Copper-Catalyzed Oxydifluoroalkylation of Hydroxyl-Containing Alkenes

Base-Dependent Divergent Carbodifluoroalkylation and Halodifluoroalkylation of Alkenes under Visible-Light Irradiation

Organic molecules containing a difluoroalkyl group are valuable and versatile chemicals because of their unique physicochemical and biological properties. Accordingly, the development of efficient and practical difluoroalkylation for the preparation of these compounds is important and attractive. Herein, we demonstrate photoredox-catalyzed and base-dependent selective carbodifluoroalkylation and halodifluoroalkylation of alkenes using readily available 2-(allyloxy)arylaldehydes [or 2-(allylamino)arylaldehydes] and XCF2COOEt (or BrCF2CONR1R2) as starting materials. The developed reaction enables convenient and accurate synthesis of difluoroalkylated chroman-4-ones and aldehydes and features broad substrate scope, mild conditions, and operational simplicity. Moreover, gram-scale product preparation and application of the title protocol in late-stage functionalization of pharmaceutical molecules are accomplished.

Cobalt-catalyzed decarboxylative difluoroalkylation of nitrophenylacetic acid salts

The selective installation of fluorine-containing groups into biologically relevant molecules has been used as a common strategy for the development of pharmaceutically active molecules. However, the selective incorporation of gem-difluoromethylene groups next to sterically demanding secondary and tertiary alkyl groups remains a challenge. Herein, we report the first cobalt-catalyzed regioselective difluoroalkylation of carboxylic acid salts. The reaction allows for the facile construction of various difluoroalkylated products in good yields tolerating a wide range of functionalities on either reaction partner. The potential of the method is illustrated by the late-stage functionalization of molecules of biological relevance. Mechanistic studies support the in situ formation of a cobalt(i) species and the intermediacy of difluoroalkyl radicals, thus suggesting a Co(i)/Co(ii)/Co(iii) catalytic cycle.

Copper-Catalyzed Difluoroalkylation Reaction

This review describes recent advances in copper-catalyzed difluoroalkylation reactions. The RCF₂ radical is generally proposed in the mechanism of these reactions. At present, various types of copper-catalyzed difluoroalkylation reactions have been realized. According to their characteristics, we classify these difluoroalkylation reactions into three types.

Tetrahydroxydiboron and Nickel Chloride Cocatalyzed Rapid Radical Cyclization toward Pyrrolizidine and Indolizidine Alkaloids

A novel tetrahydroxydiboron and nickel chloride cocatalyzed radical cyclization cascade with a broad substrate scope and an ultrashort reaction time was developed. The mechanistic investigation indicated that the reaction might involve a homocleavage of tetrahydroxydiboron and nickel hydride intermediates. This approach enables the simple and efficient synthesis of a series of heteropolycycles.

Metal-Free Difunctionalization of Pyridines: Selective Construction of N-CF2H and N-CHO Dihydropyridines

The reactivity of N-difluoromethylpyridinium salts is seldom explored because of their instability and low availability. Here we present a novel nucleophilic addition of N-difluoromethylpyridinium salts with nitroalkanes to synthesize N-CF₂H-dihydropyridines and N-CHO-dihydropyridines in a highly efficient and regioselective pathway. This protocol exhibits good functional group tolerance and good to excellent yields.

Visible-Light-Induced, Catalyst-Free Radical Cross-Coupling Cyclization of N-Allylbromodifluoroacetamides with Disulfides or Diselenides

A visible-light-induced, catalyst-free radical cross-coupling cyclization of diselenides or disulfides with N-allylbromodifluoroacetamide has been developed. This developed protocol exhibits good functional group tolerance and affords a variety of 4-thio- and 4-seleno-substituted 3,3-difluoro-γ-lactams in moderate to good yields. Based on control experiments, a plausible radical-radical cross-coupling pathway is proposed.

Copper-catalyzed regioselective sulfonylcyanations of vinylarenes

A set of copper-catalyzed sulfonylcyanations of vinylarenes with readily accessible arylsulfonyl chlorides and trimethyl cyanide was achieved, providing a streamlined route to various decorated β-sulfonyl nitriles with good regioselectivity and functional group tolerance.

Promising reagents for difluoroalkylation

This review describes recent advances in difluoroalkylation reactions using different substrates.

Synthesis of difluoroalkylated 2-azaspiro[4.5]decane derivatives via copper-catalyzed difluoroalkylation/dearomatization of N-benzylacrylamides

A copper-catalyzed synthesis of difluoroalkylated spiro-azacycles from N-benzylacrylamides is presented. The reaction involves the β-difluoroalkylation of acrylamide, 5-exo cyclization, and dearomatization.

Copper/B2pin2-Catalyzed Difluoroalkylation of Methylenecyclopropanes with Bromodifluorinated Acetates and Acetamides: One-Pot Synthesis of CF2-Containing Dihydronaphthalene Derivatives

Novel copper/B₂pin₂-catalyzed difluoroalkylation of methylenecyclopropanes with bromodifluorinated acetates and acetamides via a tandem radical process involving ring-opening/intramolecular cyclization has been reported. This protocol is not only tolerated to a diverse range of substrates but also applicable to the synthesis of useful difluoromethylated compounds. Moreover, the reaction could be performed on a gram scale with a high yield, which opens up the possibility for practical applications.