Palladium-catalyzed Suzuki Coupling Research Articles

1,1′-Methylene-3,3′-bis[(N-(tert-butyl)imidazol-2-ylidene] and Its Effect in Palladium-Catalyzed C–C Coupling

A catalytic system utilizing a chelate carbene ligand containing bulk <i>tert</i>-butyl groups is described for palladium-catalyzed Heck and Suzuki coupling reactions. The Heck reaction focused on the coupling of different aryl bromides with mono- and 1,1-disubstituted olefins while the Suzuki reaction involved the coupling of aryl bromides and phenylboronic acid to afford the corresponding biphenyls. The catalyst system performs well with low Pd(OAc)₂ levels (0.025 mol% Pd). In all cases with monosubstituted olefins, the <i>trans</i>-configured products were obtained, while the results of Heck reaction of 1,1-disubstituted olefins exhibited a high selectivity favoring the terminal product.

Bifurans via Palladium-Catalyzed Suzuki Coupling

Bifurans via Palladium-Catalyzed Suzuki Coupling

Palladium-Catalyzed Suzuki Coupling towards 2-Amino-1,8-naphthyridines

Palladium-Catalyzed Suzuki Coupling towards 2-Amino-1,8-naphthyridines

ChemInform Abstract: Palladium‐Catalyzed Synthesis of Biaryl Ketones via tert‐Butyl Isocyanide Insertion.

A simple and efficient palladium-catalyzed carbonylative Suzuki coupling via tert-butyl isocyanide insertion has been developed, which demonstrates the utility of isocyanides in intermolecular C–C bond construction. This methodology provides a novel pathway for the synthesis of diaryl ketones in moderate to good yields. The approach is tolerant to a wide range of substrates and applicable to library synthesis. A possible reaction mechanism was proposed based on the experimental results.

Solution-Processable Organic Photovoltaic Cell Based on the Oligothiophene with Solubilizing β-alkyl Groups

We synthesized a linear π-conjugated small molecule (β-DH5T) based on thiophene, using the palladium-catalyzed Suzuki coupling. The oligothiophene was designed to contain β-substituted solubilizing alkyl groups to facilitate solution processing. The organic photovoltaic cell based on β-DH5T:PC71BM gave a power conversion efficiency of 0.46% with a short-circuit current of 4.69 mA/cm2, an open-circuit voltage of 0.60 V, and a fill factor of 0.35, giving under AM 1.5G illumination (100 mW/cm2). The optical and electrochemical properties and molecular alignment of oligothiophene were investigated using UV-visible absorption spectroscopy, cyclic voltammetry, and thin-film X-ray diffraction studies.

Synthesis and characterization of a new poly(octathiophene) based copolymer for organic thin-film transistor.

A new poly(octathiophene) based copolymer was designed and synthesized by the palladium catalyzed Suzuki coupling reaction. The structure of the newly obtained copolymer was confirmed by 1H-NMR and IR. The number-average molecular weight (M(n)) of the polymer was 36,000 with a poly-dispersity index of 1.15. The polymer has good solubility in common solvents such as chloroform, toluene, chlorobenzene, dichlorobenzene and tetrahydrofuran at room temperature. The optical, thermal and electrochemical properties of the polymer were characterized by UV-vis absorption, TGA and DSC and cyclovoltametry, respectively. A thin film transistor using the new polymer as an organic semiconductor was found to exhibit typical p-channel FET characteristics with a hole mobility of 5 x 10(-4) cm2/Vs.

Synthesis and Photovoltaic Properties of Moderate Band Gap Diketopyrrolopyrrole Based Small Molecules for Solution Processed Organic Solar Cells

Two new small molecules, based on diketopyrrolopyrrole core flanked by cyanothiophene units (CN-DPP-CN, CN-TH-DPP-TH-CN) were synthesized using CuCN and palladium catalyzed Suzuki coupling and explored in organic solar cells (OSCs). The HOMO/LUMO energy levels of CN-DPP-CN, CN-TH-DPP-TH-CN having moderate band gap of 1.83 eV and 1.44 eV were estimated to be −5.63/−3.84 eV, −5.20/−3.75 eV respectively. The device efficiency was found to be 0.013, 0.21% for CN-DPP-CN, CN-TH-DPP-TH-CN respectively as donors for BHJ solar cells. When CN-DPP-CN (0.05%) was added in P3HT:PC60BM device, its PCE was enhanced to 2.45% from 2.08% signifying its ability to be used as potential n-type additive.

A polyphenylene support for Pd catalysts with exceptional catalytic activity.

We describe a solid polyphenylene support that serves as an excellent platform for metal-catalyzed reactions that are normally carried out under homogeneous conditions. The catalyst is synthesized by palladium-catalyzed Suzuki coupling which directly results in formation of palladium nanoparticles confined to a porous polyphenylene network. The composite solid is in turn highly active for further Suzuki coupling reactions, including non-activated substrates that are challenging even for molecular catalysts.

Improved Performance of Solution-Processed n-Type Organic Field-Effect Transistors by Regulating the Intermolecular Interactions and Crystalline Domains on Macroscopic Scale

The development of four new n-channel naphthalene diimide (NDI) and perylene diimide (PDI) copolymers (NDI-Ph, NDI-BT, PDI-Ph, and PDI-BT) and their solution processed thin film transistor (TFT) devices are reported. Remarkable enhancements in the electron transport behavior for all the four copolymers were achieved on improving the intermolecular interactions in their thin film structures. These solution processable n-type copolymers having NDI and PDI backbone were synthesized in high yields (83–86%) by palladium catalyzed Suzuki coupling reactions, and their excellent solubility in several organic solvents allowed their deposition in organic thin film transistor (OTFT) devices from solution directly. Since these copolymers possess crystalline domains, annealing their films induced crystalline phases in the thin film structures with a very high degree of enhancement in crystallinity that was more prominent for PDI copolymers as compared to NDI derivatives. This resulted in significant enhancement in the...

ChemInform Abstract: An Efficient and Simple Ligand from Phthalandione for Palladium‐Catalyzed Suzuki Reaction in Aqueous Media.

Abstract An efficient and simple ligand derived from phthalandione was used for palladium catalyzed Suzuki coupling reaction in water/ethanol (V/V = 2/1) under aerobic conditions. The reaction exhibited a high catalytic efficiency even with lower Pd loading (0.002 mol %). In this work, the catalyst could be successfully used in coupling reaction between various aryl halides with phenylboronic acid in excellent yields with high turnover number (TON) (the maximal TON was up to 49,000 for the reaction of bromobenzene with phenylboronic acid). Moreover, this new ligand had been elucidated by 1H NMR, 13C NMR and X-ray crystal diffraction.

Regio- and stereoselective synthesis of ferrocene-containing β-iodoallylic esters and ethers from the iodofunctionalization of ferrocenylallene with carboxylic acids, phenols, and alcohols.

The iodofunctionalization of ferrocenylallene with carboxylic acids, phenols, and alcohols is described. The reaction proceeds smoothly in the presence of molecule iodine as a halonium promoter and using various carboxylic acids, phenols, and alcohols as nucleophiles to give the corresponding ferrocene-containing β-iodoallylic ester and ether products in moderate to high yields and with high regio- and stereoselectivities. It can be envisaged that the regio- and stereoselectivity of this reaction may be controlled by the steric effect of the bulky ferrocene group. The presence of the C-I bond in the corresponding products makes these molecules highly attractive from a synthetic point of view, as it provides an opportunity for further transformations. Thus, palladium-catalyzed Heck coupling, Suzuki coupling, Sonogashira coupling, and copper-catalyzed click reactions were carried out successfully.

Palladium-Catalyzed Synthesis of Biaryl Ketones via tert-Butyl Isocyanide Insertion

A simple and efficient palladium-catalyzed carbonylative Suzuki coupling via <i>tert</i>-butyl isocyanide insertion has been developed, which demonstrates the utility of isocyanides in intermolecular C–C bond construction. This methodology provides a novel pathway for the synthesis of diaryl ketones in moderate to good yields. The approach is tolerant to a wide range of substrates and applicable to library synthesis. A possible reaction mechanism was proposed based on the experimental results.

Anion Exchange Fuel Cell Membranes Prepared from C–H Borylation and Suzuki Coupling Reactions

Of the polymer materials investigated as anion exchange membranes, trimethylbenzylammonium-containing polysulfones are the most extensively studied. They are commonly prepared by chloromethylation of the aromatic backbone or radical bromination of benzylic carbons, followed by a Menshutkin reaction between a tertiary amine and the benzyl halide. To overcome synthetic limitations involved with these two methods, we report the preparation of an anion exchange membrane by means of iridium-catalyzed C–H borylation followed by palladium-catalyzed Suzuki coupling. Owing to the use of mild reaction conditions and high efficiency of these metal-catalyzed reactions, we were able to minimize side reactions and easily control the degree of functionalization for a series of trimethylbenzylammonium-containing polysulfones. The resulting membranes exhibited lower water uptake while maintaining similar hydroxide conductivity and functional group stability as compared to the corresponding chloromethylation-prepared anion exchange membrane materials.

ChemInform Abstract: Opening an Aladdin′s Cave: The Suzuki Coupling in a Room‐Temperature Ionic Liquid

AbstractReview: 30 refs.

Preparation and characterization of alternating copolymers containing fluorene and thiophene derivatives

A series of fluorene-based polymers with alkylsulfanyl, alkylsulfinyl and alkylsulfonyl substituted thiophene were synthesized by the palladium-catalyzed Suzuki coupling reaction and the structures were confirmed by nuclear magnetic resonance spectroscopy and mass spectrometry. The results of the absorption and emission spectra reveal that the substituents on the thiophene ring strongly affect the planarity of the polymer chains. The interruption of the effective conjugation length through the non-planar conformation results in high photoluminescence quantum yield. Cyclic voltammetry analysis of the polymers was observed that the non-planar polymers increased the band gap and decreased the highest occupied molecular orbital level. Differential scanning calorimetry trace confirmed that the less steric hindrance of substituents on the thiophene ring would increase the intermolecular interaction and the crystallinity of the polymers.

Opening an Aladdin's cave: the Suzuki coupling in a room-temperature ionic liquid

This viewpoint will discuss the impact of the 2000 Chem. Commun. report that the palladium-catalysed Suzuki coupling can be performed quickly and easily in a room-temperature ionic liquid. This work has helped fuel what have now become whole areas of chemistry of their own: the use of ionic liquids as reaction media for catalytic transformations, and the application of palladium complexes bearing N-heterocyclic carbene (NHC) ligands in the Suzuki coupling and beyond.

Highly Solution-Processible Red Light-Emitting Conjugated Polymers Based on Benzothiadiazole

A series of high molecular weight，readily soluble conjugated copolymers derived from 9,9-dioctylfluorene (DOF) and 4,7-di(3- hexylthien-2-yl)-2,1,3-benzothiadiazole (DHTBT) were designed and synthesized by a palladium-catalyzed Suzuki coupling reaction with different ratios of DOF to DHTBT. Thermal stability, solubility, absorption spectra, photoluminescent spectra and electrochemical of the copolymers were investigated in detail. In the solid film, these copolymers showed saturated red light. These properties made them potential soluble red light-emitting candidates for polymer light-emitting diodes.

An efficient and simple ligand from phthalandione for palladium-catalyzed Suzuki reaction in aqueous media

An efficient and simple ligand derived from phthalandione was used for palladium catalyzed Suzuki coupling reaction in water/ethanol (V/V=2/1) under aerobic conditions. The reaction exhibited a high catalytic efficiency even with lower Pd loading (0.002mol%). In this work, the catalyst could be successfully used in coupling reaction between various aryl halides with phenylboronic acid in excellent yields with high turnover number (TON) (the maximal TON was up to 49,000 for the reaction of bromobenzene with phenylboronic acid). Moreover, this new ligand had been elucidated by 1H NMR, 13C NMR and X-ray crystal diffraction.

Palladium-Catalyzed Coupling Reactions for the Functionalization of Si Surfaces: Superior Stability of Alkenyl Monolayers

Palladium-catalyzed Suzuki, Heck, and Sonogashira coupling reactions were studied as reaction protocols for organic modification of Si surfaces. These synthetically useful protocols allow for surface modification of alkene, alkyne, and halide terminated surfaces. Surface oxidation and metal contamination were assessed by X-ray photoelectron spectroscopy. The nature of the primary passivation layer was an important factor in the oxidation resistance of the Si surface during the secondary functionalization. Specifically, the use of alkynes as the primary functionalization layer gave superior stability compared to alkene analogues. The ability to utilize Pd-catalyzed coupling chemistries on Si surfaces opens great versatility for potential molecular and nanoscale electronics and sensing/biosensing applications.

Naphthodifuranone-Based Monomers and Polymers

The synthesis of new π-conjugated monomers and polymers containing 3,8-bisphenylnaphtho[2,1-b:3,4-b′]difuran-2,9-dione (1,10-NDF) units in the main chain is described. 1,10-NDF-monomer M1 (3,8-bis(4-bromophenyl)naphtho[2,1-b:3,4-b′]difuran-2,9-dione) was obtained upon condensation of 2,3-dihydroxy-naphthalene and 4-bromo-mandelic acid followed by oxidation with nitrobenzene. M2 (3,8-bis(4-(5-bromo-4-octylthiophen-2-yl)phenyl)naphtho[2,1-b:3,4-b′]difuran-2,9-dione) was obtained upon Stille coupling of 4-n-octylthiophen-2-yl-trimethylstannane and M1 followed by bromination of the thiophene groups with NBS. The X-ray structure analysis of M1 indicated a dihedral angle of 42–45° between the lactam phenyl groups and the NDF core, and weak intermolecular π–π stacking with a distance of 3.36 Å between the chromophors. A HOMO–LUMO calculation of M1 indicates an electron transfer from the phenyl groups to the NDF core upon excitation. Polymers were obtained upon palladium-catalyzed Suzuki and Stille coupling reactions of M1 and M2 with 2,2-(9,9-dioctyl-9H-fluorene-2,7-diyl)bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolane) and 2,5-bis(tributylstannyl)thiophene. The polymers exhibit broad absorption bands with maxima between 508 and 564 nm and tails reaching up to 1057 nm in thin films, and high extinction coefficients of 1.1 × 104 to 3.9 × 104 L mol–1 cm–1. Band gaps are between 1.45 to 1.63 eV. Photoirradiation studies indicate that the polymers are extremely stable to UV and visible light.