Search

N‐heterocyclic carbenes (NHCs) have emerged as catalysts for the construction of C−C bonds in the synthesis of substituted ketones under single‐electron processes. Despite these recent reports, there still remains a need to increase the utility and practicality of these reactions by exploring new radical coupling partners. Herein, we report the synthesis of γ‐aryloxyketones via combined NHC/photoredox catalysis. In this reaction, an α‐aryloxymethyl radical is generated via oxidation of an aryloxymethyl potassium trifluoroborate salt, which is then added into styrene derivatives to provide a stabilized benzylic radical. Subsequent radical‐radical coupling reaction with an azolium radical affords the γ‐aryloxy ketone products. [ABSTRACT FROM AUTHOR]

As a key element in the construction of complex organic scaffolds, the formation of C−C bonds remains a challenge in the field of synthetic organic chemistry. Recent advancements in single‐electron chemistry have enabled new methods for the formation of various C−C bonds. Disclosed herein is the development of a novel single‐electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium in situ followed by a radical–radical coupling was made possible merging N‐heterocyclic carbene (NHC) and photoredox catalysis. The utility of this protocol in synthesis was showcased in the late‐stage functionalization of a variety of pharmaceutical compounds. Preliminary investigations using chiral NHCs demonstrate that enantioselectivity can be achieved, showcasing the advantages of this protocol over alternative methodologies. [ABSTRACT FROM AUTHOR]

As a key element in the construction of complex organic scaffolds, the formation of C-C bonds remains a challenge in the field of synthetic organic chemistry. Recent advancements in single-electron chemistry have enabled new methods for the formation of various C-C bonds. Disclosed herein is the development of a novel single-electron reduction of acyl azoliums for the formation of ketones from carboxylic acids. Facile construction of the acyl azolium in situ followed by a radical-radical coupling was made possible merging N-heterocyclic carbene (NHC) and photoredox catalysis. The utility of this protocol in synthesis was showcased in the late-stage functionalization of a variety of pharmaceutical compounds. Preliminary investigations using chiral NHCs demonstrate that enantioselectivity can be achieved, showcasing the advantages of this protocol over alternative methodologies., (© 2020 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

A method for the synthesis of iodinated imidazolium and triazolium N-heterocyclic halogen-bond-donor catalysts has been developed. This approach was applied to the synthesis of a variety of 1,2,4-triazolium salts to prepare a series of novel chiral halogen-bond-donor catalysts. The counterions of the iodinated triazoliums can be readily exchanged with chiral and achiral non-coordinating counterions to produce unique scaffolds. Their ability to promote/catalyse a conjugate addition reaction with indole was investigated. Through these initial studies, a set of general guidelines and considerations for the application of these halogen-bond donors in organocatalysis have been established., (© 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The synthesis of densely functionalized N-heterocycles is an ongoing challenge in chemical synthesis. Herein, we report an efficient method for the construction of pyrrolidine and piperidine scaffolds using a palladium-catalyzed carboamination of alkylidenecyclopropanes., (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.)