Stille Cross-coupling Reaction Research Articles

Utility of a heterogeneous palladium catalyst for the synthesis of a molecular semiconductor via Stille, Suzuki, and direct heteroarylation cross-coupling reactions

Demonstration of the utility of a commercially available heterogeneous palladium catalyst in the synthesis of a relevant high performance molecular semiconductor.

Computational Study on the C–Heteroatom Bond Formation via Stille Cross-Coupling Reaction: Differences between Organoheterostannanes Me3SnAsPh2 vs Me3SnPPh2

The formation of C–heteroatom bonds through the Stille cross-coupling reaction has been explored computationally within the density functional theory framework. To this end, the reaction profiles of the processes involving different aryl halides (PhCl, PhI) and heterostannanes (Me3SnZR2, Z = As, P; R = Ph, Me) in the presence of palladium catalyst have been investigated and compared to gain more insight into the differential reactivity observed experimentally. In addition, the main features of the reaction steps where the heterostannanes are involved, namely, the transmetalation and reductive elimination reactions, have been analyzed in detail. It was found that the overall relative reaction profile for the transmetalation step involving heterostannanes with Z = P is energetically favored over that involving species having Z = As, which agrees with the experimental observations. This can be mainly ascribed to the relative strength of the Sn–Z bond, which is broken during the transmetalation step (Sn–P < S...

Novel wide band-gap polymer utilizing fused hetero-aromatic unit for efficient polymer solar cells and field-effect transistors

Novel wide band-gap polymer of PBTFT containing dibenzosexithiophene-alt-bithiophene backbone was designed and synthesized via the Stille cross-coupling reaction. This polymer exhibited good thermal stability, well coplanar backbone and a broad absorption band from 350 nm to 610 nm with a wide optical band-gap of 2.02 eV. The polymer solar cells (PSCs) based on the PBTFT:PC71BM active layer showed the power conversion efficiency of 3.0% with an open circuit voltage of 0.70 V, a short-circuit current of 7.94 mA cm−2 and a fill factor of 53.98% under the illumination of AM.1.5, 100 mW cm−2. Holes mobility up to 0.028 cm2 V−1 s−1 with an on-off ratio of 1.0 × 106 was obtained in the PBTFT-based organic field-effect transistors (OFETs). Our work indicates that the dibenzosexithiophene-alt-bithiophene based copolymer can be efficiently applied in PSCs and OFETs.

Advances in metal-catalyzed cross-coupling reactions of halogenated quinazolinones and their quinazoline derivatives.

Halogenated quinazolinones and quinazolines are versatile synthetic intermediates for the metal-catalyzed carbon–carbon bond formation reactions such as the Kumada, Stille, Negishi, Sonogashira, Suzuki-Miyaura and Heck cross-coupling reactions or carbon-heteroatom bond formation via the Buchwald-Hartwig cross-coupling to yield novel polysubstituted derivatives. This review presents an overview of the application of these methods on halogenated quinazolin-4-ones and their quinazolines to generate novel polysubstituted derivatives.

ChemInform Abstract: A Facile and Convenient Sequential Homobimetallic Catalytic Approach Towards β‐Methylstyrenes. A One‐Pot Stille Cross‐Coupling/Isomerization Strategy.

An efficient one-pot synthetic approach towards β-methylstyrenes is reported. The transformation, based on sequential homobimetallic catalysis, involves a Stille cross-coupling reaction between aryl halides and allyltributylstannane, followed by an in situ palladium-catalyzed conjugative isomerization. The reaction was optimized, and the best results were obtained with 10 mol% Pd(PPh3)2Cl2, 8.0 equiv. LiCl, and 0.5 equiv. PPh3 in diglyme at 130 °C for 12 h. It was demonstrated that the reaction tolerates a wide variety of functional groups.

A white emitting poly(phenylenevinylene)

A white emitting copolymer with the polyphenylenevinylene (PPV) structure is obtained via the Stille cross-coupling reaction. Substitution of hydrogen atoms with fluorine atoms on the vinylene units of poly(1,4-dialkoxyphenylenevinylene) shifts the emission from orange-red to blue. White emission is obtained by combining dialkoxyphenylenedifluorovinylene and dialkoxyphenylenevinylene units in proper ratio. The two complementary emitters are obtained separately by Stille polymerization reaction. Then, the two reaction mixtures are combined without purification in different ratios and further reacted in similar experimental conditions. A white luminescent material is obtained using 99/1 mixing ratio. OLED devices fabricated with this copolymer shows near-white emission with CIE (0.30, 0.40) and excellent stability in the range 10–200 cd/m2.

Suzuki and Stille Cross-Coupling Reactions from β-Iodovinylphosphonate: Stereoselective Access to Various Substituted Vinylphosphonates

Stereoselective synthesis of β-arylvinyl, dienyl, and en­ynylphosphonates was achieved from diethyl 2-iodovinylphosphonate via Suzuki or Stille cross-coupling reactions in good yields.

Total synthesis of (+)-ileabethoxazole via an iron-mediated Pauson-Khand [2 + 2 + 1] carbocyclization.

Studies describe the total synthesis of (+)-ileabethoxazole (1) using a Stille cross-coupling reaction of propargylic stannanes with 5-iodo-1,3-oxazoles to produce 1,1-disubstituted allenes (11). An iron-mediated [2 + 2 + 1] carbocyclization yields a novel cyclopentenone for elaboration to 1. Site-selective palladium insertion reactions allow for regiocontrolled substitutions of the heterocycle. Asymmetric copper hydride reductions are examined, and strategies for the formation of the central aromatic ring are discussed.

High open-circuit voltage organic photovoltaic cells fabricated using semiconducting copolymers consisting of bithiophene and fluorinated quinoxaline or triazole derivatives

Two new alternating copolymers consisting of bithiophene and fluorinated quinoxaline or fluorinated benzotriazole derivatives, namely, poly[{4,4′-bis(2-ethylhexyl)-2,2′-bithiophene-5,5′-diyl}-alt-{6,7-difluoro-5,5-(5,8-di-2-thienyl-2,3-bis(4-octyloxyl)phenyl) quinoxaline}] (PBT-DFDTQX) and poly[{4,4′-bis(2-ethylhexyl)-2,2′-bithiophene-5,5′-diyl}-alt-{4,7-bis(5-thiophen-2-yl)-5,6-difluoro-2-(heptadecan-9-yl)-2H-benzo[d][1,2,3]triazole}] (PBT-DFDTBTz), were synthesized by the Stille cross coupling reaction for application in organic photovoltaic cells. The optical band gaps of PBT-DFDTQX and PBT-DFDTBTz were measured to be 1.77 and 1.90eV, respectively. The synthesized polymers showed relatively deep highest occupied molecular orbital (HOMO) energy levels (−5.52eV for PBT-DFDTQX and −5.54eV for PBT-DFDTBTz) owing to the strong electron accepting nature of fluorine. The polymers were used to fabricate bulk heterojunction photovoltaic devices with [6,6]-phenyl C71-butylic acid methyl ester (PC71BM) as the electron acceptor. Devices fabricated using PBT-DFDTQX and PBT-DFDTBTz showed the maximum power conversion efficiency (PCE) of 4.01 and 4.22%, respectively, with a high open-circuit voltage of over 0.95V under AM 1.5G (100mW/cm2) conditions.

2,2'-Bi[benzo[b]thiophene]: an unexpected isolation of the benzo[b]thiophene dimer.

The crystal structure of 2,2'-bi[benzo[b]thiophene], C16H10S2, at 173 K has triclinic (P1) symmetry. It is of interest with respect to its apparent mode of synthesis, as it is a by-product of a Stille cross-coupling reaction in which it was not explictly detected by spectroscopic methods. It was upon crystal structure analysis of a specimen isolated from the mother liquor that this reaction was determined to give rise to the title compound, which is a dimer arising from the starting material. Two independent half-molecules of this dimer comprise the asymmetric unit, and the full molecules are generated via inversion centers. Both molecules in the unit cell exhibit ring disorder, and they are essentially identical because of their rigidity and planarity.

Synthesis and transformations of 5-chloro-2,2'-dipyrrins and their boron complexes, 8-chloro-BODIPYs.

Symmetric dipyrrylketones 1 a,b were synthesized in two steps from the corresponding α-free pyrroles, by reaction with thiophosgene followed by oxidative hydrolysis under basic conditions. The dipyrrylketones produced the corresponding 5-chloro-dipyrrinium salts or 5-ethoxy-dipyrrins on reaction with phosgene or Meerwein's salt, respectively. Boron complexation of the dipyrrins afforded the corresponding 8-functionalized BODIPYs (borondipyrromethenes) in high yields. The 5-chloro-dipyrrinium salts reacted with methoxide or ethoxide ions to produce monopyrrole esters, presumably via a 5,5-dialkoxy-dipyrromethane intermediate. In contrast, 8-chloro-BODIPYs underwent a variety of nucleophilic substitutions of the chloro group in the presence of alkoxide ions, Grignard reagents, and thiols. In the presence of excess alkoxide or Grignard reagent, at room temperature or above, substitution at the boron center also occurred. The 8-chloro-BODIPY was a particularly useful reagent for the preparation of 8-aryl-, 8-alkyl-, and 8-vinyl-substituted BODIPYs in very high yields, using Pd(0) -catalyzed Stille cross-coupling reactions. The X-ray structures of eleven BODIPYs and two pyrroles are presented, and the spectroscopic properties of the synthesized BODIPYs are discussed.

ChemInform Abstract: Synthesis of Thiophene 1,1‐Dioxides and Tuning Their Optoelectronic Properties.

A 2,5-bis(tributylstannyl)thiophene 1,1-dioxide was prepared from 2,5-bis(trimethylsilyl)thiophene 1,1-dioxide, bis(tributyltin) oxide, and tetrabutylammonium fluoride (TBAF). The 2,5-bis(tributylstannyl)thiophene 1,1-dioxide and a 2,5-diiodothiophene 1,1-dioxide were utilized in a series of Stille cross-coupling reactions to afford thiophene 1,1-dioxides with either electron-donating or electron-withdrawing substituents. Electron-withdrawing groups greatly facilitate the reduction of these sulfone heterocycles, and –C6H4-p-NO2 substituents produce a 510 mV shift as compared to a thiophene 1,1-dioxide with two phenyl groups.

Synthesis of Trimethylstannyl Arylboronate Compounds by Sandmeyer-Type Transformations and Their Applications in Chemoselective Cross-Coupling Reactions

A synthetic method based on Sandmeyer-type reactions to access both tin- and boron-substituted arenes from nitroaniline derivatives is described. This transformation can be applied to the synthesis of a series of functionalized trimethylstannyl arylboronates. In addition, the chemoselective reaction of the Stille and Suzuki-Miyaura cross-coupling reactions is explored, and a series of m- and p-terphenyl derivatives have been synthesized by conducting consecutive one-pot Stille and Suzuki-Miyaura cross-coupling reactions.

Tin-Functionalized Azobenzenes as Nucleophiles in Stille Cross-Coupling Reactions

The metalation of azobenzene by halogen-metal exchange typically leads to a reduction of the azo group to give hydrazine derivatives as major byproducts, instead of the desired metalated azobenzene species. In cross-coupling reactions, azobenzenes therefore usually serve as electrophiles, which greatly limits the scope of the reaction. To solve this problem, we have developed a mild and fast method to stannylate azobenzenes in high yields. This research shows that these stannylated azobenzenes can be used as nucleophilic components in Stille cross-coupling reactions with aryl bromides. The cross-coupling products were obtained in high yields ranging from 70 to 93%. With this reversal of the nucleophilic and electrophilic components, cross-coupling products are now accessible in which the aromatic rings coupled to the azobenzene bear functional groups that are sensitive to metalation.

Electrosynthesis and Characterization of the Donor-Acceptor Type Multicolored Electrochromic Materials

Two novel monomer were synthesized via Stille cross coupling reaction. Electropolymerization of the monomers gave birth to the donor-acceptor type polymers: poly{10,13-bis(2,3-dihydrothieno(3,4-b)(1,4)dioxin-5-yl) diben- zo(a,c)phenazine} (P1) and poly{10,13-bis(4-ethylthiophen-2-yl)dibenzo(a,c)phenazine} (P2). Cyclic voltammetry and UV-vis spectroscopy were used to study the electrochemical and optical properties of the polymer films. The surface mor- phologies of the polymer films were investigated by scanning electron microscopy (SEM). The slight structural modification of the two polymer films results in the variation of the optical and electronic properties. As shown in the studies, P1 film was green in the neutral state, and with the increment of the applied potentials, four different colors were observed (light green, greyish-green, grey and cadet blue). The P1 film had prominent high optical contrast (T%) of 74.8%, excellent response time of 0.6 s and good coloration efficiency (CE) of 285.8 cm 2 /C at 1600 nm. Electrochromic switching response for polymer film P1 at 470 nm, 790 nm was also monitored. The slight loss in percent transmittance contrast value at the three given wave- lengths indicated the stable ability of the polymer film of P1. The colors of polymer film P2 in the neutral and oxidized state were greyish-blue and cadet green, respectively. The optical contrast (T%) of P2 film was found to be 64.5%, the response time was 2.4 s and the coloration efficiency (CE) was 316.7 cm 2 /C at the wavelength of 1340 nm. P2 film showed high sta- bility at the wavelength of 1340 nm, but at 754 nm the stability was not satisfactory. Moreover, both of the two polymers exhibited low optical bandgap (Eg) (the Eg of P1 was 1.26 eV and the Eg of P2 was 1.54 eV). Both polymer films revealed obvious donor-acceptor behaviors, and they were not only n-dopable but also p-dopable. Keywords dibenzo(a,c)phenazine; conducting polymers; donor-acceptor behavior; electrochemical polymerization; elec- trochromism

A facile and convenient sequential homobimetallic catalytic approach towards β-methylstyrenes. A one-pot Stille cross-coupling/isomerization strategy.

An efficient one-pot synthetic approach towards β-methylstyrenes is reported. The transformation, based on sequential homobimetallic catalysis, involves a Stille cross-coupling reaction between aryl halides and allyltributylstannane, followed by an in situ palladium-catalyzed conjugative isomerization. The reaction was optimized, and the best results were obtained with 10 mol% Pd(PPh3)2Cl2, 8.0 equiv. LiCl, and 0.5 equiv. PPh3 in diglyme at 130 °C for 12 h. It was demonstrated that the reaction tolerates a wide variety of functional groups.

Palladium on nano-magnetite: a magnetically reusable catalyst in the ligand- and copper-free Sonogashira and Stille cross-coupling reactions

This paper reports on the synthesis and use of palladium on nano-magnetite as a magnetically separable catalyst for copper- and ligand-free Songashira and Stille coupling reactions. The catalyst was characterized using powder XRD, SEM, EDS and VSM techniques. This method has the advantages of high yields, simple methodology and easy work-up. Catalytic efficiency remains unaltered even after several repeated cycles.

Synthesis of squaraine-based alternated π-conjugated copolymers: from conventional cross-coupling reactions to metal-free polycondensation

Low band-gap π-conjugated copolymers based on squaraine units can be synthesized through classical Suzuki and Stille cross-coupling reactions (in blue), or through a metal-free polycondensation (in green).

Highly Conjugated Side-Chain-Substituted Benzo[1,2-b:4,5-b′]dithiophene-Based Conjugated Polymers for Use in Polymer Solar Cells

A series of novel benzo[1,2-b:4,5-b′]dithiophene (BDT)-based conjugated polymers were synthesized using a Stille cross-coupling reaction. These polymers contained dithienyl thieno[3,4-c]pyrrole-4,6-dione (DTTPD) as an acceptor. Alkylthienylenevinylene thiophene side groups were introduced into the BDT units, and the solubility, absorption spectra, energy levels, charge transport, blend film morphology, and photovoltaic properties of the resulting polymer (poly[4,8-bis{2,2′-(5-ethylhexyl)thienylenevinylenethiophene}benzo[1,2-b;3,4-b]dithiophene-2,6-diyl-alt-1,3-di(thien-5′-yl)-5-octyldodecyl[3,4-c]pyrrole-4,6-dione-2,2′-diyl], PBDTTVT-DTTPD) were investigated. In addition, an alkylthienyl-substituted BDT-based polymer (poly[4,8-bis(5-(2-ethylhexyl)thiophen-2-yl)benzo[1,2-b:4,5-b′]dithiophene-2,6-diyl-alt-1,3-di(thien-5′-yl)-5-octyldodecyl[3,4-c]pyrrole-4,6-dione-2,2′-diyl], PBDTT-DTTPD) was synthesized to compare the optoelectronic and photovoltaic properties of the polymers. The weight-averaged molecular ...

Synthesis of new acenaphtho[1,2-c]thiophene-based low bandgap polymers for organic photovoltaics

Donor–acceptor conjugated polymers, PDTTPDA and PDTTPDT, composed of new acenaphtho[1,2-c]thiophene or thiophene as electron donors and 1,3-dithien-2-yl-thieno[3,4-c]pyrrole-4,6-dione (DTTPD) as the electron acceptor were synthesized by a Stille cross-coupling reaction. These polymers combine interesting properties such as good solubility and excellent thermal stability. The weight-averaged molecular weights (Mw) of PDTTPDA and PDTTPDT were found to be 71,000 and 79,000 with polydispersity indices of 1.65 and 1.66, respectively. Photophysical studies revealed a low bandgap of 1.77eV for PDTTPDA and 1.72eV for PDTTPDT. The present study indicates that the combination of DTTPD and acenaphtho[1,2-c]thiophene building blocks can be a very effective way to lower the HOMO energy level and ultimately to enhance the Voc of polymer solar cells. The Voc reported here (up to 0.94V) is one of the highest observed in polymer:PCBM bulk heterojunction devices, and a power conversion efficiency (PCE) of up to 3.28% was observed in the PDTTPDA devices.