Stereospecific Cross-Coupling between Alkenylboronates and Alkyl Halides Catalyzed by Iron–Bisphosphine Complexes

A stereospecific and high-yielding cross-coupling reaction between alkenylboron reagents and alkyl halides is described. The reaction has been achieved by using well-defined iron–bisphosphine complexes such as <b>1b</b> FeCl₂(3,5<i>-t</i>-Bu₂-SciOPP), which was recently developed by the authors′ group. Various nonactivated alkyl bromides and chlorides possessing a base/nucleophile-sensitive functional group can participate in the cross-coupling, demonstrating its utility for stereoselective synthesis of functional molecules bearing a carbon–carbon double bond

Azaboradibenzo[6]helicene: Carrier Inversion Induced by Helical Homochirality

Azaboradibenzo­[6]­helicene, a new semiconductor material possessing helical chirality, has been synthesized via a tandem bora-Friedel–Crafts-type reaction. Unprecedented carrier inversion between the racemate (displaying p-type semiconductivity) and the single enantiomer (displaying n-type semiconductivity) was observed and can be explained by changes in the molecular packing induced by helical homochirality

Azaboradibenzo[6]helicene: Carrier Inversion Induced by Helical Homochirality

Azaboradibenzo­[6]­helicene, a new semiconductor material possessing helical chirality, has been synthesized via a tandem bora-Friedel–Crafts-type reaction. Unprecedented carrier inversion between the racemate (displaying p-type semiconductivity) and the single enantiomer (displaying n-type semiconductivity) was observed and can be explained by changes in the molecular packing induced by helical homochirality

Synthesis of BN-Fused Polycyclic Aromatics via Tandem Intramolecular Electrophilic Arene Borylation

A tandem intramolecular electrophilic arene borylation reaction has been developed for the synthesis of BN-fused polycyclic aromatic compounds such as 4b-aza-12b-boradibenzo[<i>g</i>,<i>p</i>]chrysene (<b>A</b>) and 8b,11b-diaza-19b,22b-diborahexabenzo[<i>a</i>,<i>c</i>,<i>fg</i>,<i>j</i>,<i>l</i>,<i>op</i>]tetracene. These compounds adopt a twisted conformation, which results in a tight and offset face-to-face stacking array in the solid state. Time-resolved microwave conductivity measurements prove that the intrinsic hole mobility of <b>A</b> is comparable to that of rubrene, one of the most commonly used organic semiconductors, indicating that BN-substituted PAHs are potential candidates for organic electronic materials

Azaboradibenzo[6]helicene: Carrier Inversion Induced by Helical Homochirality

Azaboradibenzo­[6]­helicene, a new semiconductor material possessing helical chirality, has been synthesized via a tandem bora-Friedel–Crafts-type reaction. Unprecedented carrier inversion between the racemate (displaying p-type semiconductivity) and the single enantiomer (displaying n-type semiconductivity) was observed and can be explained by changes in the molecular packing induced by helical homochirality

Cross-Coupling of Non-activated Chloroalkanes with Aryl Grignard Reagents in the Presence of Iron/<i>N</i>-Heterocyclic Carbene Catalysts

An efficient and high-yielding cross-coupling reaction of various primary, secondary, and tertiary alkyl chlorides with aryl Grignard reagents was achieved by using catalytic amounts of <i>N</i>-heterocyclic carbene ligands and iron salts. This reaction is a simple and efficient arylation method having applicability to a wide range of industrially abundant chloroalkanes, including polychloroalkanes, which are challenging substrates under conventional cross-coupling conditions

Triplet-Energy Control of Polycyclic Aromatic Hydrocarbons by BN Replacement: Development of Ambipolar Host Materials for Phosphorescent Organic Light-Emitting Diodes

In this work, we achieved the triplet-energy control of polycyclic aromatic hydrocarbons (PAHs) by replacing the Carbon−Carbon (CC) unit with a Boron−Nitrogen (BN) unit. Time-dependent density functional theory calculations suggested that the insertion of the BN unit may cause localization of the singly occupied molecular orbitals 1 and 2 (SOMO1/SOMO2) in the triplet state, which in turn can reduce the exchange interaction and dramatically increase the high singlet–triplet excitation energy (<i>E</i>_T). The PAH containing the BN unit, 4b-aza-12b-boradibenzo­[<i>g</i>,<i>p</i>]­chrysene, showed a large <i>E</i>_T value and ambipolar carrier-transport abilities. The introduction of a phenyl substituent on 4b-aza-12b-boradibenzo­[<i>g</i>,<i>p</i>]­chrysene slightly reduced the <i>E</i>_T values and the carrier-transport abilities, but increased the glass-transition temperatures. On the basis of these findings, we successfully built phosphorescent organic light-emitting diodes using the BN compounds as host materials, which exhibit a superior performance over the device using a representative host material, 4,4′-bis­(<i>N</i>-carbazolyl)-1,1′-biphenyl, not only in terms of efficiency but also in terms of device lifetime. This study demonstrated the potential of BN-embedded polycyclic aromatics in organic electronics and showed a novel strategy to achieve triplet-energy control of aromatic compounds

Iron-Catalyzed Aromatic Amination for Nonsymmetrical Triarylamine Synthesis

Novel iron-catalyzed amination reactions of various aryl bromides have been developed for the synthesis of diaryl- and triarylamines. The key to the success of this protocol is the use of <i>in situ</i> generated magnesium amides in the presence of a lithium halide, which dramatically increases the product yield. The present method is simple and free of precious and expensive metals and ligands, thus providing a facile route to triarylamines, a recurrent core unit in organic electronic materials as well as pharmaceuticals

Iron-Catalyzed Aromatic Amination for Nonsymmetrical Triarylamine Synthesis

Novel iron-catalyzed amination reactions of various aryl bromides have been developed for the synthesis of diaryl- and triarylamines. The key to the success of this protocol is the use of <i>in situ</i> generated magnesium amides in the presence of a lithium halide, which dramatically increases the product yield. The present method is simple and free of precious and expensive metals and ligands, thus providing a facile route to triarylamines, a recurrent core unit in organic electronic materials as well as pharmaceuticals

Robust Surface Plasmon Resonance Chips for Repetitive and Accurate Analysis of Lignin–Peptide Interactions

We have developed novel surface plasmon resonance (SPR) sensor chips whose surfaces bear newly synthesized functional self-assembled monolayer (SAM) anchoring lignin through covalent chemical bonds. The SPR sensor chips are remarkably robust and suitable for repetitive and accurate measurement of noncovalent lignin–peptide interactions, which is of significant interest in the chemical or biochemical conversion of renewable woody biomass to valuable chemical feedstocks. The lignin-anchored SAMs were prepared for the first time by click chemistry based on an azide–alkyne Huisgen cycloaddition: mixed SAMs are fabricated on gold thin film using a mixture of alkynyl and methyl thioalkyloligo­(ethylene oxide) disulfides and then reacted with azidated milled wood lignins to furnish the functional SAMs anchoring lignins covalently. The resulting SAMs were characterized using infrared reflection–absorption, Raman, and X-ray photoelectron spectroscopies to confirm covalent immobilization of the lignins to the SAMs via triazole linkages and also to reveal that the SAM formation induces a helical conformation of the ethylene oxide chains. Further, SPR measurements of the noncovalent lignin–peptide interactions using lignin-binding peptides have demonstrated high reproducibility and durability of the prepared lignin-anchored sensor chips