Showcasing the concept of light-induced homo¬lysis for the generation of radicals, the CuII-photocatalyzed decarboxylative oxygenation of carboxylic acids with molecular oxygen as the terminal oxidant is described. Two CuII-carboxylate complexes...

We report the visible light-mediated coppercatalyzed vicinal difunctionalization of olefins utilizing bromonitroalkanes as ATRA reagents. This protocol is characterized by high yields and fast reaction times under environmentally benign reaction conditions with exceptional scope, allowing the rapid functionalization of both activated and unactivated olefins. Moreover, late-stage functionnalization of biologically active molecules and upscaling to gram quantities is demonstrated, which offers manifold possibilities for further transformations, e.g. access to nitro-and aminocyclopropanes. Besides the synthetic utility of the title transformation, this study undergirds the exclusive role of copper in photoredox catalysis showing its ability to stabilize and interact with radical intermediates in its coordination sphere. EPR studies suggest that such interactions can even outperform a highly favorable cyclization of transient to persistent radicals contrasting iridium-based photocatalysts.

Motivated by the medical interest in methylene blue as potential anti-Alzheimer agent, the charge densities of three salt structures containing the methylene blue cation with nitrate (as dihydrate), chloride (as pentahydrate) and thiocyanate counter-ions were generated by application of the invariom formalism and examined. The so-obtained charge density distributions were analyzed using the QTAIM formalism to yield bond topological and atomic properties. The atomic charges on the methylene blue cation indicate a delocalized charge distribution; only a small positive charge on the sulfur atom was found. Electrostatic potentials mapped onto iso-surfaces of electron density for the cations, and for the methylene blue cations with anions, were compared. The effect of hydrogen disorder on the molecular electrostatic potential was investigated for the thiocyanate structure.

Wir berichten eine durch sichtbares Licht kupferkatalysierte vicinale Difunktionalisierung von Olefinen unter Verwendung von Bromnitroalkanen als ATRA-Reagenzien. Dieses Protokoll zeichnet sich durch hohe Ausbeuten und schnelle Reaktionszeiten unter umweltfreundlichen Reaktionsbedingungen mit außergewöhnlich breitem Substratspektrum aus. Darüber ist die Funktionalisierung biologisch aktiver Moleküle und das Skalieren auf Grammmengen möglich, was vielfältige Möglichkeiten für weitere Transformationen bietet, z. B. den Zugang zu Nitro-und Aminocyclopropanen. Neben dem synthetischen Nutzen der Reaktion untermauert diese Studie die exklusive Rolle von Kupfer in der Photoredoxkatalyse und zeigt dessen Fähigkeit, radikalische Zwischenstufen in seiner Koordinationssphäre zu stabilisieren und mit ihnen zu interagieren. EPR-Studien deuten darauf hin, dass solche Wechselwirkungen im Gegensatz zu Iridium-basierten Photokatalysatoren sogar eine sehr günstige Zyklisierung von transienten zu persistenten Radikalen übertreffen können.

Due to their high stability towards enzymatic hydrolysis C‐acyl glycosidic compounds are useful synthetic intermediates for potential candidates in drug discovery. Syntheses for C‐acyl mannosides have remained scarce and usually employ donors obtained from lengthy syntheses. Furthermore, syntheses of unprotected C‐acyl mannosides have not been reported so far, due to the incapability of the C‐acyl mannoside motif with deprotection conditions for protective groups commonly used in carbohydrate chemistry. Herein, we report an efficient and highly α‐selective four‐step one‐pot method for the synthesis of C‐acyl α‐d‐manno‐, l‐rhamno‐ and d‐lyxopyranosides from easily accessible persilylated monosaccharides and dithianes requiring only trace amounts of a copper source as catalyst and explain the crucial role of the catalyst by mechanistic studies. Furthermore, the C‐acyl α‐glycosides were easily isomerized to give rapid access to their β‐anomers.