Palladium-Catalyzed Decarbonylative Coupling of (Hetero)Aryl Boronate Esters with Difluorobenzyl Glutarimides

This report describes the Pd-catalyzed decarbonylative coupling of difluorobenzyl glutarimides with (hetero)aryl boronate esters to yield difluorobenzyl-substituted (hetero)arene products. The use of PAd2Bu as the phosphine ligand in combination with neopentylboronate ester nucleophiles proved critical for the selective formation of the decarbonylative coupling product versus analogous difluorobenzyl ketone. This transformation is effective for electronically diverse (hetero)aryl boronate esters and substituted difluorobenzyl glutarimides.

Palladium-Catalyzed Aryldifluoromethylation of Aryl Halides with Aryldifluoromethyl Trimethylsilanes

Diaryl difluoromethanes are valuable targets for medicinal chemistry because they are bioisosteres of diaryl ethers and can function as replacements for diaryl methane, ketone, and sulfone groups. However, methods to prepare diaryl difluoromethanes are scarce, especially methods starting from abundant aryl halides. We report the Pd-catalyzed aryldifluoromethylation of aryl halides with aryldifluoromethyl trimethylsilanes (TMSCF2 Ar). The reaction occurs when the catalyst contains a simple, but unusual, dialkylaryl phosphine ligand that promotes transmetallation of the silane. Computational studies show that reductive elimination following transmetallation occurs with a low barrier, despite the fluorine atoms on the α-carbon, due to coordination of the difluorobenzyl π-system to palladium. The co-development of a cobalt-catalyzed synthesis of the silanes broadened the scope of the process including several applications to the synthesis biologically relevant diaryl difluoromethanes.

Visible-Light-Induced Tandem Difluoroalkylated Spirocyclization of N-Arylpropiolamides: Access to C3-Difluoroacetylated Spiro[4,5]trienones

A visible-light-catalyzed difluoroacetylated spirocyclization of N-arylpropiolamides with ethyl bromodifluoroacetate as a CF2CO2Et radical precursor is described. This approach allows the formation of two carbon-carbon bonds and one carbon-oxygen bond in...

Stereoselective synthesis of fluoroalkylated (Z)-alkene via nickel-catalyzed and iron-mediated hydrofluoroalkylation of alkynes

An efficient nickel-catalyzed, iron-mediated hydrofluoroalkylation of alkynes with bromodifluoroacetate or perfluoroalkyl iodide, which proceeded smoothly to give fluoroalkylated (Z)-alkenes with high stereocontrol (up to 99 : 1 Z/E), was developed.

Ag-Catalyzed minisci C–H difluoromethylarylation of N-heteroarenes

A mild silver-catalyzed decarboxylative C–H difluoromethylarylation of electron-deficient N-heteroarenes.

PdII-Catalyzed methoxylation of C(sp3)-H bonds adjacent to benzoxazoles and benzothiazoles

The Pd(OAc)2/PhI(OAc)2 catalyst system promotes the highly regioselective dehydrogenative methoxylation of a C(sp3)-H bond adjacent to benzoxazole and benzothiazole rings. The title transformation constitutes the first example of a Pd-catalyzed C(sp3)-H activating methoxylation at the proximal-selective α-position with regard to a directing auxiliary and provides expedient access to an important class of azole-decorated methyl ethers (up to 90% isolated yield). The synthetic practicality of the methodology was demonstrated by achieving α-methoxyacetic acids via the elimination of the benzoxazole auxiliaries and by obtaining the precursor of an O-methylated Breslow intermediate.

Pd(ii)-Catalyzed decarboxylative meta-C–H difluoromethylation

Palladium(ii)-catalyzed decarboxylative meta-C–H difluoromethylation reactions have been developed. Initial mechanistic studies disclosed that a migratory insertion would be involved in this meta-selective C–H functionalization.

Copper-catalyzed difluoromethylation of propargylamide-substituted indoles: synthesis of mono- and bis-difluoromethylated indoloazepinone derivatives

A novel copper-catalyzed difluoromethylation of 2- or 3-propargylamide-substituted indoles with ICF2CO2Et via a radical cascade cyclization process is described. A wide substrate scope is compatible with the reaction conditions to synthesize mono- and bis-difluoromethylated indoloazepinone derivatives, which contain a seven-membered ring.

Nickel-catalyzed direct difluoromethylation of aryl boronic acids with BrCF2H

Nickel-catalyzed direct difluoromethylation of aryl boronic acids has been developed with the industrial raw material BrCF₂H.

A photoinduced reaction of perfluoroalkyl halides with 1,3-diarylprop-2-yn-1-ones catalyzed by DABSO

The sulfur dioxide surrogate of DABCO·(SO₂)₂ is used as an efficient catalyst for the cleavage of the perfluoroalkyl-halogen bond under visible-light irradiation. A plausible mechanism supported by theoretical calculations is proposed.

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.

Silver-catalyzed oxidative decarboxylation of difluoroacetates: efficient access to C–CF2 bond formation

Ag(i)-catalyzed oxidative decarboxylative gem-difluoromethylenation of difluoroacetates with isonitriles has been developed for the formation of C–CF₂ bonds.

Copper-mediated aerobic (phenylsulfonyl)difluoromethylation of arylboronic acids with difluoromethyl phenyl sulfone

The “PhSO₂CF₂Cu” reagent (from PhSO₂CF₂H) reacts with arylboronic acids, which represents a convenient method for the introduction of the CF₂ moiety into aromatics.

Visible-light-mediated radical aryldifluoroacetylation of alkynes with ethyl bromodifluoroacetate for the synthesis of 3-difluoroacetylated coumarins

A mild and efficient method for the synthesis of 3-difluoroacetylated coumarins through visible-light-promoted aryldifluoroacetylation of alkynes with ethyl bromodifluoroacetate has been developed. The reaction allows the direct formation of Csp(2)-CF2COOEt and C-C bonds via a proposed tandem radical cyclization process.

An efficient regioselective hydrodifluoromethylation of unactivated alkenes with TMSCF2CO2Et at ambient temperature

An efficient regioselective hydrodifluoromethylation of diverse unactivated vicinal alkenes is described. The primary mechanistic investigations indicate that a CF₂COOEt radical species is involved.