Search

Oxidative N‐heterocyclic carbene (NHC) organocatalysis, typically leading to the formation of acyl azolium reactive intermediates, constitutes one of the most important activation strategies for the NHC‐catalyzed chemical transformations. Here, we report an unprecedented oxidative radical NHC catalysis by using peroxyester as the external single‐electron oxidant to realize divergent difunctionalization of olefins. The key to success of this chemistry is the catalytic generation of oxygen radicals that could trigger an intermolecular hydrogen atom transfer to activate the inert C−H bonds, thereby enabling the productive radical relay process. With this protocol, commonly used general chemicals could serve as radical precursors to allow efficient synthesis of value‐added products in a straightforward and cost‐effective manner. Preliminary mechanistic investigations, including control experiments and DFT calculations, shed light on the NHC organocatalytic radical reaction mechanism. [ABSTRACT FROM AUTHOR]

Fluorinated ketones are widely prevalent in numerous biologically interesting molecules, and the development of novel transformations to access these structures is an important task in organic synthesis. Herein, we report the multicomponent radical acylfluoroalkylation of a variety of olefins in the presence of various commercially available aromatic aldehydes and fluoroalkyl reagents through N‐heterocyclic carbene organocatalysis. With this protocol, over 120 examples of functionalized ketones with diverse fluorine substituents have been synthesized in up to 99 % yield with complete regioselectivity. The generality of this catalytic strategy was further highlighted by its successful application in the late‐stage functionalization of pharmaceutical skeletons. Excellent diastereoselectivity could be achieved in the reactions forging multiple stereocenters. In addition, preliminary results have been achieved on the catalytic asymmetric variant of the olefin difunctionalization process. [ABSTRACT FROM AUTHOR]

Innentitelbild: Radical Acylfluoroalkylation of Olefins through N-Heterocyclic Carbene Organocatalysis (Angew. B Die Mehrkomponenten-Acylfluoralkylierung b von Olefinen durch NHC-Organokatalyse (NHC=N-heterocyclisches Carben) wird im Forschungartikel von J.-L. Li, B. Han, Q.-Z. Die Allgemeingültigkeit der Methode wird durch die Modifizierung pharmazeutischer Gerüste in späten Synthesestadien unterstrichen. [Extracted from the article]