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Mn-catalyzed hydroarylation polyaddition of 1-(2-pyrimidinyl)pyrrole (1a) with aromatic diynes is investigated. The use of commercially available MnBr(CO) 5 as a precatalyst under the optimized reaction conditions resulted in a site- and regioselective hydroarylation polyaddition, affording the corresponding poly(arylenevinylene)s (PAVs) with excellent vinylene selectivity. The reaction protocol eliminates the production of stoichiometric amounts of byproducts from the monomers. The nonstoichiometric polyaddition of an excess amount of 1a with aromatic diynes is also demonstrated. The 2-pyrimidinyl substituent promoted the intramolecular transfer of the Mn catalyst walking through the 1a moiety., (© 2024 Wiley‐VCH GmbH.)

This study focuses on the development of regiospecific hydroarylation polyaddition of naphthalene- and carbazole-based monomers with diynes under mild reaction conditions at room temperature. A 1-pyrazole substituent serves as an appropriate directing group for a Co-catalyst to efficiently activate the C-H bonds of generally inactive six-membered aromatic hydrocarbons. The 1-pyrazole groups in 2,6-di(1-pyrazolyl)naphthalene adopt planar conformations and act as directing groups, resulting in a smooth hydroarylation reaction. In contrast, the reaction with 1,5-di(1-pyrazolyl)naphthalene do not proceed. The polyaddition reaction of 2,6-di(1-pyrazolyl)naphthalene selectively proceeds at 3,7-positions under mild reaction conditions at 30 °C, and yields corresponding poly(arylenevinylene) (PAV) with high molecular weight. This molecular design is also applicable to the hydroarylation polyaddition of carbazole; the polyaddition reaction of 9-(2-ethylhexyl)-3,6-di(1-pyrazolyl)carbazole selectively occurred at 2,7-positions. The optical and electronic properties of the synthesized compounds are evaluated. The obtained PAVs serve as an emitting material in organic light-emitting diode (OLED). This study aims to develop a Co-catalyzed hydroarylation polyaddition via C-H activation of generally inactive polyaromatic hydrocarbons (PAHs) under mild conditions., (© 2024 Wiley‐VCH GmbH.)

Nonstoichiometric direct arylation polycondensation of 2,2',3,3',5,5',6,6'-octafluorobiphenyl with excess of 2,7-diiodo-9,9-dioctyl-9H-fluorene is demonstrated. Pd/Ag dual-catalyst system under water/2-methyltetrahydrofuran biphasic conditions enables direct arylation under mild conditions and promotes the intramolecular transfer of a Pd catalyst walking through the fluorene moiety. The nonstoichiometric direct arylation polycondensation under the optimized reaction conditions produces the corresponding π-conjugated polymer with a high molecular weight and terminal octafluorobiphenyl units at both ends., (© 2023 Wiley-VCH GmbH.)

Polyaddition via the Co-catalyzed hydroarylation of 1-(2-pyrimidinyl)pyrrole with aromatic diynes affords poly(arylenevinylene)s under mild conditions. This reaction avoids production of stoichiometric amounts of by-products. Although structural analysis of the obtained polymers reveals the presence of 1,1-vinylidene unit, switching the counter anion of the Co catalyst and steric hindrance of the diyne monomers improves the regioselectivity of the polymers. When a catalyst with bulky counter anions is used for the reaction of less hindered diyne monomers, 1,2-vinylene linkages are formed dominantly over 1,1-vinylidene linkages (93:7). The effect of the regioselectivity of the polymer on the optical and semiconducting properties is also evaluated., (© 2021 Wiley-VCH GmbH.)

Conjugated polymers have immense potential for their use as semiconducting materials in organic optoelectronic devices. The improvement of synthetic methods for conjugated polymers is important for the practical application of conjugated polymers. For mass production, synthetic methods must be developed by considering the concerns regarding cost and environment. Reduction in the number of synthetic steps is an efficient approach to address these concerns. The utilization of direct CH functionalization is a reasonable strategy in monomer and polymer syntheses, because the prefunctionalization steps for CC bond formation can be eliminated. This review summarizes the recent developments in the efficient syntheses of conjugated polymers as well as their monomers via direct arylation (CH/CX coupling) and cross-dehydrogenative coupling (CH/CH coupling) reactions., (© 2020 Wiley-VCH GmbH.)

In this study, π-conjugated poly(arylenevinylene)s are synthesized via the Pd-catalyzed dehydrogenative direct alkenylation of polyfluoroarenes with diethenyl aromatic monomer. The introduction of a fluoro group promotes the cross-coupling reaction, and the formation of the undesired homocoupling byproduct is minimized by optimizing the reaction conditions. The polycondensation reactions lead to the formation of poly(arylenevinylene)s with a well-defined trans-configuration. The obtained polymers are evaluated as emitting materials for organic light-emitting diodes., (© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Polycondensation of 1-(2-pyrimidinyl)pyrrole with 2,7-dibromo-9,9-dioctylfluorene via Ru-catalyzed direct arylation gives the corresponding conjugated polymer with a molecular weight of 19 800 in 86% yield. The introduction of directing group, 2-pyrimidinyl substituent, into the pyrrole monomer induces ortho-metalation and provides the site-selective direct arylation polycondensation at the α-position of pyrrole unit without the protection of β-position. The removal of 2-pyrimidinyl substituent on the pyrrole unit proceeds efficiently and results in the enhancement of coplanarity along the main chain of the polymer., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

The polycondensation reaction of 3,4-ethylenedioxythiophene with 2,7-dibromo-9,9-dioctylfluorene via Pd-catalyzed direct arylation gives poly[(3,4-ethylenedioxythiophene-2,5-diyl)-(9,9-dioctylfluorene-2,7-diyl)]. The reaction conditions are optimized in terms of the Pd precatalysts, reaction time, and carboxylic acid additives. The combination of 1 mol% Pd(OAc)(2) and 1-adamantanecarboxylic acid as an additive is the optimized catalytic system, and it yields the corresponding polymer with a molecular weight of 39,400 in 89% yield. The polycondensation reaction, followed by an end-capping reaction, effectively provides a linear polymer without Br terminals., (Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)

Regioregulated poly(aminopyridine)s were synthesized by a Pd-catalyzed CN coupling reaction. The polymerization using Pd(0) and a bulky monodentate phosphine ligand distinctively produced the para-linked and meta-linked poly(aminopyridine)s, without the need for a protection process. The regioregularity of the polymer was confirmed by (1) H NMR spectroscopy. Model reactions were studied to evaluate the possibility of crosslinkage in the polymer. A large difference in reactivity was observed between 5-amino-2-bromopyridine and 2-amino-5-bromopyridine, which should have afforded same product. Density functional theory (DFT) calculations indicated that electron densities of the Br-bound carbon atom and the pyridine-nitrogen atom determine the reactivity of the monomers., (Copyright © 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)