Search

This paper describes the nickel-catalyzed reductive alkylation of aroyl fluorides with alkyl bromides in a decarbonylative manner. In this reaction, various functional groups are well tolerated and the C(

Numerous studies on the activation of carbon–fluorine bonds have been reported in recent years. For example, acyl fluorides have been utilized as versatile reagents for acylation, arylation, and even fluorination. In this review, we focus on acyl fluorides as compounds with carbon–fluorine bonds, and highlight recent advances in strategies for the activation of their C–F bonds via transition-metal catalysis, N-heterocyclic carbene (NHCs) catalysis, organophosphine catalysis, and classical nucleophilic substitution reactions.1 Introduction2 Transition-Metal-Mediated C–F Bond Activation2.1 Acylation (Carbonyl-Retentive) Coupling Reactions2.2 Decarbonylative Reactions2.3 C–F Bond Activation by Other Transition Metals3 C–F Bond Activation by N-Heterocyclic Carbenes (NHCs)3.1 NHC-Catalyzed Cycloaddition of Acyl Fluorides3.2 NHC-Catalyzed Radical Functionalization of Acyl Fluorides3.3 NHC-Catalyzed Nucleophilic Fluorination of (Hetero)aromatics4 C–F Bond Activation by Phosphines4.1 Phosphine-Catalyzed Direct Activation of the C–F Bond of Acyl Fluorides4.2 Phosphine-Catalyzed Indirect Activation of the C–F Bond of Acyl Fluorides5 C–F Bond Activation by Classical Nucleophilic Substitution6 Miscellaneous Examples7 Summary and Perspective

Nickel-catalyzed decarbonylative thioetherification of acyl fluorides has been developed. This transformation allows an array of acyl fluorides to react with thiophenols. A wide range of functional groups are well tolerated and the corresponding sulfides can be obtained in good to excellent yields. This protocol provides the formation of diverse carbon–sulfur bonds via a highly efficient decarbonylative process.

The activation of a carbon-fluorine bond is one of the most challenging topics in modern synthetic organic chemistry due to their low reactivity compared to other carbon-halogen bonds. In this review, we present the recent developments since 2015 on cross-coupling reactions that form C-C bonds via cleavage of C(sp2 )-F bonds. Not only the conventional activation of C(sp2 )-F bonds, but also decarbonylative or carbonyl-retentive cleavage of C(acyl)-F bonds will be introduced. This paper mainly describes new protocols for the formation of C(sp2 )-C(sp3 ), C(sp2 )-C(sp2 ), and C(sp2 )-C(sp) bonds via transition-metal-catalyzed cleavage of C(sp2 )-F bonds.

This paper describes the synthesis of unsymmetrical biaryls by the palladium-catalyzed cross-coupling reaction of acyl chlorides with potassium perfluorobenzoates. This transformation is unique in that it involves simultaneous decarbonylation and decarboxylation under redox-neutral conditions. Compared to conventional cross-coupling protocols for the synthesis of unsymmetrical biaryls, the two reactants in this synthetic strategy can be readily prepared from abundant and inexpensive aromatic carboxylic acids.

A simple and efficient strategy for iron-catalysed cascade radical cyclization was developed, by which an array of germanium-substituted indolo[2,1-a]isoquinolin-6(5H)-ones and indolin-2-ones were obtained in one pot with germanium hydrides as radical precursors. A rapid intramolecular radical trapping mode enabled the selective arylgermylation of alkenes over the prevalent hydrogermylation reaction.

Nickel-catalyzed decarbonylative alkynylation of acyl fluorides with terminal silylethynes under copper-free conditions is described. This newly developed method has a wide substrate scope, affording internal silylethynes in moderate to high yields. The formation of 1,3-diynes as homocoupled products and conjugate enones as carbonyl-retentive products were effectively suppressed.

Iron-catalyzed alkylative cyclization of alkenes bearing oxygen nucleophiles with secondary and tertiary alkyl bromides through carbon-carbon and carbon-oxygen bond formations has been developed. A broad substrate scope is an attractive feature of this synthetic method, providing a variety of potentially bioactive five- and six-membered oxygen-containing heterocycles. The reaction pathway is proposed to involve a radical addition of the in situ-formed alkyl radical to an alkene followed by carbon-oxygen bond-forming intramolecular cyclization.

Palladium/copper-cocatalyzed decarbonylative alkynylation of acyl fluorides with alkynylsilanes is described. This reaction not only effectively inhibits the formation of undesired homocoupled products by avoiding the addition of a base, but also exhibits a wide substrate scope to provide a general access to diverse unsymmetrical diarylethynes.

Libraries of polynorbornadienes were synthesized with good yields with a ruthenium-containing 2nd generation Grubbs catalyst by ring-opening metathesis polymerization (ROMP) of a variety of symmetric and non-symmetric 2,3-bis(alkoxycarbonyl)norbornadiene monomer units prepared from the half-esters obtained efficiently by the selective monohydrolysis reactions of symmetric diesters we reported earlier. Among these polymers, the polynorbornadienes with t-butoxycarbonyl groups derived from non-symmetric monomer units were converted to the half-ester derivatives by deprotection with trifluoroacetic acid, yielding amphiphilic polymers. The hydrogenation reactions of the obtained polymers were carried out to yield polymers having saturated structures in the main chains for improvement of the thermal stabilities. All these polymers were characterized by their molecular weights and thermal properties along with the spectroscopic data. Our selective monohydrolysis reactions have been proven to be a versatile tool for production of relatively homogeneous polymer libraries.

Copper-catalyzed regioselective aminothiolation of terminal and internal alkenes with N-fluorobenzenesulfonimide and thiols has been developed. The three-component reaction is promoted by the addition of dimethyl sulfide. In addition to aromatic alkenes, aliphatic alkenes are subjected to the reaction, affording various aminothiolation adducts as single regioisomers. The radical process is proposed by preliminary mechanistic studies, involving radical trap and radical clock experiments.

The Suzuki–Miyaura reaction (the cross-coupling reaction of boronic acids with organic halides catalysed by Pd complexes) has been recognised as a useful synthetic organic reaction that forms a C(sp2)–C(sp2) bond.

In this Letter, the palladium/copper-cocatalyzed arylsilylation of internal alkynes with acyl fluorides and silylboranes is described. This is the first example in which acyl fluorides have been utilized for the three-component coupling reaction via decarbonylation, yielding a variety of tetrasubstituted alkenylsilanes in moderate to good yields.

A simple and efficient strategy for iron-catalysed cascade radical cyclization was developed, by which an array of germanium-substituted indolo[2,1

Ni-catalyzed decarbonylative cyanation of acyl chlorides with trimethylsilyl cyanide has been achieved. This transformation is applicable to the synthesis of an array of nitrile compounds bearing a wide range of functional groups under neutral conditions. The step-by-step experimental studies revealed that the reaction sequences of the present catalytic reaction are oxidative addition, transmetalation, decarbonylation, and reductive elimination.

Bis[1]benzothieno[5,4-d:5′,4′-d′]benzo[1,2-b:4,5-b′]dithiophene (BBTBDT-2) and its phenyl-substituted derivative were successfully synthesized and characterized. From DFT calculations, highest occu...

Bidentate phosphine-assisted methylenation of acyl fluorides and acyl chlorides with substituted with aryl, alkenyl, and alkyl groups trimethylaluminum afforded an array of 2-substituted propene derivatives. The addition of a catalytic amount of DPPM increased an efficiency of the reactions. Trimethylaluminum as the methylenation reagent not only eliminates the presynthesis of methylene transfer reagent, but provides an efficient method for the synthesis of a series of 2-substituted propenes.

A new class of an acceptor unit, vinylene-bridged 5,6-difluorobenzothiadiazole FBTzE, has been developed. Palladium-catalyzed Migita–Kosugi–Stille coupling reactions of 1 with 2, yielding 3 and its sequential dehydrogenative coupling with 4, readily afforded FBTzE-containing monomers 5a–5c that have lower lowest unoccupied molecular orbital (LUMO) energy level and smaller energy gap than those of 5,6-difluorobenzothiadiazole (DFBT). Subsequently, three types of FBTzE-containing copolymers 3T, 4T, and 2TTT were synthesized by Migita–Kosugi–Stille coupling of monomers 5b and 5c with distannylated thiophene, bithiophene, and thienothiophene, respectively and their physicochemical properties and solar cell performances were evaluated. As a result of cyclic voltammogram, the synthesized FBTzE-based polymers have deeper highest occupied molecular orbital (HOMO) and LUMO energy levels, and stronger intermolecular interactions than those of DFBT-based polymer PffBT4T-DT. Although 3T/PC61BM blended film formed favorable face-on orientation with short dπ of 3.57 A, its solar cell showed poor PCE of 2.7% owing to the construction of large phase separation structure with a domain size over 100 nm. In a sharp contrast, 2TTT/PC61BM formed unsuitable edge-on orientation with short dπ of 3.49 A, but its film formed optimal nanoscale phase separation, leading to a good performance with PCE of up to 5.2%.

The activation of a carbon-fluorine bond is one of the most challenging topics in modern synthetic organic chemistry due to their low reactivity compared to other carbon-halogen bonds. In this review, we present the recent developments since 2015 on cross-coupling reactions that form C-C bonds via cleavage of C(sp

The synthesis of a dimeric boryloxorhodium complex having the Rh–O–Bpin scaffold from the reaction of [(cod)Rh(OMe)]2 or [(cod)Rh(OH)]2 with an arylboronate has been achieved. The obtained dirhodium complex is converted into mononuclear complex [(cod)Rh(OBpin)(PPh3)], which reacts with arylboronic acid to afford the complex with an Rh-aryl bond via transmetalation from boron to rhodium. The dimeric boryloxorhodium complex catalyzes the 1,4-addition of arylboronic acid to cyclohexene-2-one.

We report the transition metal-free decarboxylative cross-coupling reactions of acyl fluorides with potassium perfluorobenzoates. Compared with traditional transition metal-catalyzed cross-couplings, this protocol presents an extremely environmentally benign pathway to afford unsymmetrical diaryl ketones. To install perfluorophenyl groups, this method highlights highly selective, inexpensive, and nontoxic conditions. The reaction system tolerates various functional groups in acyl fluorides. Remarkably, all of the starting materials can be prepared from abundant carboxylic acids and the reaction proceeds without any catalysts and additives.

Acyl fluorides are subjected to methoxylation with tris(2,4,6-trimethoxyphenyl)phosphine (TMPP) to afford the corresponding methyl esters in good to excellent yields. This transformation is featured by C(

To investigate organic field-effect transistor (OFET) properties, a new thienoacene-type molecule, 4,14-dihexyldinaphtho[2,3-d:2&rsquo, 3&rsquo, d&rsquo, ]anthra[1,2-b:5,6-b&rsquo, ]dithiophene (C6-DNADT), consisting of &pi, conjugated nine aromatic rings and two hexyl chains along the longitudinal molecular axis has been successfully synthesized by sequential reactions, including Negishi coupling, epoxidation, and cycloaromatization. The fabricated OFET using thin films of C6-DNADT exhibited p-channel FET properties with field-effect mobilities (&micro, ) of up to 2.6 &times, 10&minus, 2 cm2 V&minus, 1 s&minus, 1, which is ca. three times lower than that of the parent DNADT molecule (8.5 &times, 1). Although this result implies that the installation of relatively short alkyl chains into the DNADT core is not suitable for transistor application, the origins for the FET performance obtained in this work is fully discussed, based on theoretical calculations and solid-state structure of C6-DNADT by grazing incidence wide-angle X-ray scattering (GIWAXS) and atomic force microscopy (AFM) analyses. The results obtained in this study disclose the effect of alkyl chains introduced onto the molecule on transistor characteristics.

Palladium-catalyzed decarbonylative alkylation reactions of acyl fluorides have been developed using alkylboranes having β-hydrogens. A wide range of functional groups were well tolerated, even at the high temperature required for decarbonylation. This protocol provides a diverse C(sp2)–C(sp3) bond formation via a highly efficient decarbonylative process. The hemilabile bidentate ligand DPPE plays a crucial role for retardation of the undesired β-hydride elimination.

Carboxylic acid derivatives containing acyl halides, anhydrides, esters, amides and acyl nitriles are highly appealing electrophiles in transition-metal-catalyzed carbon-carbon bond-forming reactions due to their ready availability and low cost, which can provide divergent transformations of carboxylic acids into other value-added products. In this Minireview, we focus on the recent advances of decarbonylative transformations of carboxylic acid derivatives in carbon-carbon bond formations using Ni or Pd catalysts. A series of reaction types, product classifications and reaction pathways are presented herein, which show the advantageous features of carboxylic acid derivatives as alternative to aryl or alkyl halides in terms of reactivity and compatibility. The well-accepted mechanism of nickel- or palladium-catalyzed decarbonylative transformations involves initial oxidative addition of carboxylic acid derivatives, followed by decarbonylation or transmetalation (or insertion), and reductive elimination to generate the products, thereby regenerating the catalysts.

Copper-catalyzed regioselective aminothiolation of terminal and internal alkenes with

A new type of thiadiazole-based acceptor unit and its donor–acceptor copolymers were synthesized and characterized to develop the high-performance semiconducting polymers for organic field-effect transistors (OFETs) and organic photovoltaics (OPVs). We successfully synthesized an anthra[1,2-c:5,6-c′]bis([1,2,5]thiadiazole) (ATz) core and ATz-quaterthiophene copolymers. These copolymers possess a wide energy gap of ca. 1.8 eV and a deeper HOMO energy levels around −5.4 eV than that of typical thiadiazole–oligothiophene copolymers. Such weak electron-accepting nature may be due to the decreased electron affinity of the ATz core by an existence of alkoxy groups with strong electron-donating ability. The ATz copolymers exhibited good semiconducting properties with hole mobility of up to 0.03 cm2 V–1 s–1 and photovoltaic response with PCE of up to 5.7%, despite the unfavorable molecular orders, thin-film structure, and/or amorphous structure.

The incorporation of a highly extended π-electron system into a polymer backbone is an effective strategy to develop high-performance donor–acceptor (D–A) polymers suitable for organic electronics because this strategy can facilitate a dense π-π stacking structure, leading to efficient carrier transport. With this in mind, we developed phenanthro[1,2-b:8,7-b′]dithiophene (PDT) because this new phenacene-type molecule has a highly crystalline nature, deep HOMO level, and high hole mobility, which are characteristics known to be suitable for a donor unit in high-performance D–A polymers. In this focus review, we report recent progress in PDT-containing D-A polymers combined with various strong acceptor units. Incorporation of PDT into a polymer backbone results in deep HOMO energy levels of −5.4~−5.5 eV, strong aggregation, and a dense packing structure with a short π-stacking distance of 3.5~3.6 A. PDT-based polymers with appropriate alkyl side chains exhibit high hole mobilities of up to 0.18 cm2 V−1 s−1 in organic field-effect transistor (OFET) devices due to their tendency to form highly ordered edge-on structures. Furthermore, we can adjust their level of molecular orientation from edge-on to face-on by increasing their molecular weight, leading to a high power conversion efficiency of over 6% in polymer solar cell (PSC) applications. These results demonstrate that PDT is a good candidate as a high-performance building block in D-A polymers. A recent progress of phenanthro[1,2-b:8,7-b′]dithiophene (PDT)-based low bandgap semiconducting polymers combined with various strong acceptor units are described. By incorporating a highly π-extended PDT core into the polymer backbone, the synthesized polymers have deep HOMO energy levels and formed a dense packing structure with a short π-stacking distance. The PDT-based polymers with optimal side chains and high molecular weight exhibit high hole mobility of up to 0.18 cm−1 V−1 s−1 in organic field-effect transistors and high power conversion efficiency over 6%. These results indicate that PDT is a good π-framework as high-performance semiconducting polymers.

Four bis[1]benzothieno[6,7-d:6′,7′-d′]benzo[1,2-b:4,5-b′]dithiophene (BBTBDT) derivatives bearing substituents on the molecular long axis were synthesized, and their transistor performance was evaluated. Among the obtained compounds, OFET devices based on the 2,9-diphenyl-substituted derivative (1d) on a β-PTS-modified Si/SiO2 substrate yielded the best morphological and crystalline structures, resulting in the highest hole mobility, as high as 0.16 cm2 V–1 s–1, and a low threshold voltage of −8 V. In the solid state, 1d formed a highly ordered and crystalline edge-on structure, which facilitated effective carrier transport. The detailed structure–property relationships were also disclosed by GIWAXS analysis, atomic force microscopy measurements, and theoretical calculations.

Synthesis, characterization, and solar cell application of three 4,7-dialkylated phenanthro[1,2-b:8,7-b′]dithiophene (PDT)–difluorobenzothiadiazole (DFBT copolymers (P1–P3) with different linear alkyl side chains to improve solubility, molecular weight, and molecular orientation are described. The utilization of Ir-catalyzed direct borylation and sequential functionalization can selectively afford the target 4,7-dialkylated PDT as the monomers. Migita–Kosugi–Stille coupling in the presence of CuI can accelerate polymerization to afford high-molecular-weight polymers along with their improved solubility. The effect of alkyl substitution at the 4,7-positions on the electronic structure of PDT–DFBT copolymers is negligible. By installation of additional alkyl chains at the 4,7-positions of PDT, the synthesized polymers P1–P3 have lower intermolecular interaction than that of nonalkylated P0, but they still maintained aggregation behavior in solution. In addition, they formed a favorable face-on orientation w...

Transistor properties of two semiconducting polymers based on vinylene-bridged 5,6-difluorobenzo[c][1,2,5]thiadiazole (4T and 2TTT) and their structure-property relationship were investigated. Graz...

A copper-catalyzed chloroamination of alkenes with chlorotrimethylsilane and N-fluorobenzenesulfonimide has been developed. The reactions were complete within 1 h at 120 degrees C by means of microwave heating. The present chloroamination proceeds with a perfect regioselectivity and is compatible with various functional groups. The preliminary mechanistic investigation revealed that the reaction involves a radical process. The utility of the present method was demonstrated by scalable, operationally simple and safe system.