Cooperative Photoredox and N-Heterocyclic Carbene Catalysis Suzuki-Miyaura-Type Reaction: Radical Coupling of Aroyl Fluorides and Alkyl Boronic Acids.

An intermolecular Suzuki-Miyaura-type reaction of benzoyl fluorides with alkyl boronic acids to synthetic ketone was revealed by cooperative N-heterocyclic carbene (NHC) and photoredox catalysis. Various alkyl boric acids can be converted into alkyl radicals without external oxidants or activators. Moreover, the catalytic system was feasible for the difunctionalization of styrenes via a radical relay process. Mechanistic experiments suggested that the benzoate anion intermediate might play a unique role in this reaction system.

Synthesis of α-Trifluoromethyl Alkynes through Fluoroalkynylation of gem-Difluoroalkenes.

A trifluoromethylalkynylation reaction of gem-difluoroalkenes with alkynyl sulfoxide by photoredox radical addition with good functional group tolerance in moderate to high yields, is developed for the synthesis of α-trifluoromethyl alkyne. This reaction features simple operation and inexpensive raw materials and provides an expeditious route to synthesize biologically relevant fluorine-containing alkynyl compounds with diverse structural skeletons.

Phosphine-Promoted Tandem Intermolecular Diels-Alder Reactions with Pentadienyl 4-Nitrobenzoate as a Diene Precursor.

A phosphine-promoted tandem Diels-Alder reaction using pentadienyl 4-nitrobenzoate (α-vinyl MBH adduct) as a diene precursor with 3-olefinic oxindoles or CF3-activated ketones as dienophiles has been developed. The reaction proceeds through the formation of a pentadienyl phosphonium intermediate via SN2'' addition, which acts as both a D-A diene and a precursor for the exomethylene moiety. This method offers a metal-free and step-efficient approach for synthesizing exomethylene-bearing spirooxindoles and dihydropyrans, which are privileged structures found in natural products.

Ketone Synthesis via Irradiation-Induced Generation of a Persistent Ketyl Radical from Acyl Azolium Salts.

A novel three-component α-acylated difunctionalization of alkenes strategy has been developed on the basis of a direct hydrogen atom transfer (HAT) process of photoinduced acyl azolium salts. With simple irradiation without the catalyst, a variety of olefins can be directly converted into ketone derivatives, including 1,4-dione, ß-silyl ketone, 1,5-dione, etc. Mechanistic investigations indicated that the unique reactivity of the acyl azonium triplet excited state is crucial to the strategy's success.

Visible-Light-Mediated NHC and Tertiary Amine Catalysis Enabling α-H Acylation of Alkenes.

An intermolecular direct α-C-H acylation of alkenes was revealed by the visible-light-mediated N-heterocyclic carbene and quinuclidine catalysis. This convenient protocol provides a facile synthesis toward novel natural products and drug derivatives of α-substituted vinyl ketones. Mechanistic investigations indicated that the transformation proceeded via sequential radical addition, radical coupling, and an elimination process.

Copper-Catalyzed Monofluoroalkylation of Allyl Phosphates with Nucleophilic Ethyl 2-Fluoro-2-(trimethylsilyl)acetate.

An efficient method for C(sp3)-CHF bond formation was successfully developed by copper-catalyzed cross-coupling of allyl phosphate with 2-fluoro-2-(trimethylsilyl)acetate. Under moderate circumstances, the conversion was carried out in a good strategic range to provide a series of monofluoroalkylation products in high yields, which also demonstrates the practicality of gram-scale reactions.

3D Lanthanide Neodymium Porphyrin Metal-Organic Framework for Photocatalytic Oxidation of Styrene.

A novel three-dimensional lanthanide porphyrin-based MOF (Nd-PMOFs) was synthesized by using tetracarboxyphenyl porphyrin as the ligand and the lanthanide Nd as the coordination metal. Its specific crystal structure information was obtained by single-crystal diffraction with the space group C2/c and the empirical formula C72H45N6Nd2O15.25. This new Nd porphyrin-based MOF with an organic framework formed by a unique coordination method enables the effective separation of photogenerated electrons and holes under photoluminescence, giving it excellent photocatalytic property which could be verified by the characterization data. The photocatalytic performance was examined by taking tert-butyl hydroperoxide as the oxidant and Nd-PMOFs as the catalyst for photocatalytic oxidation of styrene to benzaldehyde with 91.4% conversion and 81.2% benzaldehyde selectivity under optimal reactions, which surpasses most of the results reported in the literature. Several styrenes with other substituents were screened to explore the general applicability of Nd-PMOF for photocatalysis of styrene, among which Nd-PMOFs also exhibited excellent photocatalytic performance. This work offers the possibility to apply lanthanide organometallic frameworks, which are widely used in fluorescent materials, to photocatalysis. In addition, it also provides a new method for the catalytic generation of benzaldehyde from styrene that is consistent with the needs of modern green development.

Chemoselective tandem SN2'/SN2''/inter- or intramolecular Diels-Alder reaction of γ-vinyl MBH carbonates with phenols and o-hydroxychalcones.

An unprecedented consecutive SN2'/SN2'' addition of phenol to γ-vinyl MBH carbonate forms a reactive diene intermediate, followed by a dimerization/elimination process to give functionalized exocyclohexenes with excellent chemoselectivity. When using o-hydroxychalcones as pronucleophiles, an SN2'/SN2''/intramolecular Diels-Alder reaction sequence occurs, selectively producing a series of pharmaceutically intriguing tricyclic chromane derivatives with good diastereoselectivity. The good nucleophilicity and fair nucleofugicity exhibited by phenoxy anion play a pivotal role in the SN2'' addition step.

Cooperative NHC and Photoredox Catalysis for the Synthesis of 1,4-Dicarbonyl Compounds via Diacylation of Alkenes.

An intermolecular 1,2-diacylation of alkenes is disclosed via cooperative N-heterocyclic carbene and photoredox catalysis under the mediation of PPh3 and Cs2CO3. This protocol provides a practical approach for construction of 1,4-dicarbonyl compounds toward novel diketone and pharmaceutical derivatives. Furthermore, the regioselective dicarbonyl compounds can be synthesized by adding acyl azolium salt. Mechanistic investigations suggest that the process was a critical radical/radical cross coupling of ketyl radicals with benzylic C-radicals.

Regioselective Alkylpolyfluoroarylation of Styrenes by Copper-Catalyzed C(sp3)-H and C(sp2)-H Double Activation.

A novel dehydrogenative dicarbofunctionalization of vinyl arenes with polyfluoroarenes and unactivated alkanes enabled by copper catalysis has been accomplished under mild conditions. This transformation provides a regioselective route to highly functionalized polyfluoroaryl compounds that occur as structural scaffolds in a variety of pharmaceuticals and materials. Preliminary mechanistic studies indicate that the carbon-based radical and copper intermediate are involved in the reaction, and the reaction pathway is dominated by the bond dissociation energy (BDE) of C(sp3)-H bonds.

Copper-Catalyzed Perfluoroalkylation of Alkynyl Bromides and Terminal Alkynes.

A copper-catalyzed one-pot perfluoroalkylation of alkynyl bromides and terminal alkynes has been disclosed, and the corresponding perfluoroalkylated alkynes could be attained in good to excellent yields. The new straightforward transformation shows high efficiency (0.01-0.5 mol % catalyst loading), broad substrate scope, and remarkable functional group tolerance and provides a facile approach for useful application in life and material sciences.

Silver-Mediated Perfluoroalkylation of Terminal Alkynes with Perfluoroalkyl Iodides.

The incorporation of a perfluoroalkyl group (RF) into drug candidates has become an increasingly important strategy in drug molecule design. In this study, the silver-mediated perfluoroalkylation reaction based on the addition-elimination process of terminal alkynes which was initiated by a perfluoroalkyl radical to form a C(sp)-RF bond has been developed. The reaction proceeds under mild conditions using readily available, low-cost perfluoroalkyl iodides as the sources of the RF group. This method allows access to a variety of perfluoroalkylated alkynes.

P(NMe2)3 mediated cyclopropanation of α-methylene-ß-lactams for rapid syntheses of spirocyclopropyl ß-lactams.

An expedient cyclopropanation of α-methylene-ß-lactams with α-ketoesters mediated by P(NMe2)3 has been developed. This reaction enables rapid access to a series of functionalized spirocyclopropyl ß-lactams in good yields from bench-stable starting materials under mild conditions. The experimental results indicated that the C3-substituent of the α-methylene-ß-lactam not only significantly impacted the reaction efficiency and stereochemistry but also played a pivotal role in determining the chemoselectivity of the reaction.

Copper-Catalyzed Perfluoroalkylation of Allyl Phosphates with Stable Perfluoroalkylzinc Reagents.

A general and practical method for copper-catalyzed cross-coupling of allyl phosphates with stable perfluoroalkylzinc reagents has been developed. The reaction proceeds under mild reaction conditions with high efficiency, good functional group tolerance, and high regio- and stereoselectivities and provides general, straightforward, and useful access to allyl-perfluoroalkyl compounds. Preliminary mechanistic studies reveal that the allyl copper intermediate may be involved in the catalytic cycle.

Copper-Catalyzed Oxidative Perfluoroalkylation of Aryl Boronic Acids Using Perfluoroalkylzinc Reagents.

An efficient and synthetically convenient method for copper-catalyzed cross-coupling of aryl boronic acids with perfluoroalkyl zinc reagents has been described. The reaction proceeds under mild reaction conditions with a high efficiency and broad substrate scope and provides a general access to perfluoroalkylated arenes, which are of interest in life and materials science.

Pd-catalyzed direct arylation of nitro(pentafluorosulfanyl)benzenes with aryl bromides.

Limited methods for the synthesis of SF5-substituted compounds significantly restrict their widespread application. A Pd-catalyzed direct arylation of nitro(pentafluorosulfanyl)benzenes with aryl bromides is reported. This protocol provides a facile and straightforward access to diversified SF5-containing aryl derivatives. The notable features of this reaction are its synthetic simplicity, high reaction efficiency, and good regioselectivity.

Copper- and phosphine-ligand-free palladium-catalyzed direct allylation of electron-deficient polyfluoroarenes with allylic chlorides.

Simply id(all)ylic: a copper- and phosphine-ligand-free Pd-catalyzed direct allylation of electron-deficient polyfluoroarenes with allylic chlorides and the reaction mechanism are described. The simple catalytic system, broad substrate scope, and excellent functional-group compatibility of this protocol provides a useful and facile access to allylated polyfluoroarenes.

Copper-catalyzed dehydrogenative cross-coupling of benzothiazoles with thiazoles and polyfluoroarene.

A copper-catalyzed dehydrogenative cross-coupling of benzothiazoles with thiazoles and polyfluoroarene under mild reaction conditions is described. This protocol provides a straightforward and operationally simple method for the synthesis of the 2,2'-linkage of thiazoles and 2-polyfluoroarylthiazoles of interest in life and material sciences.

Pd-catalyzed direct cross-coupling of electron-deficient polyfluoroarenes with heteroaromatic tosylates.

We report a Pd-catalyzed direct cross-coupling of electron-deficient polyfluoroarenes with heteroaromatic tosylates. The notable features of this reaction are its high reaction efficiency, excellent chemoselectivity, operational simplicity, and mild reaction conditions. We have applied this protocol to prepare the semiconducting materials in a highly efficient manner.