Iron-Catalyzed Regio- and Stereoselective Chlorosulfonylation of Terminal Alkynes with Aromatic Sulfonyl Chlorides

Terminal alkynes react with aromatic sulfonyl chlorides in the presence of an iron(II) catalyst and a phosphine ligand to give (<i>E</i>)-β-chlorovinylsulfones with 100% regio- and stereoselectivity. Various functional groups, such as chloride, bromide, iodide, nitro, ketone, and aldehyde, are tolerated under the reaction conditions. Addition of tosyl chloride to a 1,6-enyne followed by radical 5-<i>exo</i>-<i>trig</i> cyclization gave an exocyclic alkenylsulfone

Nickel-Catalyzed Synthesis of Diarylamines via Oxidatively Induced C–N Bond Formation at Room Temperature

A nickel-catalyzed oxidative coupling of zinc amides with organomagnesium compounds selectively produces diarylamines under mild reaction conditions, with tolerance for chloride, bromide, hydroxyl, ester, and ketone groups. A diamine is bis-monoarylated. A bromoaniline undergoes <i>N</i>-arylation followed by Kumada–Tamao–Corriu coupling in one pot. The reaction may proceed via oxidatively induced reductive elimination of a nickel species

Iron-Catalyzed Directed C(sp²)–H and C(sp³)–H Functionalization with Trimethylaluminum

Conversion of a C­(sp²)–H or C­(sp³)–H bond to the corresponding C–Me bond can be achieved by using AlMe₃ or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron­(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)­aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500

Iron-Catalyzed <i>Ortho</i> C–H Methylation of Aromatics Bearing a Simple Carbonyl Group with Methylaluminum and Tridentate Phosphine Ligand

Iron-catalyzed C–H functionalization of aromatics has attracted widespread attention from chemists in recent years, while the requirement of an elaborate directing group on the substrate has so far hampered the use of simple aromatic carbonyl compounds such as benzoic acid and ketones, much reducing its synthetic utility. We describe here a combination of a mildly reactive methylaluminum reagent and a new tridentate phosphine ligand for metal catalysis, 4-(bis­(2-(diphenyl­phosphanyl)­phenyl)­phosphanyl)-<i>N</i>,<i>N</i>-dimethyl­aniline (Me₂N-TP), that allows us to convert an <i>ortho</i> C–H bond to a C–CH₃ bond in aromatics and heteroaromatics bearing simple carbonyl groups under mild oxidative conditions. The reaction is powerful enough to methylate all four <i>ortho</i> C–H bonds in benzophenone. The reaction tolerates a variety of functional groups, such as boronic ester, halide, sulfide, heterocycles, and enolizable ketones

Iron-Catalyzed Chemo- and Stereoselective Hydromagnesiation of Diarylalkynes and Diynes

Diarylalkynes are chemo- and stereoselectively hydromagnesiated in high yields at room temperature with an iron species generated in situ from FeCl₂ and EtMgBr. Functional groups such as bromide, iodide, amine, phenoxide, and alkene are well tolerated. Under similar conditions, diynes are chemo-, regio-, and stereoselectively hydromagnesiated. The resulting alkenylmagnesium compounds are a platform for further functionalization as a one-pot reaction

Iron-Catalyzed Directed C(sp²)–H and C(sp³)–H Functionalization with Trimethylaluminum

Conversion of a C­(sp²)–H or C­(sp³)–H bond to the corresponding C–Me bond can be achieved by using AlMe₃ or its air-stable diamine complex in the presence of catalytic amounts of an inorganic iron­(III) salt and a diphosphine along with 2,3-dichlorobutane as a stoichiometric oxidant. The reaction is applicable to a variety of amide substrates bearing a picolinoyl or 8-aminoquinolyl directing group, enabling methylation of a variety of (hetero)­aryl, alkenyl, and alkyl amides. The use of the mild aluminum reagent prevents undesired reduction of iron and allows the reaction to proceed with catalyst turnover numbers as high as 6500

Silylation of Aryl Halides with Monoorganosilanes Activated by Lithium Alkoxide

Lithium alkoxide activates a monoorganosilane to generate a transient LiH/alkoxysilane complex, which quickly reacts with aryl and alkenyl halides at 25 °C to deliver a diorganosilane product. Experimental and theoretical studies suggest that the reaction includes nucleophilic attack of LiH on the halogen atom of the organic halide to generate a transient organolithium/alkoxysilane intermediate, which undergoes quick carbon–silicon bond formation within the complex

Iron-Catalyzed <i>Ortho</i>-Allylation of Aromatic Carboxamides with Allyl Ethers

Arenes possessing an <i>N</i>-(quinolin-8-yl)­amide directing group are <i>ortho</i>-allylated with allyl phenyl ether in the presence of an iron/diphosphine catalyst and an organometallic base at 50–70 °C. The reaction proceeds via fast iron-catalyzed C–H activation, followed by reaction of the resulting iron intermediate with the allyl ether in γ-selective fashion

Nickel-Catalyzed Monosubstitution of Polyfluoroarenes with Organozinc Reagents Using Alkoxydiphosphine Ligand

A new diphosphine (POP) ligand bearing an alkoxide group allows us to synthesize partially fluorinated arenes. A nickel-catalyzed cross-coupling between a polyfluoroarene and an organozinc reagent in the presence of POP selectively produces a monosubstitution product. Aryl and alkylzinc reagents smoothly take part in the reaction. It is speculated that monosubstitution is the result of accelerated product expulsion from the product/catalyst complex