Visible-Light-Promoted bis(Difluoromethylation)/Cyclization of 2-Vinyloxy Arylalkynes to Prepare Benzofuran Derivatives

A visible-light-promoted difluoromethylation/cyclization of 2-vinyloxy arylalkynes was developed, providing a variety of bis(difluoromethyl)-substituted benzofurans in moderate to good yields. A plausible mechanism involving difluoromethyl radical cascade cyclization and solvent-promoted ionic addition was proposed. This protocol has the advantages of having mild reaction conditions, simple operation, and good functional group tolerance.

Organic semiconductor photocatalyst can bifunctionalize arenes and heteroarenes

Photoexcited electron-hole pairs on a semiconductor surface can engage in redox reactions with two different substrates. Similar to conventional electrosynthesis, the primary redox intermediates afford only separate oxidized and reduced products or, more rarely, combine to one addition product. Here, we report that a stable organic semiconductor material, mesoporous graphitic carbon nitride (mpg-CN), can act as a visible-light photoredox catalyst to orchestrate oxidative and reductive interfacial electron transfers to two different substrates in a two- or three-component system for direct twofold carbon-hydrogen functionalization of arenes and heteroarenes. The mpg-CN catalyst tolerates reactive radicals and strong nucleophiles, is straightforwardly recoverable by simple centrifugation of reaction mixtures, and is reusable for at least four catalytic transformations with conserved activity.

Visible-Light-Induced para-Selective C(sp2)-H Difluoroalkylation of Diverse (Hetero)aromatic Carbonyls

An efficient visible-light-induced para-selective C(sp²)-H difluoroalkylation of diverse electron-deficient (hetero)aromatic carbonyls (aldehydes and ketones) at ambient temperature has been developed by employing Ir(ppy)₃ as the catalyst and 1,10-phenanthroline as the additive. This protocol was highlighted by its wide substrate scope, high regioselectivity, low catalyst usage, and operational simplicity.

Catalyst-Free, Direct Electrochemical Tri- and Difluoroalkylation/Cyclization: Access to Functionalized Oxindoles and Quinolinones

The catalyst-free electrochemical di- and trifluoromethylation/cyclization of N-substituted acrylamides was realized under external oxidant-free conditions. The strategy provides expedient access to fluoroalkylated oxindoles and 3,4-dihydroquinolin-2(1 H)-ones with ample scope and broad functional group tolerance by mild, direct electrolysis of sodium sulfinates in an undivided cell. Detailed mechanistic studies provided strong support for a SET-based reaction manifold.

Copper-Promoted Cross-Coupling Reactions for the Synthesis of Aryl(difluoromethyl)phosphonates Using Trimethylsilyl(difluoromethyl)phosphonate

A convenient and effective route for the synthesis of aryl(difluoromethyl)phosphonates has been developed based on cross-coupling reactions. Upon treatment with a stoichiometric amount (or a catalytic amount in some cases) of CuI and CsF, aryl iodides reacted smoothly with (silyldifluoromethyl)phosphonates to give the corresponding aryl(difluoromethyl)phosphonates in good yields.

Visible-light-promoted organic-dye-catalyzed three-component coupling of aldehydes, hydrazines and bromodifluorinated reagents

α,α-Difluoroketone hydrazones have been synthesised from readily available aldehydes, hydrazines, and bromodifluorinated reagents via visible-light photoredox catalysis.

Palladium-Catalyzed Cross-Coupling of Ethyl Bromodifluoroacetate with Aryl Bromides or Triflates and Cross-Coupling of Ethyl Bromofluoroacetate with Aryl Iodides

A palladium-catalyzed Negishi cross-coupling reaction of ethyl bromodifluoroacetate with aryl bromides or aryl triflates to construct C(sp²)-CF₂ bonds is described. The reaction was conducted under mild reaction conditions, and no preparation of organozinc reagents is required. This is the first report encompassing the conversion of aryl triflates into products containing C-CF₂ bonds. In addition, the construction of C(sp²)-CHF bonds was achieved under mild conditions via a cross-coupling of aryl iodides with ethyl bromofluoroacetate.

Stereoselective access to trisubstituted fluorinated alkenyl thioethers

We report the first copper-catalyzed olefinic ethoxy carbonyl difluoromethylation of alkenyl thioethers via direct C–H bond functionalization using BrCF₂COOEt.

Ag(i)-Catalyzed oxidative decarboxylation of difluoroacetates with activated alkenes to form difluorooxindoles

A silver-catalyzed oxidative decarboxylative gem-difluoromethylenation of difluoroacetates with activated alkenes to gem-difluoromethylenated oxindoles.

CuBr-mediated radical cascade difluoroacetamidation of acrylamides using α,α-difluoro-α-(TMS)-acetamides

Radical cascade difluoroacetamidation of N-(arylsulfonyl)acrylamides with α,α-difluoro-α-(TMS)-acetamides has been achieved for the first time.