Article
Chemistry, Organic
Yogesh Brijwashi Sharma, Debosmita Das, Murali Mohan Guru
Summary: An efficient route for the synthesis of substituted pyrazolines has been reported using readily accessible N-propargyl hydrazones. The Cu-(II) catalyst acts as a Lewis acid to form an iminium-ion intermediate via cyclization, which upon hydrolysis affords the desired pyrazolines. This methodology has been successfully applied to the synthesis of a progesterone receptor antagonist.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Multidisciplinary
Erin Hayashi, Naoto Akiyama, Kiyomi Kakiuchi, Tsuyoshi Kawai, Tsumoru Morimoto
Summary: We developed a rhodium(I)-catalyzed asymmetric cyclohydroformylation reaction of 1,6-enynes with formaldehyde. The reaction proceeds with high enantioselectivity, producing aldehyde products with higher-order structures. This method demonstrates wide compatibility and can be successfully applied to various enynes, providing a versatile route to access chiral aldehydes.
CHEMISTRY-AN ASIAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Tomoki Yoshida, Masaya Ohta, Tomoya Emmei, Takuya Kodama, Mamoru Tobisu
Summary: The C-F bond of acyl fluorides can be cleaved and added across tethered alkenes using a cationic rhodium(I) tetrafluoroborate catalyst. This 1,2-carbofluorination reaction provides a highly efficient method for the synthesis of tertiary alkyl fluoride derivatives with a 100% atom economy. Mechanistic studies demonstrate that the concerted action of a rhodium cation and a tetrafluoroborate anion is crucial for the controlled cleavage and formation of C-F bonds in this catalytic process.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Applied
Yuya Kaieda, Kosuke Yamamoto, Masami Kuriyama, Osamu Onomura
Summary: A rhodium-catalyzed reaction has been developed to convert N-sulfonyl-1,2,3-triazoles and carboxylic esters into 2,5-disubstituted oxazole derivatives under mild reaction conditions.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Wei Yang, Maoping Pu, Xiaobin Lin, Min Chen, Yanji Song, Xiaohua Liu, Yun-Dong Wu, Xiaoming Feng
Summary: In this study, a novel method was developed for the synthesis of vinyl gamma-amino amides with high gamma-selectivity and enantioselectivity using a high-spin chiral complex catalyst. The calculation showed a spin state change from quartet cobalt(II) complex to doublet Co(II)-carbene species for Z-selective and enantioselective nucleophilic addition.
JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
(2021)
Article
Chemistry, Applied
Geetanjali S. Sontakke, Rahul K. Shukla, Chandra M. R. Volla
Summary: The Rh(I)-catalyzed decarboxylative arylation provides a straightforward platform to access substituted 2,3-allenols and 1,3-butadiene derivatives. The reaction exhibits high regioselectivity and compatibility with various functional groups, allowing the development of a library of diversely functionalized scaffolds with excellent yields. Additionally, late-stage transformation of natural products and downstream transformations highlight the wide applicability and efficacy of the protocol.
ADVANCED SYNTHESIS & CATALYSIS
(2022)
Article
Chemistry, Multidisciplinary
Mengfu Dai, Zhimin Sun, Liang-An Chen
Summary: This study reports a catalyst-controlled, tunable, and predictable regiodivergency in transforming internal aliphatic propargyl esters into diverse products, allowing facile access to regioisomers with high regio- and stereoselectivity. This method is important for the structural diversification of bioactive molecules, enabling the rapid assembly of structural analogs of pharmaceutical candidates.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Hafiza Tayyaba Shahzadi, Saman Fatima, Naseem Akhter, Meshari Alazmi, Alshammari Nawaf, Kamaleldin B. Said, Amer AlGhadhban, Abdel Moneim E. Sulieman, Rahman Shah Zaib Saleem, Ghayoor Abbas Chotana
Summary: This paper describes an iridium-catalyzed C-H borylation method for CF3-substituted pyridines, enabling the installation of boronic ester groups with steric control. The method is solvent-free and compatible with various functional groups. Although the borylated pyridines can be isolated in good yields, the alpha-borylated pyridines have a short shelf life. The boronic ester derivatives of CF3-substituted pyridines can serve as useful precursors in synthesis.
Article
Chemistry, Organic
Yuwei Zong, Yihan Tang, Gavin Chit Tsui
Summary: In this paper, we describe a highly selective Rh(I)-catalyzed defluorinative coupling of boronic acids with (E)-beta-monofluoroacrylates, which yields trisubstituted (Z)-alkene products with excellent diastereoselectivity and an inversion of double bond geometry. Experimental and computational studies demonstrate that Rh(I)-facilitated beta-F elimination is preferred over competing beta-H elimination and protodemetalation.
Article
Chemistry, Multidisciplinary
Jia Sheng Ng, Tamio Hayashi
Summary: This study revealed that the reaction of propargyl difluorides with alkylzincs catalyzed by a chiral diene/rhodium complex can yield axially chiral fluorinated allenes with high enantioselectivity (up to 99% ee). In the catalytic cycle, a key step involves the selective elimination of one of the enantiotopic fluorides at the beta-position of an alkenyl-Rh intermediate, which is generated by regioselective addition of R-3-Rh onto the triple bond of the starting difluorides.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Multidisciplinary
Junyou Zhang, Weici Xu, Ming-Hua Xu
Summary: A simple and broad-scope rhodium(I)/chiral diene catalytic system was developed for challenging asymmetric intramolecular cyclopropanation of various tri-substituted allylic diazoacetates. The low coordination state Rh-I-complex exhibited high tolerance to substitution of the allyl double bond, enabling the efficient construction of penta-substituted, fused-ring cyclopropanes with three stereogenic centers in a highly enantioselective manner. DFT calculations suggested that pi-pi stacking interactions between the aromatic rings of the chiral diene ligand and diazo substrate played a key role in controlling the reaction enantioselectivity.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Organic
Ya-Ping Wang, Xing-Ping Zhang, Ming-Sheng Xie, Hai-Ming Guo
Summary: In this study, highly enantioselective propargyl Claisen rearrangement of O-propargyl beta-ketoesters was achieved using a chiral cobalt complex as the catalyst under mild reaction conditions. A diverse range of chiral allenyl-substituted all-carbon quaternary beta-ketoesters were obtained in good yields and high enantioselectivities.
Article
Chemistry, Physical
Ryota Abe, Yuki Nagashima, Jin Tanaka, Ken Tanaka
Summary: The development of an operationally simple method for diversity-oriented fluoranthene synthesis is important in the field of organic synthesis due to the presence of the fluoranthene skeleton in natural products and fluorescent materials. In this study, substituted fluoranthenes and azafluoranthenes were synthesized at room temperature through a cationic Rh(I)/H8-BINAP complex-catalyzed [2 + 2 + 2] cycloaddition reaction using 1,8-dialkynylnaphthalenes. Both theoretical and experimental studies revealed that noncovalent interactions between the phenyl groups on the substrates and ligand stabilize the transition states, facilitating the sterically demanding reactions.
Article
Chemistry, Organic
Zhi Zhang, Jing-Tong Deng, Jia-Yi Feng, Jin-Yan Liang, Xue-Tao Xu, Jin-Bao Peng
Summary: A palladium-catalyzed annulation of o-iodo-anilines with propargyl alcohols for the synthesis of substituted quinolines has been developed. The reaction shows tolerance towards diverse functional groups under mild conditions, providing a direct access to 2,4-disubstituted quinolines from easily available starting materials. A broad range of 2,4-disubstituted quinolines were efficiently synthesized in good to excellent yields.
JOURNAL OF ORGANIC CHEMISTRY
(2023)
Article
Chemistry, Physical
Ryota Abe, Yuki Nagashima, Jin Tanaka, Ken Tanaka
Summary: The development of a simple method for diversity-oriented fluoranthene synthesis is important in organic synthesis due to the widespread occurrence of fluoranthene in natural products and fluorescent materials. In this study, we report the room temperature synthesis of substituted fluoranthenes and azafluoranthenes using a cationic Rh(I)/H-8-BINAP complex-catalyzed [2 + 2 + 2] cycloaddition. The reaction is enabled by the stabilization of intermediates by the H-8-BINAP ligand. The noncovalent interactions between the phenyl groups on both the substrates and the ligand play a crucial role in accelerating the sterically demanding reactions.
Article
Chemistry, Organic
Keisuke Fukaya, Daisuke Urabe, Masato Hiraizumi, Keiichi Noguchi, Takashi Matsumoto, Kaori Sakurai
JOURNAL OF ORGANIC CHEMISTRY
(2020)
Article
Chemistry, Organic
Hiroto Takahashi, Yusaku Honjo, Yu Shibata, Yuki Nagashima, Ken Tanaka
Summary: The dienylation of unfunctionalized arenes with 1,6-diynes, possessing aryl groups at the diyne termini, was found to proceed in the presence of an electron-deficient cyclopentadienyl rhodium(III) complex and a stoichiometric amount of silver carbonate. Experimental and theoretical mechanistic studies indicated the possible catalytic role of a (CpRh)-Rh-E(I) complex generated in situ in this reaction.
SYNTHESIS-STUTTGART
(2021)
Article
Chemistry, Multidisciplinary
Masahiro Kubo, Keiichi Noguchi, Koji Nakano
Summary: Chiral spiro pi-conjugated compounds, including a chiral benzo[b]silole-fused SBF and a pi-extended spiro polycyclic arene, have been synthesized and studied for their optical properties. These compounds exhibit circularly polarized luminescence with dissymmetry factors up to 0.76x10(-3). Experimental and theoretical analyses show that the emission of these compounds occurs from specific subunits, with slightly different structures compared to the Frank-Condon state.
Article
Biochemistry & Molecular Biology
Yosuke Inoue, Yuya Hanazono, Kentaro Noi, Akihiro Kawamoto, Masato Kimatsuka, Ryuhei Harada, Kazuki Takeda, Ryoichi Kita, Natsuki Iwamasa, Kyoka Shibata, Keiichi Noguchi, Yasuteru Shigeta, Keiichi Namba, Teru Ogura, Kunio Miki, Kyosuke Shinohara, Masafumi Yohda
Summary: A study on CtHsp104 revealed that in the presence of ADP, it assembles into a left-handed spiral filament with a hexamer of split spiral structures. Staggered and split hexameric rings were observed in cryo-EM images, and substrate addition was found to enhance the conformational change and increase the frequency of the split structure.
Article
Soil Science
Akira Takamoto, Yohey Hashimoto, Maki Asano, Keiichi Noguchi, Rota Wagai
Summary: The study investigated the distribution and chemical species of phosphorus in relation to iron and aluminum phases in two Andisols, revealing a stronger control of aluminum phases over phosphorus compared to iron phases. Phosphorus was primarily associated with aluminum, with organic and inorganic phosphorus reservoirs being important in low- to meso-density fractions in Andisols.
Article
Crystallography
Hiroaki Litsuka, Kun Li, Miyuki Kobayashi, Kikuko Lida, Keiichi Noguchi, Noriyuki Yonezawa, Akiko Okamoto
Summary: The crystal of the compound has a monoclinic structure with cell parameters a=10.3707 angstrom, b=12.0232 angstrom, c=15.7744 angstrom, and β=90.907 degrees, at a temperature of 193.15K.
ZEITSCHRIFT FUR KRISTALLOGRAPHIE-NEW CRYSTAL STRUCTURES
(2021)
Article
Chemistry, Multidisciplinary
Naofumi Naga, Keiichi Noguchi, Tomoaki Kouya, Kei Nishii
Summary: Syndiotactic-polystyrene based porous polymers were successfully obtained by polymerizations of styrene, 4-methyl styrene, or 4-tert-butyl styrene and copolymerization of St/MeSt, St/BuSt, or St/DVB using a half metallocene catalyst and methylaluminoxane. The resulting polymers exhibited lower bulk densities and a porous structure formed by networked fibers.
Article
Biochemistry & Molecular Biology
Tomonori Saotome, Sawaros Onchaiya, Subbaian Brindha, Taichi Mezaki, Satoru Unzai, Keiichi Noguchi, Jose C. Martinez, Shun-ichi Kidokoro, Yutaka Kuroda
Summary: The third PDZ domain of PSD95 has a propensity to form amyloid fibrils at high temperatures. It exhibits reversible oligomerization at high temperatures, which is unusual for a small globular protein like PDZ3. By suppressing the high-temperature oligomerization, amyloid formation can be inhibited.
Article
Biochemistry & Molecular Biology
Nina Kurokawa, Rio Midorikawa, Manami Nakamura, Keiichi Noguchi, Ken Morishima, Rintaro Inoue, Masaaki Sugiyama, Masafumi Yohda
Summary: The study examined the oligomeric structural change of CgHspB1 using sedimentation velocity analytical ultracentrifugation. It was found that at low temperatures, CgHspB1 exists as an 18-mer and is relatively unstable, partially dissociating into smaller oligomers. At elevated temperatures, the 24-mer is more stable and in dynamic equilibrium with the dissociated oligomers in the hexameric unit. Additionally, the disulfide bond between conserved cysteine residues plays a role in stabilizing the hexamers.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2021)
Article
Biochemistry & Molecular Biology
Yosuke Fukutani, Yuko Nakamura, Nonoko Muto, Shunta Miyanaga, Reina Kanemaki, Kentaro Ikegami, Keiichi Noguchi, Ikuroh Ohsawa, Hiroaki Matsunami, Masafumi Yohda
Summary: Vertebrate animals detect odors through olfactory receptors, but the studies of their odor molecule recognition mechanisms have been hindered by the difficulty in their expression in heterologous cells. However, this study found that a single amino acid substitution in conserved amino acid residues of RTP-independent ORs can significantly improve their functional expression in heterologous cells.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Polymer Science
Naofumi Naga, Shingo Okado, Yui Ohara, Keiichi Noguchi
Summary: Poly(p-phenylene alkylene)s were successfully synthesized through Kumada coupling reaction, showing moderate yields and various properties depending on the choice of alpha,omega-dibromoalkane. X-ray diffraction and FT-IR analyses revealed differences in crystal structures among the polymers. Poly(p-phenylene co-alkylenes)s were newly prepared with lower melting temperatures compared to corresponding poly(p-phenylene alkylene)s. The WAXD profiles of the co-alkylene polymers demonstrated a mix of characteristics from the individual alkylene polymers, influenced by the feed ratios of the alpha,omega-dibromoalkanes.
JOURNAL OF POLYMER RESEARCH
(2022)
Article
Biochemistry & Molecular Biology
Keisuke Uematsu, Chikara Hayasaka, Ko Takase, Keiichi Noguchi, Koji Nakano
Summary: This study reported a method to synthesize [7]helicenes and [7]helicene-like compounds from thia[7]helicene as a common starting material, including silole- and phosphole-fused compounds, cyclopentadiene-fused compounds, and aza[7]helicenes. The synthesized compounds showed unique absorption and emission properties, with slightly red-shifted absorption for silole-fused compounds and strong violet emission for cyclopentadiene-fused compounds and aza[7]helicenes. Additionally, aza[7]helicenes displayed circularly-polarized luminescence with specific dissymmetry factors.
Article
Biochemistry & Molecular Biology
Koji Nakano, Ko Takase, Keiichi Noguchi
Summary: A new family of spiro-fused polycyclic aromatic compounds containing a furan unit was designed and successfully synthesized in enantiopure form. The properties of these furan-containing compounds, including absorption and emission, were found to be different from their thiophene analogs. Additionally, all of these compounds exhibited circularly polarized luminescence.
Article
Soil Science
Shoko Uchida, Yohey Hashimoto, Akira Takamoto, Keiichi Noguchi, Wantana Klysubun, Shan-Li Wang
Summary: This study investigates the adsorption behavior of allophane and ferrihydrite in volcanic ash soils with regards to phosphate. The results show that allophane has a higher affinity for phosphate compared to ferrihydrite, especially at low to intermediate concentrations. Additionally, the study finds that precipitation of Al-phosphate occurs in allophane and allophane-ferrihydrite mixtures.
SOIL SCIENCE SOCIETY OF AMERICA JOURNAL
(2022)
Article
Chemistry, Organic
Daisuke Sato, Akira Tsubouchi, Yuichiro Watanabe, Keiichi Noguchi, Kazunori Miyamoto, Masanobu Uchiyama, Akio Saito
Summary: The activation of alkyne pi-bonds by transition metal complexes is well studied for the cycloisomerization of enynes into bicyclo[3.1.0]hexanes, enabling the introduction of carbon and oxygen functional groups. However, the cycloisomerization of enynones through the activation of carbonyl groups into bicyclo[3.1.0]hexanes has not yet been achieved. In this study, we report the aluminum halide-mediated cycloisomerization of 7-en-2-ynones into halogenated bicyclo[3.1.0]hexanes.
ORGANIC CHEMISTRY FRONTIERS
(2023)
