Palladium-catalyzed Stille Coupling Reaction Research Articles

Synthesis and photovoltaic properties of mono-substituted quaterthiophenes bearing strong electron-withdrawing group

We report here on the synthesis and properties of a monosubstituted quaterthiophene derivative asymmetrically functionalized by an electron-withdrawing group using the palladium-catalyzed Stille's coupling reaction. The UV–vis absorption spectrum evidences a strong intramolecular charge transfer transition. Thus oligothiophenes act as electron donors and substituent group as acceptor. The diodes in which monosubstituted quaterthiophenes behave as organic semiconductors, exhibit a rectifying behavior. Photovoltaic measurements show moderate power conversion efficiency.

Synthesis and characterization of thienylene–phenylene copolymers with oligo(ethylene oxide) side chains

A series of novel soluble conjugated regioregular copolymers (poly(2,5-dialkoxy-p-phenylene thienylenes)) was prepared via palladium-catalyzed Stille coupling reactions. The attachment of ethylene oxide chains to the phenylene rings ((OCH2CH2)nOR; n = 2, R = Me; n = 2, R = Bu; n = 3, R = Me) provided to the polymer increased solubility in polar solvents improved adhesion properties on glass substrates and complexing properties towards lithium ions. The structure of the polymers was established by FTIR, 1H and 13C NMR spectroscopy and elemental analysis. The physical properties were studied by X-ray diffraction, cyclic voltammetry, UV–Vis absorption and fluorescence, and Raman spectroscopy. The electrochemical properties of the copolymers compare favorably to those of the active materials used in electro-optical devices such as LED, LEC and electrochromic devices. Compared to related phenylene–thienylene copolymers the reported new materials showed lower values of the band gap and of the oxidation potential which is indicative of a highly conjugated π-system.

A Convenient Diversification of Pyrrolo[2,3-b]quinolines by Iodonation and Palladium-catalyzed Coupling Reactions

The 2-trimethylsilylpyrrolo[2,3-b]quinolines were easily transformed into 2-iodopyrrolo[2,3-b]quinolines under NIS/CH 3 CN. The palladium-catalyzed Heck, Stille, and Suzuki coupling reactions of 2-iodo[2,3-b]quinolines provided diverse 1,2,3-trisubstituted pyrrolo[2,3-b]quinolines in moderate to high yields.

Synthesis and properties of pyrimidine-containing linear molecules

Palladium-catalyzed Stille and Sonogashira coupling reactions were sequentially applied for constructing novel pyrimidine-containing linear molecules. The chemoselectivity of 5-bromo-2-iodopyrimidine ( 1 ) towards Pd-catalyzed coupling reaction serves as a tool for the successful control of the arrangement of dipolar pyrimidine moieties inside the conjugated backbone. The influence of the arrangement of dipolar pyrimidine in the linear backbone on their absorption and photoluminescence are not stupendous. Thermogravimetric analysis (TGA) indicate that all linear molecules in this study exhibit high thermal stability.

IMDA reaction in a synthetic approach towards a natural kijamicin aglycon analog

In our program of new macrocyclic antibiotic derivatives synthesis, a natural kijamicin analog was isolated, disclosing important antibiotic and antiviral properties, which are under investigation. In this paper we describe a synthesis of the bottom half C1-C14 (n = 1) of its aglycon. This strategy was based on the preparation of a tetraene derivative via a palladium catalyzed Stille coupling reaction, the final step involving an IMDA cyclization key step. Dans notre programme de recherche de nouveaux antibiotiques, un analogue naturel de la kijamycine a été isolé ; il a été montré quˈil présentait des propriétés antibiotiques et antivirales, qui sont actuellement à lˈétude. Nous décrivons dans ce travail la partie sud C1–C14 (n = 1) de son aglycone. Cette stratégie de synthèse est basée sur la préparation dˈun tétraène via une réaction de couplage de Stille catalysée au palladium, lˈétape clé finale mettant en jeu une réaction de Diels–Alder intramoléculaire.

Synthesis of highly ethynylated mono and dinuclear Pt(II) tethers bearing the 4,4′-bis(ethynyl)biphenyl (debp) unit as central core

Mono and bisubstituted bis(ethynyl)biphenyl Pt(II) complexes, i.e. trans-[(RCC)Pt(PPh 3) 2(CC p-C 6H 4 p-C 6H 4CCH)], R= p-NO 2C 6H 4 ( 3b), (η 5-C 5H 5)Fe(η 5-C 5H 4) ( 3c), and trans-[(RCC)Pt(PPh 3) 2(CC p-C 6H 4 p-C 6H 4CC)Pt(PPh 3) 2(CCR)], R=C 6H 5 ( 4a) , p-NO 2C 6H 4 ( 4b), (η 5-C 5H 5)Fe(η 5-C 5H 4) ( 4c), have been synthesized by the dehydrohalogenation reaction from the appropriate Pt monochloro acetylides trans-[(RCC)Pt(PPh 3) 2Cl], R=C 6H 5 ( 1a), R= p-NO 2C 6H 4 ( 1b), R=(η 5-C 5H 4)Fe(η 5-C 5H 5) ( 1c) and HCC p-C 6H 5 p-C 6H 5CCH, (4,4′-bis-ethynylbiphenyl), (DEBP) ( 2). In order to make possible a direct evaluation of the role of Pt centers on the properties of these highly ethynylated complexes, the corresponding species without Pt were prepared, i.e. C 6H 5CCCCC 6H 4C 6H 4CCCCC 6H 5, (4,4′-(bis-phenylethynyl)-diethynylbiphenyl) ( 7), and (η 5-C 5H 5)Fe(η 5-C 5H 4)(CCCCC 6H 4C 6H 4CCCC)(η 5-C 5H 4)Fe(η 5-C 5H 5), (4,4′-(bis-ferrocenylethynyl)-diethynylbiphenyl) ( 8). Preparation of the latter compounds was only achieved by the use of the palladium catalyzed Stille coupling reaction, since the dehydrohalogenation route afforded only homocoupled and polymeric products. The electron-donor or electron-withdrawing ligands coordinated to Pt were chosen for the purpose of tuning the optical properties of the complexes through the different charge distribution along the π-electron conjugation. Characteristic spectroscopic features (UV–vis, FT-IR and NMR) of these complexes are discussed.

An efficient synthesis of 2-(3-(4-amidinophenylcarbamoyl)naphthalen-2-yl)-5-((2,2-methylpropyl)carbamoyl)benzoic acid: a factor VIIa inhibitor discovered by the Ono Pharmaceutical Company

A small molecule factor VIIa inhibitor has recently been reported by the Ono Pharmaceutical Company. Herein, we outline an efficient and convergent, synthetic route that relies upon a palladium-catalyzed Stille coupling reaction as a key step for the synthesis of the inhibitor.

A chiral conjugated oligomer based on 1,1′-binaphthol with 3,3′-acetylene spacer

A 1,1′-binaphthol based optically active oligomer 6 with 3,3′-acetylene spacer was prepared from 2,2′-dimethoxy-1,1′-binaphthalene 3 through the palladium-catalyzed Stille coupling reaction. The high optical rotation and CD spectrum varified the main chain chirality of the oligomer. The photophysical properties of 6, absorption, excitation and fluorescent spectra, demonstrated that the oligomer molecule had a conjugated structure, but twisting and rigid conformation would reduce the delocalization along the backbone.

Synthesis and Electronic Properties of Aldehyde End-Capped Thiophene Oligomers and Other α,ω-Substituted Sexithiophenes

A series of α,ω-aldehyde end-capped oligomers of thiophene with three, four, five, six, and eight thiophene units have been synthesized using the palladium-catalyzed Stille's coupling reactions. The UV−vis spectral data indicate that these aldehyde end-capped oligomers have longer conjugation lengths as evidenced by the higher λmax values than the corresponding unsubstituted oligothiophenes. The λmax value increases as the number of thiophene units is increased. The intrinsic conductivity of the solution-cast films of the aldehyde end-capped oligothiophenes is generally higher than that of their corresponding unsubstituted counterparts. Other α,ω-substituted sexithiophenes, such as n-dodecanoyl, tert-butyldimethylsilyl, hydroxymethyl, and [(n-butoxyethoxy)ethoxy]methyl sexithiophenes, have also been synthesized. α,ω-Bis([(n-butoxyethoxy)ethoxy]methyl)sexithiophene has a remarkably high solubility in chloroform (1.8 g/L) and a conductivity (1 × 10-6 S/cm) comparable to the unsubstituted sexithiophene.