilicity. Described herein is the PhI(OAc)₂‐mediated radical trifluoromethylation of vinyl azides with Me₃SiCF₃ to efficiently generate α‐trifluoromethyl azines. The resulting α‐trifluoromethyl azines were successfully transformed to valuable fluorine‐containing molecules such as α‐trifluoromethyl ketones, β‐trifluoromethyl amines, 5‐fluoropyrazoles, and trifluoroethyl isoquinolines.     

Rhodium‐Catalyzed CH Alkynylation of Arenes at Room Temperature

The rhodium(III)‐catalyzed ortho C? H alkynylation of non‐electronically activated arenes is disclosed. This process features a straightforward and highly effective protocol for the synthesis of functionalized alkynes and represents the first example of merging a hypervalent iodine reagent with rhodium(III) catalysis. Notably, this reaction proceeds at room temperature, tolerates a variety of functional groups, and more importantly, exhibits high selectivity for monoalkynylation.     

Metal‐Free Annulation of Arenes with 2‐Aminopyridine Derivatives: The Methyl Group as a Traceless Non‐Chelating Directing Group

A novel annulation reaction between 2‐aminopyridine derivatives and arenes under metal‐free conditions is described. The presented intermolecular transformation provided straightforward access to the important pyrido[1,2‐a]benzimidazole scaffold under mild reaction conditions. The unprecedented application of the methyl group of methylbenzenes as a traceless, non‐chelating, and highly regioselective directing group is reported.     

Anwendungen der Ringofenmethode auf radiochemische Probleme

Nach einer kurzen Einführung in die Ringofenmethode werden die Anwendungsmöglichkeiten dieser mikrochemischen Arbeitstechnik auf radiochemische Tennungen an einigen Beispielen erläutert. Hierbei handelt es sich um schnelle “Mutter-Tochter”-Trennungen (¹³⁷Cs/^137mBa;⁹⁹Mo/^99mTc) auf Rundfiltern, welche mit anorganischen Ionenaustauschern imprägniert sind, sowie um einen Trennungsgang für Uranspaltprodukte mittlerer bis langer Halbwertzeit.     

On Labelling with Generator Nuclides

Short-lived radioisotopes separated from radionuclide generators are widely used. In the paper possibilities of labelling with the daughter nuclides of the commercially available Mo/Tc-, Sn/In- and Te/I-generators and of the self-made Ba/La-generator in industrial tracer experiments are presented. The transfer of the daughter nuclides from the generator eluates into organic phases and the labelling of oil-phases and solid particles are investigated. The developed simple, quick and efficient methods are suitable for routine application under industrial conditions. Some examples of industrial applications of the generator nuclides are given, too.