Professor: Toshikazu Hirao, Associate Professor: Toshiyuki Moriuchi,
Assistant Professor: Toru Amaya
Laboratory of Functional Organic Chemistry
Professor: Toshikazu Hirao, Associate Professor: Toshiyuki Moriuchi,
Assistant Professor: Toru Amaya
URL: http://www.chem.eng.osaka-u.ac.jp/~hiraken/
E-mail: hirao@chem.eng.osaka-u.ac.jp
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Efficient redox systems are created for organic synthesis and materials synthesis in our laboratory.
An efficient and highly controlled electron-transfer process is essential for the developement of selective organic reactions and functional materials. A conceptually
new redox system with highly controlled dynamic function in nano-space should be created. From these points of view, our laboratory focuses on the interdisciplinary researches summarized below, which permits the creation of redox systems for synthetic reactions, π-conjugate systems, and bio-inspired systems.
Novel Synthetic Reaction via Electron Transfer
| One-electron oxidation capability of oxovanadium(V) compounds has been demonstrated to induce synthetically useful oxidative transformations. Selective carbon-carbon bond formation occurs via ligand coupling through intermetallic interaction between vanadium species and main-group organometallics. Organoborates undergo the catalytic selective coupling under oxygen. Bio-inspired (bromoperoxidase) and environmentally harmonic vanadium-catalyzed bromination is attained in aqueous media in combination with H2O2, HBr, and KBr. Low-valent vanadiums and titaniums are employed in reductive transformations. Catalytic reactions for one-electron reduction have been achieved by using multi-component catalytic systems. Especially, the catalytic pinacol coupling provides a useful method for diastereoselective C-C bond formation.
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The hybrid systems composed of redox-active π-conjugated molecules or polymers like polyaniline and transition metals are constructed to permit the potential field reflected by both redox properties. Electronic communication between the units is considered to be possible in these systems. The structural control in the complexation has been demonstrated to give the nano-space-controlled d,π-conjugated systems. Chirality induction of the π-conjugated chain is attained by chiral complexation. These complexes are applied to efficient catalysts and electronic materials. The thus-organized conjugated palladium(II) complex is reduced to a small and well-dispersed nanoparticle.
Use of porphyrin and the corresponding zinc complex as a molecular scaffold provides a dimensionally orientated π-conjugated system bearing π-conjugated pendant groups. The structural and electronic characteristics are found to depend on the atropisomers bearing the αααα and αβαβ pendant groups. These systems are of potential in photoreflactive electron transfer. The sandwich-type π-conjugated systems are also constructed by complexation of the zinc porphyrin with a bridging ligand.  |
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Bowl-shaped π-conjugated gsumaneneh, which possesses a key partial C3v symmetric structure of fullerene, is synthesized for the first time. π-Extended π-bowls are synthesized through condensation of the sumanene trianion with aryl aldehydes. A concave-bound iron complex is synthesized by ligand exchange of a cyclopentadienyl ring of ferrocene with sumanene. The concave π-bent surface serves as a ligand to give the corresponding d,π-cojugated bowl. |
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| A combination of ferrocene as a central reverse-turn scaffold with a dipeptide unit has been demonstrated to induce antiparallel β-sheet-like, type II β-turn-like, and γ-turn-like structures depending on the chirality and sequense. This architectural control of dimensional structures utilizing minimum-sized peptide chains possessing chiral centers and hydrogen bonding sites is a versatile approach to artificial highly-ordered systems. The size-selective and chiral molecular recognition of dicarboxylic acids is realized. Crystal engineering in bioorganometallic chemistry is developed. The redox-active ferrocenes bearing a long alkylene chain is designed to be aggregated along the backbone of double helical DNA to afford redox-active (outer) and hydrophobic (inner) spheres around the double helical core. Dipeptidyl urea composed of two dipeptide chains is synthesized to form the chiral hydrogen-bonded duplex in both solid and solution states.
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References
(1) A Synthesis of Sumanene, a Fullerene Fragment, Hidehiro Sakurai, Taro Daiko, and Toshikazu Hirao, Science, 301, 1878 (2003).
(2) dl-Selective Pinacol-type Coupling Using Zinc, Chlorosilane, and Catalytic Amounts of Cp2VCl2, Toshikazu Hirao, Akiya Ogawa, Motoki Asahara, Yasuaki Muguruma, and Hidehiro Sakurai, Organic Synthesis, 81, 26-32 (2005).
(3) Conjugated Complexes with Quinonediimine Derivatives, Toshiyuki Moriuchi and Toshikazu Hirao, In Redox Systems under Nano-Space Control, Toshikazu Hirao Eds. Springer, Heidelberg, 2006, pp3-54.
(4) An Environmentally Harmonic Vanadium-Catalyzed Bromination Reaction, Toshiyuki Moriuchi, Mitsuaki Yamaguchi, Kotaro Kikushima, and Toshikazu Hirao, Tetrahedron Lett., 48 (15), 2667-2670 (2007).
(5) Template Synthesis of Polyaniline/Pd Nanoparticle and its Catalytic Application, Toru Amaya, Daisuke Saio, and Toshikazu Hirao, Terahedron Lett., 48 (15), 2729-2732 (2007).
(6) Synthesis and Characterization of π-Conjugated Bowl-Shaped π-Conjugated Molecules, Toru Amaya, Koichi Mori, Hsyueh-Liang Wu, Satoshi Ishida, Jun-ichi Nakamura, Kazuhiro Murata, and Toshikazu Hirao, Chem. Commun., (19), 1902-1904 (2007).
(7) Synthetic Transformations via Vanadium-Induced Redox Reactions, Toshikazu Hirao, In Vanadium Versatile Metal, Kenneth Kustin, Debbie C. Crans, João Costa Pessoa Eds. ACS Symposium Sereis No. 974, American Chemical Society, Washington, DC, 2007 pp 2-27.
(8) Catalytic Reductive Coupling of Carbonyl Compounds - The Pinacol Coupling Reaction and Beyond, Toshikazu Hirao, In Catalytic Reductive C-C Bond Formation, Michael J. Krische Eds. Topics in Current Chemistry, Vol. 411, Springer, Heidelberg, 2007 pp 53-75 .
(9) Redox-Switchable Conjugated Bimetallic Ruthenium(II) Complexes, Toshiyuki Moriuchi, Jun Shiori, and Toshikazu Hirao, Tetrahedron Lett., 48 (34), 5970-5972 (2007).
(10) A Concave-Bound CpFe Complex of Sumanene as a Metal in a π-Bowl, Toru Amaya, Hiroyuki Sakane, and Toshikazu Hirao, Angew. Chem. Int. Ed., 46 (44), 8376-8379 (2007).
(11) Bowl-to-bowl inversion of sumanene derivatives, Toru Amaya, Hiroyuki Sakane, Toshiko, Muneishi, and Toshikazu Hirao, Chem. Commun., (6), 765-767 (2008).
(12) Structural Characterization and Self-Association of (Arylimido)vanadium(V) Triisopropoxides, Toshiyuki Moriuchi, Kenta Ishino, Tomohiko Beppu, Masafumi Nishina, and Toshikazu Hirao, Inorg. Chem., 47(17), 7638-7643 (2008).
(13) Anisotropic Electron Transport Properties in Sumanene Microcrystals, Toru Amaya, Shu Seki, Toshiyuki Moriuchi, Kana Nakamoto, Takuto Nakata, Hiroyuki Sakane, Akinori Saeki, Seiichi Tagawa, and Toshikazu Hirao, J. Am. Chem. Soc., 131(2), 408-409 (2009).
(14) Concave-Bound Chiral Cyclopentadienyl Iron Complex of Sumanene, Hiroyuki Sakane, Toru Amaya, Toshiyuki Moriuchi, and Toshikazu Hirao, Angew. Chem. Int. Ed., 48(9), 1640-1643 (2009).
