HETEROCYCLES
An International Journal for Reviews and Communications in Heterocyclic ChemistryWeb Edition ISSN: 1881-0942
Published online by The Japan Institute of Heterocyclic Chemistry
Special Issue
Isao Kuwajima's Special Issues, Vol. 90, No. 1, 2015
Published online: 7th May, 2014
■ Bisindole Alkaloids Condensed with a Cyclopropane Ring, Part 2. Cyclopropano-vinorelbine and Its Derivatives
Péter Keglevich, László Hazai, Zsófia Dubrovay, Zsuzsanna Sánta, Miklós Dékány, Csaba Szántay, Jr., György Kalaus, and Csaba Szántay*
*Department of Organic Chemistry and Technology, Budapest University of Technology and Economics, H-1111 Budapest, Szt. Gellért tér 4, Hungary
Abstract
Vinorelbine condensed with a cyclopropane ring in the position 14 and 15 of the vindoline monomer part was synthesized and was found to have excellent antitumor activity. Further derivatives of cyclopropano-vinorelbine were prepared, the vincristine-like derivative, the N1-formyl-cyclopropano-vinorelbine, and the hydrated vinorelbine analogue, i.e. 5’-desmethylene-cyclopropano-vinblastine.
Published online: 24th June, 2014
■ Synthetic Studies on Saframycin Anibiotics: An Improved Synthesis of Tricyclic Lactam Intermediate and Construction of the Core Ring System of Saframycin A
Shinya Kimura, Shintaro Kawai, Masayuki Azuma, Yoshifumi Umehara, Yu-ichi Koizumi, Masashi Yokoya, and Naoki Saito*
*Department of Medicinal Chemistry, Pharmaceutical Chemistry, Meiji Pharmaceutical University, 2-522-1 Noshio, Kiyose, Tokyo 204-8588, Japan
Abstract
An improved synthesis of the tricyclic lactam intermediate of saframycin antibiotics and the construction of the core ring system having a cyano group at C-21 position were presented.1 The stereochemistry of several key intermediates was determined by X-ray crystallographic analysis.
Published online: 19th June, 2014
■ Group-Assisted Purification (GAP) for Protection of Amino Acids Using N-Phosphonyl Functional Groups
Guanghui An, Cole Seifert, Hao Sun, Yi Pan, and Guigen Li*
*Department of Chemistry & Biochemistry, Texas Tech University, Lubbock, TX 79409-1061, U.S.A.
Abstract
Various phosphonyl halides have been synthesized and utilized as protection groups for amino acids. The protection synthesis was performed via GAP (Group-Assisted Purification) procedure under convenient conditions without the use of column chromatography and recrystallization. The synthesis can be carried out on applicational scales with excellent yields (82% - 98%). The phosphonyl protection of amino acids would provide a new greener tool for GAP peptide synthesis.
Published online: 10th June, 2014
■ Design and Synthesis of Conformationally Constrained Bicyclo[2.2.2]octane-Based Unusual α-Amino Acid Derivatives via the Diels–Alder Reaction
Sambasivarao Kotha* and Milind Meshram
*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India
Abstract
We report a simple synthetic approach to various conformationally constrained bicyclic α-amino acid derivatives using the Diels−Alder reaction as a key step. Moreover, we have investigated the reactivity pattern of various anthracene derivatives in relation to the Diels−Alder chemistry.
Published online: 12th June, 2014
■ Synthesis and Evaluations of GLP-1 Secretion and Anti-Diabetic Effect in KKAy Mice of New Tricyclic Compounds
Daisuke Minehira, Daisuke Takeda, Shota Miyawaki, Atsushi Kato, Isao Adachi,* Akira Miyazaki, Ryuta Miyatake, Masahito Umezaki, Kyoko Miura, Yoshiro Kitahara, Kenji Sugimoto, Yuji Matsuya, and Naoki Toyooka*
*Graduate School of Science and Technology, Toyama University, Gofuku 3190, Toyama 930-8555, Japan
Abstract
Glucagon-like peptide-1 (GLP-1), which belongs to the family of incretins, plays important role for the regulation of plasma glucose. Accordingly, GLP-1-based therapies for type 2 diabetes have recognized as one of the most interesting target. In this study, we have found the new tricyclic compounds having strong GLP-1 secretion from human intestinal L cells, and anti-diabetic properties in spontaneously obese and diabetic KKAy mice. The most potent compound 5ka was obtained as the unexpected product, and we would like to report the details of the synthesis, structure elucidations, pharmacological activities on secretion of GLP-1, and anti-diabetic effects using diabetic KKAy mice.
Published online: 13th June, 2014
■ Stereoselective Approach toward Ophiodilactones Based on an Intramolecular [2 + 2] Cycloaddition Reaction
Takaaki Matsubara, Jun Ishihara, and Susumi Hatakeyama*
*Graduate School of Biomedical Sciences, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
The highly enantio- and diastereoselective synthesis of a promising precursor of ophiodilactones A and B, tetrameric phenylpropanoids isolated from the ophiuroid Ophiocoma scolopendrina, is described. The synthesis involves an organocatalytic asymmetric Michael reaction, intramolecular [2 + 2] cycloaddition of a ketene to an alkene, Baeyer-Villiger oxidation, and construction of the C2 quaternary center as major transformations.
Published online: 30th June, 2014
■ 2-Debromonagelamide U, 2-Debromomukanadin G, and 2-Debromonagelamide P from Marine Sponge Agelas sp.
Kenta Nakamura, Taishi Kusama, Naonobu Tanaka, Kanae Sakai, Tohru Gonoi, Jane Fromont, and Jun'ichi Kobayashi*
*Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
Two new monomeric bromopyrrole alkaloids (1 and 2) and one new dimeric bromopyrrole alkaloid (3) were isolated from an Okinawan marine sponge Agelas sp. Spectroscopic analyses of these compounds revealed the structures of 1–3 to be 2-debromonagelamide U, 2-debromomukanadin G, and 2-debromonagelamide P, respectively. Antimicrobial activity of 1–3 was evaluated.
Published online: 23rd July, 2014
■ Base Pair Recognition Ability of 2-(Methylamino)pyrimidin-4-yl Nucleobase in Parallel Triplex DNA
Yoshiyuki Hari,* Satoshi Kashima, Yuya Matsuda, Akihiro Sakata, Ryutaro Takamine, Shin Ijitsu, and Satoshi Obika*
*Graduate School of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 560-0871, Japan
Abstract
A phosphoramidite bearing a 2-(methylamino)pyrimidin-4-yl nucleobase was synthesized and the modified oligonucleotide (triplex-forming oligonucleotide, TFO) was successfully obtained using the phosphoramidite on an automated DNA synthesizer. UV-melting experiment of triplex DNA between the synthesized TFO and duplex DNA targets indicated that the 2-aminopyrimidin-4-yl unit in TFO could be a useful core structure for recognition of a TA base pair in duplex DNA.
Published online: 4th August, 2014
■ Total Synthesis of Marine Sesquiterpenoid Sinularianin B and 8-epi-Sinularianin B
Koichiro Ota and Hiroaki Miyaoka*
*School of Pharmacy, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
The enantioselective total synthesis of marine sesquiterpenoid sinularianin B, isolated from the Formosan soft coral Sinularia sp., has been accomplished in 16 steps based on a highly concise synthetic strategy. The synthesis features two highly stereoselective sulfone-mediated reactions, including a key tandem intermolecular−intramolecular alkylation developed in our laboratory, and a palladium-catalyzed desulfonylation of an allyl sulfone through π-allyl palladium complex formation.
Published online: 19th August, 2014
■ Synthesis of Bicyclic Dioxetanes Bearing a Hydroxyphenanthrene or Hydroxy[4]helicene Moiety and Their Base-Induced Chemiluminescent Decomposition
Yohei Koyama, Nobuko Watanabe, Hisako K. Ijuin, and Masakatsu Matsumoto*
*Department of Chemistry, Faculty of Science, Kanagawa University, 2946 Tsuchiya, Hiratsuka 259-1293, Japan
Abstract
Six bicyclic dioxetanes bearing a 1-hydroxyphenanthren-3-yl 2-iv, 3-hydroxyphenanthren-1-yl 2-ov, 4-hydroxyphenanthren-2-yl 2-oh, 2-hydroxyphenanthren-4-yl 2-ih, 4-hydroxy[4]helicen-2-yl 3-iv and 2-hydroxy[4]helicen-4-yl group 3-ov were synthesized and their base-induced chemiluminescent decomposition was investigated in a TBAF (tetrabutylammonium fluoride) / MeCN system. For dioxetanes in the iv-series 2-iv and 3-iv including α-naphthol-analog 17a and those in the ov-series 2-ov and 3-ov including β-naphthol-analog 17b, we investigated how the chemiluminescence properties changed with an increase in the number of fused benzene rings of a hydroxyarene moiety attached to a dioxetane ring. The results showed that a) maximum wavelength of chemiluminescence λmaxCL tended to shift to a longer wavelength region as the number of fused benzene rings increased, b) the kCTID values for the iv-series were >1000 times larger than those for the ov-series regardless of the number of fused benzene rings, and c) a dioxetane in the iv-series tended to have a higher singlet-chemiexcitation efficiency ΦS than the corresponding dioxetane in the ov-series. This tendency could be explained by the “syn/anti” rotational isomerism of an aromatic electron donor, where an anti-rotamer gives ΦS far more effectively than a syn-rotamer.
Published online: 20th August, 2014
■ Synthesis and Biological Evaluation of C-Aromataxane Derivatives as P-Glycoprotein-Mediated Multi Drug Resistance Reversal Agents
Takayuki Doi,* Naoko Yamaguchi, Kosuke Ohsawa, Kazuoki Nakai, Masahito Yoshida, Kazuhiro Satake, Yuji Mitani, Hiroshi Nakagawa, Takashi Takahashi, and Toshihisa Ishikawa
*Graduate School of Pharmaceutical Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan
Abstract
Synthesis and evaluation of C-aromataxane derivatives as P-glycoprotein-mediated MDR reversal agents have been demonstrated. Several derivatives possessing N-benzoylphenylisoserine at the C2 or C14 position of the template 2a were readily synthesized and were evaluated their affinity for P-glycoprotein. Most of the synthesized derivatives exhibited much lower cytotoxicity in both KB-3-1 cells and MDR KB-G2-cells than paclitaxel (1), and it should be noted that the compound (14R)-5a exhibited high Km and Vmax/Km values, and cytotoxicity of paclitaxel (1) in MDR KB-G2 cells was significantly recovered (98% reduction, IC50 30 nM) in the presence of 5a (5.0 μM). The structural features such as endo-cage conformation and the stereochemistry at the C14 position is crucial to exhibit an excellent affinity for P-glycoprotein.
Published online: 8th August, 2014
■ Perylene-Based, Bis(terpyridine)-Ru(II) Complexes: Synthesis, Electrochemical and Photovoltaic Properties
Hany El-Batal, Juan Manríquez Rocha, Perla F. Méndez, Luis A. Godínez, Kai Guo, Xiaopeng Li, Xiaocun Lu, Chrys Wesdemiotis, Charles N. Moorefield, and George R. Newkome*
*Departments of Polymer Science and Chemistry, The University of Akron, Akron, OH 44325-4717, U.S.A.
Abstract
Perylene-based, terpyridine-Ru(II) complexes are synthesized and their electrochemical and photoelectrochemical properties are studied; their fabrication into dye-sensitized solar cells are described (DSSCs) and their resultant photovoltaic properties are evaluated.
Published online: 7th August, 2014
■ A New Class of Structurally Simple and Highly Emissive Fluorophores with a Pyridine–Acetylene–Phenol Conjugate
Yuki Ohishi, Hajime Abe,* and Masahiko Inouye*
*Department of Chemical Biology, Graduate School of Pharmaceutical Sciences, University of Toyama, Sugitani 2630, Toyama, 930-0194, Japan
Abstract
A model compound for pyridine–acetylene–phenol conjugates was prepared, and its hydrogen-bonding and spectroscopic properties were studied. Pyridine and phenol moieties worked as a hydrogen-bonding acceptor and an donor, respectively, so that the conjugate model efficiently bound to MeOH. The absorption and fluorescence spectra showed remarkable additive effects against acid and base, illustrating the application of the conjugates to recognition-sensitive fluorophores.
Published online: 6th August, 2014
■ Thermal [2+2]-Cycloadditions of Diphenylketene with Aryl- and Hetaryl-Substituted Thioketones
Grzegorz Mlostoń,* Katarzyna Urbaniak, Anna Szychowska, Anthony Linden, and Heinz Heimgartner*
*Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
Abstract
The reaction of diphenylketene (1) with aryl- and hetaryl-substituted thioketones (2) gave the corresponding 3,3,4,4-tetraarylthietan-2-ones (3) in good yields. Remarkably, the reactions with bis-hetaryl-substituted thioketones occurred significantly faster compared with those involving the bis-aryl-substituted thioketones. The structure of compound 3c has been established by X-ray crystallography.
Published online: 22nd July, 2014
■ Mn(III)-Based Oxidative Cyclization of N-Aryl-3-oxobutanamides. Facile Synthesis and Transformation of Substituted Oxindoles
Nobutaka Kikue, Tetsuya Takahashi, and Hiroshi Nishino*
*Department of Chemistry, Graduate School of Science and Technology, Kumamoto University, Kurokami 2-39-1, Chûou-Ku, Kumamoto 860-8555, Japan
Abstract
The oxidation of 3-oxo-N-phenylbutanamides 1 with manganese(III) acetate in ethanol afforded dimeric 3,3'-biindoline-2,2'-dione derivatives 3–5. A similar reaction of N,2-disubstituted N-aryl-3-oxobutanamides 6 in acetic acid produced 3-acetylindolin-2-ones 7 bearing various substituents in good to excellent yields. The acetylindolinones 7 were easily deacetylated by treatment using neutral alumina in diethyl ether. Both the acetylindolinones 7 and deacetylated indolinones 8 were transformed by reduction into the substituted 1H-indoles.
Published online: 4th August, 2014
■ Synthesis of Model Compounds Related to Linear β-D-(1→6)-Galactosyl Side-Chains of Polysaccharides from Astragalus mongholicus Bunge
Noriyasu Hada, Ryo Shimura, Kyoko Hakamata, Hiroaki Kiyohara, Haruki Yamada, Tadahiro Takeda, and Fumiyuki Kiuchi*
*Faculty of Pharmacy, Keio University, 1-5-30 Shiba-Kouen, Minato-ku, Tokyo, Japan
Abstract
Stereocontrolled efficient syntheses of β-(1→6)-linked di-, tetra- and octa-galactans as model compounds of arabino-3,6-galactans isolated from Astragalus mongholicus are described. The syntheses consisted of simple glycosylation cycles: an acceptor and a donor prepared from a common compound were coupled, and the glycosylation product was converted to the acceptor and donor of the next glycosylation.
Published online: 24th July, 2014
■ Studies toward the Total Synthesis of Amphidinolide N: Stereocontrolled Synthesis of the C13–C29 Segment
Makoto Sasaki,* Yuki Kawashima, and Haruhiko Fuwa
*Laboratory of Biostructural Chemistry, Graduate School of Life Sciences, Tohoku University, 2-1-1, Katahira, Aoba-ku, Sendai, 980-8577, Japan
Abstract
A stereocontrolled synthesis of the C13–C29 segment of amphidinolide N, a marine macrolide natural product that is extremely potent cytotoxic, is described.
Published online: 26th March, 2014
■ A New Indole Alkaloid from Voacanga grandifolia
Azusa Haseo, Alfarius Eko Nugroho, Yusuke Hirasawa, Toshio Kaneda, Osamu Shirota, Abdul Rahman, Idha Kusumawati, Noor Cholies Zaini, and Hiroshi Morita*
*Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan
Abstract
A new bisindole alkaloid, voacalgine F (1), has been isolated from the bark of Indonesian Voacanga grandifollia (Miq.) Rolfe. Its structure was elucidated on the basis of 1D and 2D-NMR data analysis.
Published online: 4th April, 2014
■ Novel Intramolecular Cyclization-Skeletal Reorganization of 2-Arylthiazoles under Photoirradiation
Noriyoshi Arai,* Moe Mizota, and Takeshi Ohkuma*
*Division of Chemical Process Engineering, Graduate School of Engineering, Hokkaido University, Kita 13 Nishi 8, Kita-ku, Sapporo, Hokkaido 060-8628, Japan
Abstract
Photoirradiation of 2-arylthiazoles derivatives linked with an alkene moiety through a three-atom spacer was investigated. The main products were unexpected tetrahydrofuran-fused thiazepine derivatives with concomitant formation of [2+2] cycloaddition products and regioisomeric thiazoles. The product distribution was little influenced by the reaction conditions and substituents of the substrates.
Published online: 3rd April, 2014
■ Studies on the Effect of N-Heterocyclic Carbene as a Ligand for Nickel(II)-Catalyzed Polymerization of Thiophenes
Atsunori Mori,* Makoto Fujio, and Shunsuke Tamba
*Chemical Science & Technology, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
Effect of N-heterocyclic carbene (NHC) ligand in the nickel-catalyzed polythiophene synthesis is studied. One-pot protocol to form nickel-NHC ligand with the corresponding HCl salt of NHC and Ni(acac)2 in the presence of a base and following deprotonation and polymerization smoothly affords poly(3-hexylthiophen-2,5-diyl) (2a). Among NHC ligands examined, imidazolidine derived NHC bearing 2,6-diisopropylphenyl group as an N-substituent is found to be the optimum ligand.
Published online: 2nd April, 2014
■ Synthesis of Unprotected CH2-Skipped Piperazine-Pyridine Alternating Cycles with Azide End-Group
Andi Kipper, Indrek Kalvet, Kaido Tämm, Lauri Sikk, Peeter Burk, Kuldar Kõiv, and Uno Mäeorg*
*Institute of Chemistry, University of Tartu, Ravila 14a, Tartu 50411, Estonia
Abstract
This work describes synthesis of CH2-skipped alternating piperazine-pyridine cycles with azide end-group starting from piperazine, 1-methylpiperazine and pyridine-2,6-dicarboxylic acid. This compound can be used to enhance binding efficiency by shielding repulsion between negatively charged phosphate groups in DNA-oligonucleotide hybridization techniques.
Published online: 4th April, 2014
■ Phenol and Aniline Oxidative Coupling with Alkenes by Using Hypervalent Iodine Dimer for the Rapid Access to Dihydrobenzofurans and Indolines
Toshifumi Dohi, Yosuke Toyoda, Tomofumi Nakae, Daichi Koseki, Hiroko Kubo, Tohru Kamitanaka, and Yasuyuki Kita*
*College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan
Abstract
A highly reactive hypervalent iodine dimer, [Ph(CF3COO)I]-O-[I(OCOCF3)Ph], is utilized as successful promoter in the oxidative phenolic coupling with styrenes leading to 2-aryldihydrobenzofurans. The extensions of the substrates in this study have led to the development of a new expeditious construction of the pyrroloindoline structure from aniline and enamide derivatives.
Published online: 21st May, 2014
■ Diversity Oriented Approach to Oxepine Derivatives: Further Expansion via Diels‒Alder Reaction
Sambasivarao Kotha* and Rashid Ali
*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India
Abstract
Oxepine derivatives have been assembled via Diels‒Alder (DA) reaction as a key step and the latent dienes suitable for the DA reaction have been generated in situ from the sultine derivatives, which in turn were achieved by using commercially available rongalite. The “drug like” molecules assembled here may find useful applications in medicinal as well as bioorganic chemistry.
Published online: 3rd June, 2014
■ N-(2,3,4,5,6-Pentafluorophenyl)maleimide as a Powerful Dienophile in Dearomatizing Diels-Alder Reactions
Koichi Hagiwara, Masafumi Iwatsu, Daisuke Urabe, and Masayuki Inoue*
*Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Abstract
Here we demonstrate that N-(2,3,4,5,6-pentafluorophenyl)maleimide effectively promotes dearomatizing Diels-Alder reactions of 2,5-dimethylbenzene-1,4-diol and naphthalen-2-ol derivatives. The present reactions successfully converted the sp2-rich components to the desired products with multiple sp3-carbons in a single step. The adduct was further derivatized into the intermediate for our synthesis of 9-demethyl-10,15-dideoxyryanodol, an analogue of a sp3-rich natural product, in two steps.
Published online: 9th June, 2014
■ Pd-Catalyzed Intramolecular Oxidative Coupling Reaction of 1,1’-Carbonyldiindoles
Takumi Abe and Minoru Ishikura*
*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
Abstract
The palladium-catalyzed intramolecular oxidative coupling reaction of 1,1’-carbonyldiindoles was achieved by using Pd(OAc)2 and Cu(OAc)2, producing 1,1’-carbonyl-2,2’-biindolyls, which were then converted to tjipanazoles D and I.
Published online: 18th June, 2014
■ Generation and Reactions of Heteroaromatic Arynes Using Hypervalent Iodine Compounds
Keisuke Gondo, Juzo Oyamada, and Tsugio Kitamura*
*Department of Chemistry and Applied Chemistry, Faculty of Science and Engineering, Saga University, Honjo-machi, Saga, Japan
Abstract
The heterocyclic aryne precursors, (phenyl)[1-phenyl-6-(trimethylsilyl)benzotriazol-5-yl]iodonium triflate and [3-ethoxycarbonyl-6-(trimethylsilyl)indazol-5-yl](phenyl)iodonium triflate, were prepared from the cycloadducts of 4,5-bis(trimethylsilyl)benzyne generated from (phenyl)[2,4,5-tris(trimethylsilyl)phenyl]iodonium triflate. These precursors provide the corresponding arynes, 1-phenyl-5,6-didehydrobenzotriazole and 3-ethoxycarbonyl-5,6-didehydroindazole, to give the corresponding polycyclic heteroaromatic compounds in good to high yields.
Published online: 23rd July, 2014
■ Design of Aza-Polyquinanes via Fischer Indole Cyclization under Green Conditions
Sambasivarao Kotha* and Ajay Kumar Chinnam
*Department of Chemistry, Indian Institute of Technology Bombay, Powai, Mumbai - 400076, India
Abstract
We have demonstrated a simple and an efficient synthetic route for the synthesis of aza-polyquinane derivatives involving Fischer indole cyclization as a key step under low melting mixture conditions.
Published online: 7th July, 2014
■ Synthesis of Photoreactive Diazirinyl Salicin Derivative to Elucidate Functional Analysis of the Bitter Taste Receptor
Munenori Sakurai, Takuma Yoshida, Lei Wang, Yuta Murai, Katsuyoshi Masuda, Yasuko Sakihama, Yasuyuki Hashidoko, Yasumaru Hatanaka, and Makoto Hashimoto*
*Division of Applied Science, Graduate School of Agriculture, Hokkaido University, Kita 9 Nishi 9, Kita-ku, Sapporo, Hokkaido 060-8589, Japan
Abstract
Salicin (salicyl alcohol glucoside) is a substance well known for its bitter taste. A photoreactive diazirinyl derivative of salicin will be utilized for the functional analysis of interactions between the bitter taste receptor and salicin. Glucosides of salicyl derivatives are more difficult than phenol derivatives that are unsubstituted at the ortho-position. A diazirinyl salicin derivative was synthesized at moderate yields by glucosidation of 2,3,4,6-tetra-O-acetyl-α-D-glucopyranosyl bromide and 2-hydroxy-4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzaldehyde in the presence of a phase-transfer catalyst, nBuEt3NBr, followed by reduction and deprotection.
Published online: 17th July, 2014
■ Synthetic Study of Afritoxinone A: Stereoselective Construction of Furopyranone Moiety
Hideki Abe, Toshihiro Yoshie, Takumi Wagatsuma, Toyoharu Kobayashi, and Hisanaka Ito*
*School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
Stereoselective construction of the furopyranone moiety of the natural product afritoxinone A was demonstrated. This synthetic methodology features (i) stereoselective 1,4-addition of a tricyclic ring system, (ii) oxidative cleavage of the diol, followed by hydration of the resulting dialdehyde group, and (iii) acetalization via cationic cyclization of the pyranediol with the tert-butyl ester tether.
Published online: 8th August, 2014
■ The Cycloaddition of 2-Phenylamino-1-azaazulene with Diphenylacetylene Using Palladium Catalytic Systems
Hiroyuki Fujii,* Shigeki Oka, Ippei Nakamura, Yu Kawai, Reiko Ikeda, Takeo Konakahara, and Noritaka Abe
*Scientific Research Center, Yamaguchi University, 1677-1 Yoshida, Yamaguchi 753-8512, Japan
Abstract
Selective cycloaddition was achieved by the reaction of 2-phenylamino-1-azaazulene (3) with diphenylacetylene (4) in the presence of Pd catalyst providing N-(1-azaazulen-2-yl)-2,3-diphenylindoles.