A visible-light-engaged 2-fold site-selective alkylation of indole derivatives with aliphatic ethers or alcohols has been accomplished for easy access to symmetric 3,3′-bisindolylmethane derivatives. The experimental data suggest a sequential photoredox catalysis induced radical addition and proton-mediated Friedel–Crafts alkylation mechanism.

An efficient synthesis of (3-isoindazolyl)allenes from 2-alkynyl azobenzenes and terminal alkynes via cooperative Pd(PPh3)2Cl2/CuI-catalyzed cross-coupling has been developed. By making use of this approach, (3-isoindazolyl)allenes with various substituents can be synthesized in good to excellent yields. A rapid synthesis of biologically active indazolo[2,3-a]quinoline was also achieved using this method as the key step.

The manganese-catalyzed α-fluoroalkenylation of arenes via C–H activation and C–F cleavage has been described. This protocol provides a very useful method for the synthesis of monofluoroalkenes with predominant unconventional E-isomer selectivity which complements the existing strategies for the access to these molecular architectures. In addition, the selectivity of β-defluorination in the catalytic cycle not only determines the configurations of the products but also obviates the use of external oxidants, providing a good example in the exploitation of manganese-catalyzed redox-neutral C–H transformations.

An unprecedented Rh-catalyzed C2-difluoroalkylation of indole derivatives with 2,2-difluorovinyl arenesulfonates has been reported. This reaction provides a rare instance of catalytic difluoroalkylation through hydroarylation of gem-difluoroalkenes. The sulfonate group works as a chelating ligand, thus stabilizing the rhodacycle intermediate, leading to the uncommon transformation.

AbstractAn unprecedented rhodium(III)-catalyzed hydroarylation of α,α-difluoromethylene alkynes with N-pivaloxyl aroylamides through sequential C−H activation and aryl migration is detailed herein. A large array of α,α-difluoromethylene alkynes and N-pivaloxyl aryl amides were amenable to this transformation, thus providing a novel synthetic protocol for the construction of difluorinated 2-alkenyl aniline derivatives in high yields and with excellent regioselectivity. Notably, unique fluorine effects were found to underlie the thus unconventional reaction manifold.

AbstractA Pd-catalyzed fluoroarylation of gem-difluoroalkenes with aryl halides is reported. By taking advantage of the in situ generated α-CF3-benzylsilver intermediates derived from the nucleophilic addition of silver fluoride to gem-difluoroalkenes, this strategy bypasses the use of a strong base, thus enabling a mild and general synthetic method for ready access to non-symmetric α,α-disubstituted trifluoroethane derivatives.

AbstractA Pd-catalyzed fluoroarylation of gem-difluoroalkenes with aryl halides is reported. By taking advantage of the in situ generated α-CF3-benzylsilver intermediates derived from the nucleophilic addition of silver fluoride to gem-difluoroalkenes, this strategy bypasses the use of a strong base, thus enabling a mild and general synthetic method for ready access to non-symmetric α,α-disubstituted trifluoroethane derivatives.

AbstractAn unprecedented rhodium(III)-catalyzed hydroarylation of α,α-difluoromethylene alkynes with N-pivaloxyl aroylamides through sequential C−H activation and aryl migration is detailed herein. A large array of α,α-difluoromethylene alkynes and N-pivaloxyl aryl amides were amenable to this transformation, thus providing a novel synthetic protocol for the construction of difluorinated 2-alkenyl aniline derivatives in high yields and with excellent regioselectivity. Notably, unique fluorine effects were found to underlie the thus unconventional reaction manifold.

Herein we present a novel strategy based on palladium-catalyzed allylic alkylation by taking advantage of the nucleophilic addition of external fluoride onto gem-difluoroalkenes as the initiation step. The merit of this protocol is highly appealing, as it enables a formal allylation of trifluoroethylarene derivatives through the in situ generation of β-trifluorocarbanions, which otherwise are deemed to be problematic in deprotonative allylation. Furthermore, this strategy distinguishes itself by high modularity, operational simplicity, and wide substrate scope with respect to allyl carbonates, giving rise to a broad array of homoallyltrifluoromethane derivatives, which otherwise would not be easily obtained using existing synthetic methods.

An efficient strategy which integrates visible-light-induced iminyl-radical formation with carboimination of unactivated alkenes has been developed for the easy access of densely functionalized pyrroline derivatives. With fac-[Ir(ppy)3] as photoredox catalyst, the acyl oximes were converted into iminyl radical intermediates by one electron reduction, and evolve through a cascade of intramolecular cyclization and intermolecular carbon radical trapping to give the functionalized pyrrolines. The utilization of silyl enol ethers as coupling partners not only allows the introduction of synthetically useful ketone functionalities but also renders catalyst regeneration without any external reductants. This protocol is characterized by its mild reaction conditions and the tolerance of a broad range of functionalities.Keywords: iminyl radicals; N-heterocycles; photoredox catalysis; pyrroline; visible light

A Cu(I)-catalyzed direct intermolecular oxyamination of electron deficient alkenes is disclosed. This process is characterized by difunctionalization of a variety of α,β-unsaturated ketones with easily available N-acyloxyamine reagents as both amine and oxygen donors, which delivers ester derivatives of β-amino alcohols in good yields as well as with high regioselectivity. Control studies suggested the involvement of alkyl radical species on the way of product formation.

An efficient synthesis of (3-isoindazolyl)allenes from 2-alkynyl azobenzenes and terminal alkynes via cooperative Pd(PPh3)2Cl2/CuI-catalyzed cross-coupling has been developed. By making use of this approach, (3-isoindazolyl)allenes with various substituents can be synthesized in good to excellent yields. A rapid synthesis of biologically active indazolo[2,3-a]quinoline was also achieved using this method as the key step.

A Cu(I)-catalyzed direct intermolecular oxyamination of electron deficient alkenes is disclosed. This process is characterized by difunctionalization of a variety of α,β-unsaturated ketones with easily available N-acyloxyamine reagents as both amine and oxygen donors, which delivers ester derivatives of β-amino alcohols in good yields as well as with high regioselectivity. Control studies suggested the involvement of alkyl radical species on the way of product formation.

The manganese-catalyzed α-fluoroalkenylation of arenes via C–H activation and C–F cleavage has been described. This protocol provides a very useful method for the synthesis of monofluoroalkenes with predominant unconventional E-isomer selectivity which complements the existing strategies for the access to these molecular architectures. In addition, the selectivity of β-defluorination in the catalytic cycle not only determines the configurations of the products but also obviates the use of external oxidants, providing a good example in the exploitation of manganese-catalyzed redox-neutral C–H transformations.