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
John Daly's Special Issues,Vol. 79, No. 1, 2009
Published online: 1st December, 2008
■ Titanium Tetraiodide Induced Cyclization of 2-(2-Cyanoalk-1-enyl)-β-keto Esters into 2-Iodopyridines
Iwao Hachiya, Yushi Minami, and Makoto Shimizu*
*Department of Chemistry for Materials, Graduate School of Engineering, Mie University, 1577 Tsu, Mie 514-8507, Japan
Abstract
Highly substituted 2-iodopyridines were synthesized from 2-(2-cyanoalk-1-enyl)-β-keto esters under the influence of titanium tetraiodide that worked efficiently for iodination-cyclization.
Published online: 16th January, 2009
■ Synthetic Studies toward (+)-Lysergic Acid: Construction of the Tetracyclic Ergoline Skeleton
Tohru Inoue, Satoshi Yokoshima, and Tohru Fukuyama*
*Graduate School of Pharmaceutical Sciences, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Abstract
We have successfully constructed the tetracyclic skeleton of lysergic acid, which features an acylation at the C3 position of the indole as well as an intramolecular Heck reaction. The optically active D ring unit could be derived from L-pyroglutamic acid via a disrotatory electrocyclic reaction of a dibromocyclopropane.
Published online: 2nd December, 2008
■ Syntheses of N-Acylisoxazolidine Derivatives, Related to a Partial Structure Found in Zetekitoxin AB, a Golden Frog Poison
Toshio Nishikawa,* Daisuke Urabe, and Minoru Isobe
*Graduate of School, Nagoya University, Chikusa, Nagoya, Aichi 464-8601, Japan
Abstract
Syntheses of four N-acylisoxazolidine derivatives related to a partial structure of zetekitoxin AB were described. 13C NMR spectra of these compounds could not explain an unusual chemical shift observed in the N-acylisoxazolidine moiety of zetekitoxin.
Published online: 2nd December, 2008
■ Convergent Synthesis of Fluorescence Labeled Solamin
Naoto Kojima, Takekuni Morioka, Masahiro Yano, Yuki Suga, Naoyoshi Maezaki, and Tetsuaki Tanaka*
*Medicinal and Organic Chemsitry, Graduate School of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Suita, Osaka 560-0871, Japan
Abstract
The convergent synthesis of dansyl-labeled solamin, an antitumor Annonaceous acetogenin, has been achieved. The carbon skeleton was assembled from three fragments: the THF ring fragment, the fluorescent fragment, and the γ-lactone fragment, by asymmetric alkynylation.
Published online: 20th November, 2008
■ An Efficient and Selective Synthetic Method for Fluorine-Containing Benzo[h]quinolines and 1H-Benzo[h]quinolin-2-ones from N-Propargyl-2,4-bis(trifluoroacetyl)-1-naphthylamine
Etsuji Okada,* Dai Shibata, Norikado Tsukushi, Masato Dohura, and Maurice Médebielle
*Department of Chemical Science and Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
N-Propargyl-2,4-bis(trifluoroacetyl)-1-naphthylamine (3) underwent nitrogen-containing heterocyclic ring-formation reactions with active methylene compounds such as dialkyl malonates in the presence of sodium alkoxides. This ring closure reactions were very dependent on reaction temperature to give selectively the corresponding fluorine-containing benzo[h]quinolines (5) at high temperature and 1H-benzo[h]quinolin-2-ones (7 and 8) at low temperature.
Published online: 3rd December, 2008
■ Total Synthesis and the Confirmation of the Revised Structures of Botcinins A and B
Hiroki Fukui, Keisuke Tsuji, Yuma Umezaki, and Isamu Shiina*
*Department of Applied Chemistry, Faculty of Science, Science University of Tokyo, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan
Abstract
The stereoselective total syntheses of botcinins A (1) and B (2), and homobotcinin E (4), a homologue of botcinin E (3), have been achieved starting from a polyoxygenated tetrahydropyran intermediate 15 via formation of botcinic acid (12) and botcineric acid (13). Through the total syntheses, three actual relationships are revealed, that is, (i) the structure of botcinin A (1) is identical with the revised structure of the natural compound, which was formerly assumed to be 3-O-acetyl-2-epibotcinolide (5), (ii) the structure of botcinin B (2) is identical with the revised structure of the natural compound, which was supposed to be 3-O-acetyl-2-epihomobotcinolide (6), and (iii) the structure of the natural compound formerly assumed to be 2-epihomobotcinolide (8) must be revised to that of homobotcinin E (4).
Published online: 26th November, 2008
■ Photo- and Electrochemical Properties of Novel 7-Substituted Naphthyridine Derivatives
Junya Chiba,* Yasuhiro Doi, and Masahiko Inouye*
*Laboratory of Chemical Biology, Faculty of Pharmaceutical Sciences, Toyama University, 2630 Sugitani, Toyama 930-0194, Japan
Abstract
Here we report a new class of 1,8-naphthyridine derivatives, 2-amino-7-(3,4-dimethoxyphenyl)-1,8-naphthyridine, 2-amino-7-(3,4-dihydroxy phenyl)-1,8-naphthyridine, 2-amino-(5,6-dimethoxy-1H-indenyl[2,3-b])-1,8- naphthyridine, and 2-amino-(5,6-dihydroxy-1H-indenyl[2,3-b])-1,8- naphthyridine. All of these compounds were synthesized via naphthyridine-ring forming reaction with 2,6-diaminopyridin-3-carboxaldehyde as a key step. The two dimethoxy derivatives showed predominant fluorescent emission around 400 nm in MeCN. Cyclic voltammetry of the two dihydroxy derivatives in phosphate buffer showed oxidation and reduction potentials around 0.23 and 0.13 V vs. Ag/AgCl, respectively.
Published online: 2nd December, 2008
■ Stereoselective Synthesis of 2,3,5-Trisubstituted Pyrrolidines Using Metathesis-Derived β-Aminoallylsilanes
Alison D. McElhinney and Stephen P. Marsden*
*School of Chemistry, The University of Leeds, Leeds, LS2 9JT, U.K.
Abstract
Amine-functionalised allylsilanes, readily prepared by olefin cross metathesis of protected homoallylamines with allyltrimethylsilane, undergo stereoselective condensation with aldehydes to yield trisubstituted pyrrolidines.
Published online: 18th December, 2008
■ Structure Studies of the Metabolites of Paxillus involutus
Lucyna Mikołajczyk and Wiesław Z. Antkowiak*
*Department of Chemistry, Adam Mickiewicz University, ul. Grunwaldzka 6, 60-780 Poznán, Poland
Abstract
The chemical components of Paxillus involutus were isolated from the freshly collected fruit bodies. Mainly on the basis of the NMR and ESI-MS data, the structures of the unknown pigments were determined as 4-(3,4-dihydroxyphenyl)-2-(4-hydroxyphenyl)-2-(2-pyrrolidon-5-yl)-4-cyclopentene-1,3-dione and (4Z)-5-hydroxy-2-(3,4-dihydroxyphenyl)-5-(4-hydroxyphenyl)-2,4-pentadien-4-olide, respectively.
Published online: 11th December, 2008
■ Synthetic Studies on the Fluorinated Analogs for the Putative Oxindole-Type Metabolites of 5-Halotryptamines
Tomoya Fujiwara, Takayuki Seki, Masaru Miura, and Yoshio Takeuchi*
*Graduate School of Pharmaceutical Sciences, Toyama University, 2630 Sugitani, Toyama, Toyama 930-0194, Japan
Abstract
The suitably protected precursors for direct fluorination, Nb-Boc di-protected 5-fluorotryptamine (13), Nb-acetyl-Nb-Boc protected 5-halotryptamines (15a–c), were treated with SelectfluorTM in MeCN/water in the presence of NaHCO3 to give the corresponding 3-fluorooxindoles 14 and 16a–c in good yields. Removal of the protecting groups of 14 and 16a–c produced (3,5-difluorooxindol-3-yl)ethylamine (8) and N-acetyl-(3-fluoro-5-halooxindol-3-yl)ethylamines (9a–c) in excellent yields, respectively. These compounds are potentially non-epimerizable analogs for the putative metabolites of 5-fluorotryptamine (6) and Nb-acetyl-5-halotryptamines (7a–c).
Published online: 26th December, 2008
■ New Entry to the Asymmetric Synthesis of (–)-Lasubine I and (+)-Subcosine I
Naoki Yamazaki,* Masakazu Atobe, Chihiro Kibayashi, and Sakae Aoyagi*
*Faculty of Pharmaceutical Science, Iwaki Meisei University, , Japan
Abstract
A new synthetic entry to (–)-lasubine I and (+)-subcosine I has been established by employing the (S)-allylalkoxy benzylamine as a chiral synthon. The synthesis involves the formation of an α,β-unsaturated lactone by RCM reaction followed by an intramolecular Michael-type addition reaction as a key step, which enables the stereoselective construction of the cis-quinolizidine skeleton of lasubine I and subcosine I.
Published online: 9th January, 2009
■ Synthesis of Human Cancer Associated Globo-H (MBr1) Glycosylamino Acid: Some Mechanistic and Conformational Reinvestigations
Jianglong Zhu, Qian Wan, Guangbin Yang, Ouathek Ouerfelli, and Samuel J. Danishefsky*
*Department of Chemistry, Columbia University, 3000 Broadway, New York, NY 10027, U.S.A.
Abstract
The synthesis of an extended globo-H (MBr1 antigen) in the form of a glycosylamino acid is reported. By careful NMR analysis, we found an interesting conformational “flip” on the E ring of some synthetic intermediates. An explanation offered for the successful [3+3] coupling of ABC acceptor 11 and DEF donor 10 possessing a C4 free hydroxyl to produce β-galactoside in azaglycosidations is reinforced.
Published online: 3rd July, 2008
■ Out-of-plane Deformation of the Azulene Ring along Its Short Molecular Axis in Crystal and Theoretical Structures of 1,3-Diheterolyl- and 1,3-Diphenylazulenes
Akira Ohta, Shigeyasu Kuroda,* Nguyen Chung Thana, Kouhei Terasawa, Kunihide Fujimori, Keita Nakajima, and Mitsunori Oda*
*bDepartment of Applied Chemistry, Faculty of Engineering, University of Toyama, Gofuku 3190, Toyama, 930-8555 Japan
Abstract
Crystal structures of four simple azulene derivatives, 1,3-diheterolyl- and 1,3-diphenylazulenes, were determined by X-ray diffraction analysis. Three of them showed clear out-of-plane deformation of the azulene ring along its short molecular axis, and one showed a similar but very small deformation. Structural and conformational analyses on substituted azulenes were also performed by DFT molecular orbital calculations. Based on the results of the calculations it was indicated that azulenes could exhibit such deformation depending on their conformations except one case, supporting the results of X-ray analysis. A similar deformation was also found in the crystal structure of a previously reported 1,3-disubstituted azulene whose data were collected from an X-ray crystal structure database.
Published online: 11th August, 2008
■ Subtle Control in Solution and Crystal Structures with Weak Hydrogen Bonds: the Unusual Profile of Dimethyl 3, 12-Dioxo-7, 8 Dithia 4, 11-Diazabicyclo[12.2.2]octadeca-1(16), 14, 17-triene 5, 10-Dicarboxylate (TDA1)
Isabella L. Karle,* Lulu Huang, Punna Venkateshwarlu, A. V. S. Sarma, and Subramania Ranganathan
*Laboratory for the Structure of Matter, Naval Research Laboratory, Washington D.C. 20375-5341
Abstract
The structural features of the title compound were determined or examined by three diverse procedures: single crystal X-ray diffraction analysis, solution spectroscopic procedures and quantum mechanical theoretical calculations. The conformational asymmetry of the macrocycle provides the opportunity to form one strong N-H···O-C intermolecular hydrogen bond, as well as, a number of weak C-H···O-C bonds. The interior of the macrocycle has short approaches for N-H···π and N-H···S. The many weak hydrogen bonds cooperate to form a very hard, robust crystal. Crystal parameters: C18H22N2O6S2, P212121, a = 5.108(1) Å, b = 18.948(4) Å, c = 21.029(3) Å, α = β = γ = 90°. Quantum chemical calculations have provided a strong foundation for weak hydrogen bonds. Contrary to popular belief, the present work has conclusively proved that the importance of weak hydrogen bonds is perhaps underestimated.
Published online: 16th September, 2008
■ Synthesis and Biological Evaluation of Inhibitors of Botulinum Neurotoxin Metalloprotease
Chenbo Wang, Julia Widom, Filip Petronijevic, James C. Burnett, Jonathan E. Nuss, Sina Bavari, Rick Gussio, and Peter Wipf*
*Department of Chemistry, University of Pittsburgh, Pittsburgh, Pennsylvania, 15260, U.S.A.
Abstract
Based on the lead therapeutic agent NSC 240898, a new series of heterocyclic inhibitors of the BoNT serotype A metalloprotease has been generated. Highlights of the synthetic sequences include Sonogashira couplings of polysubstituted building blocks and gold-catalyzed indole formations. Preliminary structure-activity relationship studies afford detailed insights into the steric and electrostatic properties of the pharmacophore of this molecular scaffold.
Published online: 22nd September, 2008
■ De Novo Asymmetric Approach To 8a-epi-swainsonine
Jason A. Coral, Haibing Guo, Mingde Shan, and George A. O’Doherty*
*Department of Chemistry, West Virginia University, Morgantown, WV 26506, USA
Abstract
An improved method for the synthesis of (-)-8a-epi-swainsonine has been developed with 9 fewer steps than the original route. The synthetic improvements include a two-step procedure for the preparation of benzyl 4-(furan-2-yl)-4-oxobutylcarbamate from pyrrolidin-2-one and a two-step procedure for the preparation of benzyl 3-((3aS,4S,6R,7aR)-4-(benzyloxy)tetrahydro-2,2-dimethyl-7-oxo-3aH-[1,3]dioxolo[4,5-c]pyran-6-yl)- propylcarbamate from benzyl 3-((2R,6S)-6-(benzyloxy)-3,6-dihydro-3-oxo-2H-pyran-2- yl)propylcarbamate.
Published online: 22nd September, 2008
■ Synthesis, Structure and Catalytic Activity of Macrocyclic NHC Pd Pincer Complexes
Noriaki Watarai, Hiroyasu Kawasaki, Isao Azumaya, Ryu Yamasaki, and Shinichi Saito*
*Department of Chemistry, Faculty of Science, Tokyo University of Science, Kagurazaka, Shinjuku, Tokyo 162-8601, Japan
Abstract
We synthesized a series of new N-heterocyclic carbene (NHC) macrocyclic Pd pincer complexes (17-22) by the reaction of Pd(OAc)2 or Pd2(dba)3 with the corresponding macrocycles, which were prepared by the coupling reaction of dibromides with bisimidazoles. The complex adopted twisted conformation, and the activation energy of the conformational interconversion of the macrocycle was determined by VT-NMR. We also examined the catalytic activity of these Pd complexes in Mizoroki-Heck and oxidative alkynyl-alkynyl homocoupling reactions.
Published online: 16th October, 2008
■ An Efficient Synthesis of Procyanidins Using Equimolar Condensation of Catechin and/or Epicatechin Catalyzed by Ytterbium Triflate
Yoshihiro Mohri, Masayoshi Sagehashi, Taiji Yamada, Yasunao Hattori, Keiji Morimura, Yasunori Hamauzu, Tsunashi Kamo, Mitsuru Hirota, and Hidefumi Makabe*
*Shinshu University, 8304 Minamiminowa-mura, Kamiina-gun, Nagano 399-4598, Japan
Abstract
Stereoselective synthesis of catechin and epicatechin dimers under intermolecular condensation of equimolar amount of catechin derivatives catalyzed by Yb(OTf)3. The coupled products were successfully converted to procyanidins B1, B2, B3, and B4, respectively. Procyanidins B1, B2, B3, and B4 could be used as standard compounds for identifying the polyphenols in natural source.
Published online: 16th October, 2008
■ Synthesis, Determination of the Absolute Stereochemistry, and Evaluations at the Nicotinic Acetylcholine Receptors of a Hydroxyindolizidine Alkaloid from the Ant Myrmicaria melanogaster
Dejun Zhou, Naoki Toyooka,* Hideo Nemoto, Kaoru Yamaguchi, Hiroshi Tsuneki, Tsutomu Wada, Toshiyasu Sasaoka, Hideki Sakai, Yasuhiro Tezuka, Shigetoshi Kadota, Tappey H. Jones, H. Martin Garraffo, Thomas F. Spande, and John W. Daly
*Faculty of Pharmaceutical Sciences, Toyama University, 2630 Sugitani, Toyama, Toyama 930-0194, Japan
Abstract
The first chiral synthesis of new hydroxyindolizidine alkaloid (1) detected in the ant Myrmicaria melanogaster has been achieved, and its absolute stereochemistry was determined to be 3S, 5R, 8S, 9S by the present chiral synthesis.
Published online: 30th October, 2008
■ Asymmetric Synthesis of 4-Substituted 2,6-Dioxopiperidine-3-carbonitrile by Using Thiourea-Catalyzed Asymmetric Michael Addition
Tsubasa Inokuma, Yuuki Nagamoto, Shota Sakamoto, Hideto Miyabe, Kiyosei Takasu, and Yoshiji Takemoto*
*Graduate School of Pharmaceutical Sciences, Kyoto University, 46-29 Yoshida-shimoadachi-machi, Sakyo-ku, Kyoto 606-8501, Japan
Abstract
An enantioselective Michael addition of several α,β-unsaturated carbonyl compounds with malononitrile catalyzed by a bifunctional thiourea is described. We also demonstrate the transformation of Michael adduct into an enantiomerically enriched functionalized piperidine.
Published online: 28th January, 2009
■ Dioicine: A Novel Prenylated Purine Alkaloid from Gymnocladus dioicus
Richard W. Fitch,* Thomas F. Spande, H. Martin Garraffo, Rachael R. Chase, Mylaka A. Clinedinst, Derek A. Parkes, Richard Reed, Noel F. Whittaker, and John W. Daly
*Department of Chemistry, Indiana State University, 200 North Seventh Street, Terre Haute, Indiana, U.S.A.
Abstract
The Kentucky coffeetree, Gymnocladus dioicus (L., K. Koch) is a leguminous tree reputed to be toxic to livestock and to contain the toxic nicotinic acetylcholine receptor agonist cytisine. Analysis of extracts of various tree parts by gas chromatography-mass spectrometry failed to reveal the presence of cytisine. Neither [3H]-epibatidine binding in rat cerebral cortex nor functional fluorescence assays in cultured cells expressing nicotinic receptor subunits indicated significant activity. However, a novel purine alkaloid, 3-((E)-3-methylbuta-1,3-dienyl)-1,7-dimethylisoguanine, which we have named dioicine, was identified as the major lipophilic alkaloid in the methanolic extract from leaves and seeds. Dioicine and its hydrolysis products are likely to be responsible for the historical use of the tree’s seeds as a coffee substitute. Herein we describe the isolation, structure elucidation and preliminary biological characterization of dioicine.
Published online: 23rd October, 2008
■ Reaction of β-Trifluoroacetylketene Acetals and β-Trifluoroacetylvinyl Ethers with 1,2-Phenylenediamines Accessing Fluorine-Containing Benzo[b][1,4]diazepine Derivatives: A Molecular Orbital Calculation Study
Norio Ota, Yasuhiro Kamitori,* Naoya Terai, Tsuneaki Sakata, and Etsuji Okada*
*Department of Chemical Science and Engineering, Graduate School of Engineering, Kobe University, 1-1 Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
β-Trifluoroacetylketene acetals (1) were found to react easily with 1,2-phenylenediamines to give dihydrobenzodiazepinols (5a) together with benzodiazepines (6a) under very mild conditions. In contrast, β-trifluoroacetyl-α-phenylvinyl ethers (2) and β-trifluoroacetylvinyl ethers (3) exclusively yielded O-N exchanged products (9) when they were reacted with 1,2-phenylenediamines. The factors determining product formation by the reaction of each of three similar substrates (1-3) with 1,2-phenylenediamine were elucidated on the basis of molecular orbital calculations. The dehydration processes converting dihydrobenzodiazepinols (5 and 7) to the corresponding benzodiazepines (6 and 8) are also discussed.
Published online: 1st December, 2008
■ Synthesis of Aza-Bridged Calix(4-methoxy)triazines toward Flattened π-Conjugated Macrocycles
Hiroyuki Tanaka, Ayako Wada, Motoo Shiro, Kazuhito Hioki, Daiki Morisaki, and Munetaka Kunishima*
*Faculty of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
Abstract
Calixtriazines containing a 4-alkoxy-1,3,5-triazine backbone were efficiently synthesized by sequential fragment coupling started from 4-alkoxy-2,6-dichrolo-1,3,5-triazine. These macrocycles tend to form flattened conformations, leading to a stable π-conjugated system, presumably due to the electronic features of the alkoxy-substituent on the triazine rings.
Published online: 6th November, 2008
■ A New Trimeric Hydrolyzable Tannin, Oenotherin T2, Isolated from Aerial Parts of Oenothera tetraptera Cav.
Shoko Taniguchi, Yoko Imayoshi, Takashi Yoshida, and Tsutomu Hatano*
*Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, 1-1-1 Tsushima-naka, Okayama 700-8530, Japan
Abstract
A new hydrolyzable tannin, oenotherin T2, was isolated from the aerial parts of Oenothera tetraptera Cav., together with 15 known polyphenolic compounds. The trimeric structure of oenotherin T2 was elucidated based on spectroscopic data and chemical correlation with oenotherin T1.
Published online: 13th November, 2008
■ Synthesis of 1,2,4-Triazin-5-ones through [4+2] Cycloaddition of 1,2,4-Triaza-1,3-dienes with Diphenylketene
Tatsuya Nakai, Kyoko Fukutomi, Hiroaki Yanagisawa, Tomomi Kawasaki, and Masanori Sakamoto*
*Kyushu University of Health and Welfare, , Japan
Abstract
On heating 1,2,4-triaza-1,3-dienes 1 with diphenylketene, [4+2] cycloaddition took place smoothly to afford the corresponding 1,2,4-triazin-5-one derivatives 2 in good yield.
Published online: 10th November, 2008
■ Synthesis of Nb-Acyltryptamines and Their 1-Hydroxy-tryptamine Derivatives as New α2-Blockers
Koji Yamada, Yoshio Tanaka, and Masanori Somei*
*Faculty of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan
Abstract
Nb-Acyl- and Nb-acyl-1-hydroxytryptamines are found to be novel and structurally simple α2-blocker for the treatment of erectile dysfunction.
Published online: 28th November, 2008
■ Ruthenium Tetroxide Oxidation of N,N’-DiBoc-Hexahydropyridazines
Mamoru Kaname, Shigeyuki Yoshifuji, and Haruki Sashida*
*Faculty of Pharmaceutical Sciences, Hokuriku University, 3-Ho, Kanagawa machi, Kanazawa 920-1181, Japan
Abstract
The ruthenium tetroxide (RuO4) oxidation of the 3-substituted N,N’-diBochexahydropyridazines gave the 6-oxohexahydropyridazines in good to high yields, whereas the oxidation of the unsubstituted ones also gave the 3,6-dioxo derivatives. The 3,6-cis-disubstituted pyridazines were essentially oxidized to give the 3-hydroxypyridazines; no oxidation of the trans-derivative occurred.
Published online: 13th November, 2008
■ Synthesis and Thermal Stability of 3-Substituted 3-Benzostibepines
Shuji Yasuike, Masaaki Ikoma, Naoki Kakusawa, Takashi Tsuchiya, and Jyoji Kurita*
*Faculty of Pharmaceutical Sciences, Hokuriku University, 3-Ho, Kanagawa machi, Kanazawa 920-1181, Japan
Abstract
Fully unsaturated 3-benzostibepines having various aryl groups on antimony have been prepared by a ring closure reaction of an appropriate antimony dihalide (ArSbBr2) with (Z,Z)-1,2-bis(2-lithiovinyl)benzene generated by treatment of (Z,Z)-1,2-bis(2-bromovinyl)benzene with t-BuLi. All the stibepines obtained here are thermolabile in solution toward heteroatom extrusion. The half-lives of the stibepines estimated from 1H-NMR spectral analysis revealed that the thermal stabilities of the stibepines bearing a heteroatom moiety (N, O) in the vicinity of the antimony are far less stable than others.
Published online: 21st November, 2008
■ Iodobenzene Diacetate–Promoted N–N and N–O Bond Formation for Pyrazolo- and Isoxazolopyrimidine Syntheses
Yasunari Monguchi, Kazuyuki Hattori, Tomohiro Maegawa, Kosaku Hirota, and Hironao Sajiki*
*Laboratory of Medicinal Chemistry, Gifu Pharmaceutical University, 6-1 Mitahora-higashi 5-chome, Gifu 502-8585, Japan
Abstract
Pyrazolo[3,4-d]pyrimidine-4,6-dione derivatives were efficiently synthesized via the intramolecular N–N bond coupling of 5-iminomethyl-6-aminouracil derivatives using iodobenzene diacetate. The oxidative coupling was also applied to the analogous N–O bond formation producing isoxazolo[3,4-d]primidine-4,6-dione derivatives.
Published online: 21st November, 2008
■ Facile Syntheses of Three Ahp-Type Building Blocks with Complementary Reactivity
Wen Chen, Xiao Zheng, Yuan-Ping Ruan, and Pei-Qiang Huang*
*Department of Chemistry and Key Laboratory for Chemical Biology of Fujian Province, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005, China
Abstract
Two protected 3-amino-6-hydroxy-2-piperidone derivatives (Ahp, 12 and 6), as well as a thioether analogue (7) were synthesized starting from L-glutamic acid in four, five, and six steps respectively. The Ahp derivatives 12 and 6 are not only the structural feature found in many naturally occurring bioactive depsipeptides, but also precursors of the N-acyliminium such as D; while the (S)-thioether 7 was shown to be an effective synthetic equivalent of the novel 2-piperidone N-α-carbanion E via the lithium-naphthalenide (LN)-mediated reductive lithiation, capable of reacting with carbonyl compounds without an acidic α–position to give the α-hydroxyalkylation products.