9.Total Synthesis of (-)-Agelastatin A
Takehiko Yoshimitsu, Tatsunori Ino, Tetsuaki Tanaka Org. Lett., 10, 5457-5460 (2008).
Abstract:A stereospecific route to agelastatin A has been established from
a known chiral 1-hydroxy-4-aminocyclopentene derivative. Requisite nitrogen functionalities
of the agelastatin core have been successfully installed by thermal intramolecular aziridination
of azidoformate and subsequent regioselective azidation with NaN3, leading to net stereospecific
vicinal trans-diamination of the double bond. The present synthesis also demonstrates two new
protocols for the preparation of an imidazolidinone hemiaminal motif from an oxazolidinone
intermediate, which comprise sequential N-tert-butoxy carbonylation, urea formation, hydrolysis,
and oxidative cyclization; and direct aminolysis and subsequent oxidative cyclization.
8.Samarium(II)-Mediated Spirocyclization by Intramolecular Aryl Radical Addition onto an Aromatic Ring
Hiroki Iwasaki, Toru Eguchi, Nozomi Tsutsui, Hiroaki Ohno, Tetsuaki Tanaka J. Org. Chem., 73, 7145-7152 (2008).
Abstract: Samarium(II)-mediated spirocyclization by intramol. addn. of aryl
radicals onto an arom. ring was achieved by the reaction of
N-(2-iodophenyl)-N-alkylbenzamides with SmI2 in the presence of HMPA,
yielding spirocyclic indolin-2-one derivs., e.g., I. The ether
congeners afford spirocyclic benzofuran derivs., e.g., II, in moderate
yields by aryl radical addn. onto a benzene ring without having an
electron-withdrawing group. The reaction with other aryl groups such as
naphthalene and indole rings is also described.
7. Synthesis of C4-fluorinated solamins, and their growth inhibitory activity against human cancer cell lines
Naoto Kojima, Hiromi Hayashi, Satoshi Suzuki, Hiroaki Tominaga, Naoyoshi Maezaki, Tetsuaki Tanaka, and Takao Yamori Bioorg. Med. Chem. Lett., 18, 6451-6453 (2008).
Abstract: C4-Fluorinated analogues of solamin, an antitumor acetogenin,
were synthesized and investigated for their growth inhibitory activity against 39 tumor cell lines.
6. Polyamines stabilize left-handed Z-DNA: Using X-ray crystallographic analysis, we have found a new type of polyamine (PA) that stabilizes left-handed Z-DNA
Hirofumi Ohishi, Mamiko Odoko, Kazimierz Grzeskowiak, Yoichi Hiyama, Koji Tsukamoto, Naoyoshi Maezaki, Toshimasa Ishida, Tetsuaki Tanaka, Nobuo Okabe, Keiichi Fukuyama, Da-Yang Zhou and Kazuhiko Nakatani Biochem. Biophys. Res. Commun., 366, 275-280 (2008).
Abstract:There are many great reports of polyamine stabilization of the Z-DNA by bridge conformation between neighboring,
symmetry-related Z-DNA in the packing of crystals. However, polyamine binding to the minor groove of Z-DNA and stabilizing the Z-DNA structure
has been rarely reported. We proved that the synthesized polyamines bind to the minor groove of Z-DNA and stabilize the conformation
under various conditions, by X-ray crystallographic study. These polyamines consist of a polyamine nano wire structure. The modes of the polyamine
interaction were changed under different conditions. It is the first example that the crystals consisted of metal free structure.
This finding provides a basis for clarifying B-Z transition mechanics.
5. Synthesis of (±)-aphanorphine: a new approach to tricyclic 3-benzazepine scaffold using two radical C-C bond forming reactions
Takehiko Yoshimitsu, Chie Atsumi, Emiko Iimori, Hiroto Nagaoka, Tetsuaki Tanaka Tetrahedron Lett., 49, 4473-4475 (2008).
Abstract: An expeditious approach to (±)-aphanorphine has been established using readily available starting
materials. The present synthesis relies on the direct assembly between N-methylpyrrolidone (NMP) and 2-bromoanisaldehyde,
which takes place through Et3B/air-mediated transformation of the a-nitrogen-substituted sp3C-H bond, and features a new
design concept for the synthesis of the tricyclic 3-benzazepine skeleton.
4. Palladium-catalysed biscyclisation of allenic bromoalkenes through a zipper-mode cascade
Akinori Okano, Tsuyoshi Mizutani, Shinya Oishi, Tetsuaki Tanaka, Hiroaki Ohno and Nobutaka Fujii Chem. Commun., 3534-3536 (2008).
3. Direct Construction of Bicyclic Heterocycles by Palladium-Catalyzed Domino Cyclization of Propargyl Bromides
Hiroaki Ohno, Akinori Okano, Shohei Kosaka, Koji Tsukamoto, Miyo Ohata, Kotaro Ishihara, Hatsuo Maeda, Tetsuaki Tanaka, and Nobutaka Fujii. Org. Lett., 10, 1171-1174 (2008).
2. Synthesis of hybrid acetogenins, α,β-unsaturated-γ-lactone-free nitrogen-containing heterocyclic analogues, and their cytotoxicity against human cancer cell lines
Naoto Kojima, Tetsuya Fushimi, Naoyoshi Maezaki, Tetsuaki Tanaka, Takao Yamori, Bioorg. Med. Chem. Lett., 18, 1637-1641 (2008).
Abstract: A series of nitrogen-containing heterocyclic analogues of solamin, a natural mono-THF acetogenin,
have been synthesized and investigated for their cytotoxicity against 39 tumor cell lines.
1. New Free Radical-Besed Method for Producing Heteroatom-Containing Molecular Skeletons
Takehiko Yoshimitsu, Tetsuaki Tanaka, Manufacturing & Technology , 60, 99-101 (2008).