Special Issue

Ekkehard Winterfeldt's Special Issues, Vol. 74, No. 1, 2007

97 data found. 61 - 90 listedFirst Previous Next Last
Paper | Special issue | Vol 74, No. 1, 2007, pp. 637 - 648
Published online: 4th October, 2007
DOI: 10.3987/COM-07-S(W)44
An Alternative Chiral Synthesis of Wieland-Miescher Ketone Mediated by (S)-2-(Pyrrolidinylmethyl)pyrrolidine: Remarkable Effects of Brønsted Acid

Yuichi Akahane, Naoko Inage, Takashi Nagamine, Kohei Inomata,* and Yasuyuki Endo

*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

The enantioselectivity of the intramolecular asymmetric aldol reaction mediated by (S)-2-(pyrrolidinylmethyl)pyrrolidine to prepare Wieland- Miescher ketone was examined in detail. A remarkable inversion of enantioselectivity was observed when a Brønsted acid was used as a co-catalyst. Development of the reaction to Robinson annulation was successfully achieved by the use of (S)-2-(pyrrolidinylmethyl)pyrrolidine as a Brønsted base, followed by trifluoroacetic acid as a Brønsted acid.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 649 - 660
Published online: 16th October, 2007
DOI: 10.3987/COM-07-S(W)49
A Facile Synthesis of 1,2-Dihydroisoquinolines by Three-Component Reaction

Kentaro Iso, Salprima Yudha S., Menggenbateer, and Naoki Asao*

*Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, Sendai 980-8578, Japan

Abstract

1,2-Dihydroisoquinoline frameworks are constructed efficiently by three-component reactions with ortho-alkynylbenzaldehydes, primary amines, and pronucleophiles under mild conditions.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 661 - 671
Published online: 26th October, 2007
DOI: 10.3987/COM-07-S(W)50
Zinc Iodide as an Efficient Catalyst in the TMS-Azide Modified Passerini Reaction

Eva S. Schremmer and Klaus T. Wanner*

*Center for Drug Research, Department of Pharmacy, Ludwig-Maximilians-University Munich, Butenandtstr. 7, Haus C, D-81377 Munich, Germany

Abstract

Employing ZnI2 as catalyst significantly improves the yields of the TMS-azide modified Passerini reaction as a short and simple method for the synthesis of 1,5-disubstituted tetrazoles.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 673 - 682
Published online: 12th October, 2007
DOI: 10.3987/COM-07-S(W)51
An Efficient Synthesis of Nitrogen Heterocycles by Cp*Ir-Catalyzed N-Cycloalkylation of Primary Amines with Diols

Ken-ichi Fujita, Takeshi Fujii, Atsuo Komatsubara, Youichiro Enoki, and Ryohei Yamaguchi*

*Graduate School of Human and Environmental Studies, Kyoto University, Kyoto 606-8501, Japan

Abstract

A new efficient method for the N-cycloalkylation of primary amines with diols catalyzed by a Cp*Ir complex have been developed. A variety of five-, six-, and seven-membered cyclic amines are synthesized in good to excellent yields in environmentally benign and atom economical manner with the formation of only water as a coproduct. A large scale synthesis of N-benzylpiperidine and a two-step asymmetric synthesis of (S)-2-phenylpiperidine using (R)-1-phenylethylamine as a starting primary amine have been also achieved.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 683 - 700
Published online: 12th October, 2007
DOI: 10.3987/COM-07-S(W)54
Synthesis of Benzylisoquinoline Derivatives Possessing Electron-Withdrawing Substituents on the Benzene Ring of the Isoquinoline Skeleton

René Severin, Didin Mujahidin, Jessica Reimer, and Sven Doye*

*Institute of Pure and Applied Chemistry, University of Oldenbrug, Carl-von-Ossietzky-Str. 9-11, D-26111 Oldenbrug, Germany

Abstract

3,4-Dihydrobenzylisoquinolines and 1,2,3,4-tetrahydrobenzyl- isoquinolines possessing electron withdrawing substituents on the benzene ring of the isoquinoline framework are easily accessible by a synthetic approach that takes advantage of a Sonogashira coupling to build up the C1-C8a bond of the isoquinoline skeleton and a Ti-catalyzed intramolecular hydroamination of an alkyne to close the heterocyclic ring.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 701 - 720
Published online: 30th October, 2007
DOI: 10.3987/COM-07-S(W)56
Synthesis of Both Enantiomers of Protoberberines via Laterally Lithiated (S)-4-Isopropyl-2-(o-tolyl)oxazolines

Tsutomu Fukuda and Masatomo Iwao*

*Department of Applied Chemistry, Faculty of Engineering, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan

Abstract

The addition of the laterally lithiated (S)-4-isopropyl-2-(o- tolyl)oxazoline (1) to 6,7-dimethoxy-3,4-dihydroisoquinoline (2) proceeded in modest diastereoselectivity. However, the addition products (3a) and (3b) were easily separated by column chromatography over silica gel. Acid-catalyzed lactamization of 3a and 3b followed by LiAlH4-reduction afforded the corresponding optically pure protoberberines (8a) and (8b), respectively. This procedure was successfully applied to the synthesis of both enantiomers of xylopinine and bharatamine.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 721 - 730
Published online: 12th October, 2007
DOI: 10.3987/COM-07-S(W)57
A Facile and Convenient Synthetic Method for 2-Bis(trifluoroacetyl)methylene- and 2-Trifluoroacetylmethylene-2,3-dihydro-3-methylthiazoles

Norio Ota, Etsuji Okada,* Yasuhiro Kamitori, Dai Shibata, and Maurice Médebielle

*Department of Chemical Science and Engineering, Faculty of Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan

Abstract

2,3-Dimethylthiazolium iodides (1) reacted easily with trifluoroacetic anhydride in the presence of pyridine to give 2-bis(trifluoroacetyl)methylene-2,3-dihydro-3-methylthiazoles (2) in excellent yields. Deacylation of 2 proceeded readily in moderate to high yields by acid catalyst such as silica gel and aqueous hydrochloric acid to afford the corresponding 2-trifluoroacetylmethylene-2,3-dihydro-3-methylthiazoles (3), which were smoothly reconverted into diacylated compounds (2) with trifluoroacetic anhydride. The highly poralized structure of 2 was also briefly discussed.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 731 - 742
Published online: 26th October, 2007
DOI: 10.3987/COM-07-S(W)58
Synthesis of 4-Benzyliden-2-oxazolidinone Derivatives via Gold-Catalyzed Intramolecular Hydroamination

Stefanie Ritter, Kristina Hackelöer, and Hans-Günther Schmalz*

*Institute of Organic Chemistry, University of Kologne, Greinstr. 4, 50939 Köln, Germany

Abstract

AuCl-catalyzed intramolecular hydroamination of N-aryl-O-propargyl carbamates (3) efficiently affords (Z)-N-aryl-4-benzyliden-2-oxazolidinones (4) via a 5-exo dig cyclization. The reaction proceeds in acetonitrile at 60 °C and requires tBuOK or KOH as a base co-catalyst. It tolerates the presence of multiple substituted aryl units with electron donating methoxy groups. The method opens a convenient, flexible and operationally simple access to a new class of twisted molecules with potentially interesting biological properties.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 743 - 761
Published online: 16th November, 2007
DOI: 10.3987/COM-07-S(W)59
Synthesis of Nitrosoalkyl- and Amino-Substituted α,β-Unsaturated Ketones by Cleavage of the N-O-Bond of Bicyclic Δ4-Isoxazolines

Markku Lager, Paul Dietrich, Dirk Weinrich, and Karola Rück-Braun*

*Department of Chemistry, Technical University of Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany

Abstract

The N-O-bond cleavage of bicyclic Δ4-isoxazolines prepared from five-membered cyclic nitrones was studied. Proline-derived bicyclic isoxazolines furnished exclusively acylic nitrosoalkyl-substituted α,β-unsaturated ketones upon treatment with m-CPBA. The nitroso compound 16 was characterized as stable diazo-dioxyde by X-ray analysis. For the N-O-bond cleavage of C3-H-substituted bicyclic Δ4-isoxazolines a Pd(PPh3)4-promoted cleavage protocol in the presence of silanes furnishing enaminones is described.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 763 - 769
Published online: 2nd November, 2007
DOI: 10.3987/COM-07-S(W)60
Twist Angles and Torsional Potentials of 2,2’-Bibenzothiophene, 2,2’-Biindole, and 2,2’-Bibenzofuran

Naoto Hayashi* and Hiroyuki Higuchi*

*Department of Chemistry, Faculty of Science, Toyama University, Gofuku 3190, Toyama 930, Japan

Abstract

Twist angles and torsional potentials of 2,2’-bibenzothiophene (bi-BT), 2,2’-biindole (bi-BP), and 2,2’-bibenzofuran (bi-BF) were obtained using HF/6-31G(d) methods. Due to the effect of fused benzene rings, both compounds were revealed to have higher rotational barriers and more planar structures at energy minima than 2,2-bithiophene (bi-T), 2,2’-bipyrrole (bi-P), and 2,2’-bifuran (bi-F), respectively. Calculations on 2,2’-binaphtho[2,3-b]thiophene (bi-BBT), 2,2’-bibenzo[h]indole (bi-BBP), and 2,2’-binaphtho[2,3-b]furan (bi-BBF) were also conducted to study the effect of an additional fusion of another benzene ring.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 771 - 790
Published online: 30th October, 2007
DOI: 10.3987/COM-07-S(W)63
A New Preparative Method of Aryl Sulfonate Esters by Using Cyclic Organobismuth Reagents

Naoto Sakurai and Teruaki Mukaiyama*

*Center for Basic Research, The Kitasato Institute, 6-15-5 (TCI), Toshima, Kita-ku, Tokyo 114-0003, Japan

Abstract

A new method for the preparation of aryl sulfonate esters by using a cyclic pentavalent bismuth is described. Aryl sulfonate esters are formed in good to high yields by treating 10-arylphenothiabismine 5,5-dioxides, m-chloroperoxybenzoic acid (m-CPBA) and various sulfonic acids in dichloromethane.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 791 - 802
Published online: 9th November, 2007
DOI: 10.3987/COM-07-S(W)65
Reaction of 2-Alkylthiopyridinium Salts with Active Methylene Compounds

Masato Hoshino, Tsuyoshi Taguchi, Hiroto Nakano, Hiroshi Tomisawa, Hisao Matsuzaki, and Reiko Fujita*

*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

Reactions between active methylene compounds and 2-alkyllthio-1-alkylpyridinium iodides in the presence of sodium hydride, were found to occur at the 2 or 4-position. In contrast, 2-chloro-1-methylpyridinium iodide reacted at the 2-position, whereas 6-chloro-2-methylthiopyridinium iodide reacted at the 6-position to yield only one product. Chemoselectivity of the pyridinium salt was calculated using molecular orbital (MO) calculations.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 803 - 817
Published online: 9th November, 2007
DOI: 10.3987/COM-07-S(W)69
Synthesis of cis-Fused Pyranopyran and Pyranopyridine Templates by Ring Rearrangement Metathesis

Alexander Niethe and Siegfried Blechert*

*Institute of Chemistry, Technical University of Berlin, Strasse des 17. Juni 135, D-10623 Berlin, Germany

Abstract

A short, racemic and multigram scale synthesis of two novel templates is described. The key steps of the synthesis are ring rearrangement metathesis of strained tropane-derivatives into cis-fused pyranopyrans and pyranopyridines and subsequent functionalisation via cross metathesis and stereoselective dihydroxylation.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 819 - 825
Published online: 13th November, 2007
DOI: 10.3987/COM-07-S(W)73
Theoretical Studies of 5-exo Selective Intramolecular Cyclization of O-Alkynylbenzoic Acid Catalyzed by Organic Base

Masahiro Terada,* Chikashi Kanazawa, and Masahiro Yamanaka*

*Graduate School of Science, Graduate School of Science, Tohoku University, Aramaki, Aoba-ku, sendai 980-8578, Japan

Abstract

Theoretical studies of the organic base-catalyzed 5-exo intramolecular cyclization of o-alkynylbenzoic acid were documented. The acidic fragment participating in the transition states was shown to reduce the activation energy significantly on the basis of hybrid DFT (BHandHLYP) calculation of 5-exo and 6-endo transition states. Furthermore, preference for the 5-exo cyclization mode was rationalized by natural population analysis of optimized structures of the transition states and the reactants.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 827 - 834
Published online: 26th November, 2007
DOI: 10.3987/COM-07-S(W)74
Pd(II)-Catalyzed Enantioselective Intramolecular Heck-Type Reaction to Construct Chiral Sulfonamide Rings

Katsuhiro Akiyama and Koichi Mikami*

*Department of Applied Chemistry, Graduate School of Science and Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8552, Japan

Abstract

The first example of enantioselective intramolecular Heck-type reaction to construct chiral quaternary carbon centers of sulfonamide rings is reported. The reaction provides the expected Heck products along with the unexpected olefin reduction products. We discovered the catalyst prepared from (S,S)-chiraphos and Pd2dba3 to afford the products in high yields and enantioselectivities up to 86% ee at room temperature. Deuterated solvent and base are also examined to elucidate the mechanism of reduction of olefin. Pd hydride species produced from β-elimination are responsible for olefin reduction.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 835 - 842
Published online: 30th October, 2007
DOI: 10.3987/COM-07-S(W)75
Synthesis of Phthalocyanine Fused with Bicyclo[2.2.2]octadienes and Thermal Conversion into Naphthalocyanine

Taiji Akiyama, Atsuko Hirao, Tetsuo Okujima, Hiroko Yamada, Hidemitsu Uno, and Noboru Ono*

*Department of Chemistry, Faculty of Science, Ehime University, Matsuyama 790-8577, Japan

Abstract

Mg complex of phthalocyanine fused with bicyclo[2.2.2]octadiene (BCOD) units is prepared by the reaction of BCOD-fused phthalonitrile with Mg(OPr)2 in PrOH at 100 °C overnight in 42% yield. Subsequent heating the product at 250 °C results in clean formation naphthalocyanine via the retro Diels-Alder reaction. An attempt to the synthesis of BCOD-fused tetraazaporphyrin by the similar cyclization of the Diels-Alder adduct of dicyanoacetylene with 1,3-cyclohexadiene was unsuccessful.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 843 - 848
Published online: 9th November, 2007
DOI: 10.3987/COM-07-S(W)76
Lycopladine E, a New C16N1-Type Alkaloid from Lycopodium complanatum

Takaaki Kubota, Hiroko Yahata, Kan’ichiro Ishiuchi, Yutaro Obara, Norimichi Nakahata, and Jun’ichi Kobayashi*

*Graduate School of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan

Abstract

A new C16N1-type alkaloid, lycopladine E (1), has been isolated from the club moss Lycopodium complanatum, and the structure and absolute stereochemistry were elucidated on the basis of spectroscopic data and chemical correlation.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 849 - 853
Published online: 16th November, 2007
DOI: 10.3987/COM-07-S(W)77
Seragadine A, a β-Carboline Alkaloid from Marine Sponge

Kohei Nozawa, Masashi Tsuda, Takaaki Kubota, 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

A new quaternary β-carboline alkaloid, seragadine A (1), and three known related alkaloids (2 ~ 4) have been isolated from an Okinawan Haplosclerida sponge (SS-1022). The structure of 1 was determined by the spectroscopic data and its synthesis.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 855 - 862
Published online: 4th December, 2007
DOI: 10.3987/COM-07-S(W)79
Synthesis of the Cyclobutane Moiety of Providencin

Tanja Gaich, Vladimir Arion, and Johann Mulzer*

*Institute of Organic Chemistry, University of Vienna, Währingerstraße 38, A-1090 Vienna, Austria

Abstract

A short and stereoselective synthesis of the protected cyclobutane diol moiety of the natural compound providencin is reported. Key step is the chemo- and stereoselective hydroboration of the silyl-enol ether obtained from commercially available bicyclo[3.2.0]hept-6-en-2-one.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 863 - 872
Published online: 30th November, 2007
DOI: 10.3987/COM-07-S(W)82
Synthesis of 1,1-Dichloro-2,5-diphenylsilacyclopent-3-enes by the Chlorination of 1,1-Diethoxy- and Bis(optically Active Alkoxy)-2,5-diphenylsilacyclopent-3-enes

Kenichi Miyakawa, Chihiro Fujii, Koji Arimitsu, and Yukinori Nagao*

*Department of Industrial Chemistry, Faculty of Science and Technology, Science University of Tokyo, 2641 Yamazaki, Noda, Chiba 278-8510, Japan

Abstract

The 1,1-diethoxy-2,5-diphenylsilacyclopent-3-ene was reacted with optically active alcohols ((-)-menthol, (-)-borneol, (-)-amyl alcohol ) to obtain the corresponding 1,1-bis(optically active alkoxy)-2,5-diphenyl-silacyclopent-3-enes including various ratios of diastereomers. The 1,1-diethoxy and dialkoxy-2,5-diphenylsilacyclopent-3-enes were reacted with acetylchloride in the presence of zinc chloride to produce 1,1-dichloro-2,5-diphenyl-silacyclopent-3-ene having reactive substituents including various ratios of diastreomers.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 873 - 894
Published online: 7th December, 2007
DOI: 10.3987/COM-07-S(W)83
Ring Closing Metathesis Reactions of Imidazole Derivatives

Carl J. Lovely,* Yingzhong Chen, and E. Vindana Ekanayake

*Department of Chemistry, The University of Texas at Arlington, 502 Yates Street, Arlington, TX 76019, U.S.A.

Abstract

A series of diene substituted imidazole derivatives has been prepared from the corresponding haloimidazoles via halogen-magnesium exchange and electrophile quench. These derivatives were explored as susbstrates in a ring closing metathesis reaction, which was successful if the imidazolium ion was used. In addition, one successful example of a ring closing metathesis reaction of an enyne derivative was performed, with the resulting diene successfully engaging in a Diels-Alder reaction.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 895 - 912
Published online: 4th December, 2007
DOI: 10.3987/COM-07-S(W)84
Transition Metals in Organic Synthesis, Part 84. Application of Iron- and Nickel-Mediated Coupling Reactions to the Total Synthesis of the Neuronal Cell Protecting Substance (±)-Carquinostatin A

Wolfgang Fröhner, Kethiri R Reddy, and Hans-Joachim Knölker*

*Institute of Organic Chemistry, Technical University Dresden, Bergstrasse 66, D-01069 Dresden, Germany

Abstract

Using iron- and nickel-mediated coupling reactions as key steps a convergent and highly efficient total synthesis of the potent neuronal cell protecting alkaloid (±)-carquinostatin A has been accomplished.

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Paper | Special issue | Vol 74, No. 1, 2007, pp. 913 - 925
Published online: 7th December, 2007
DOI: 10.3987/COM-07-S(W)86
Synthesis and Characterization of 1-(2H-Tetrazol-5-yl)-1,4,7,10-tetraazacyclododecane and Its Zn(II), Ni(II) and Cu(II) Complexes

Kristina Woinaroschy, Andrei Ursu, and Burkhard König*

*Department of Chemistry, University of Regensburg, Universitätsstraße 31, D-93040 Regensburg, Germany

Abstract

As part of an ongoing effort to develop new metal complexes of tetraazamacrocycles with novel properties in coordination or functionalization we report here the synthesis of a new derivative of 1,4,7,10-tetraazacyclododecane (cyclen) with a tetraazole moiety directly bound to the azamacrocycle. The new ligand was obtained by reaction with cyanogen bromide giving the cyanamide, followed by a [2+3] cycloaddition with NaN3 to yield the tetraazole. The ligand and its Zn(II), Ni(II) and Cu(II) complexes were fully characterized by analytical methods. X-ray structure analysis of the Ni(II) compound shows the formation of a stable dimer by coordination of each of the two tetraazole substituents to the neighboring metal cation. Potentiometric titrations of the metal complexes indicate a possible conversion of the monomer to the dimeric structure in solution and show the pKa of the NH-atom on the tetraazole substituent to be between 4.03 and 5.3 depending on the metal ion coordinated by cyclen.

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Note | Special issue | Vol 74, No. 1, 2007, pp. 927 - 930
Published online: 31st May, 2007
DOI: 10.3987/COM-07-S(W)1
Synthesis of Artekeiskeanin A: A New Coumarin Monoterpene Ether from Artemisia keiskeana

Dominick Maes, Kris Van Syngel, and Norbert De Kimpe*

*Department of Organic Chemistry, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium

Abstract

The first total syntheses of artekeiskeanin A, a natural coumarin monoterpene ether from Artemisia keiskeana, and 7-geranyloxy-6-methoxycoumarin, a coumarin monoterpene ether with antifungal and antitumor properties, are reported. Key step in the synthesis of artekeiskeanin A is the stereoselective oxidation of the geranyloxy side chain of 7-geranyloxy-6-methoxycoumarin under microwave irradiation.

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Note | Special issue | Vol 74, No. 1, 2007, pp. 931 - 936
Published online: 27th April, 2007
DOI: 10.3987/COM-07-S(W)2
Cell Growth and Cell Cycle Inhibitory Activities of 20-Epidiosgenyl Saponin from Calamus insignis

Takashi Ohtsuki, Noriko Kaneko, Takashi Koyano, Thaworn Kowithayakorn, Nobuo Kawahara, Yukihiro Goda, and Masami Ishibashi*

*Graduate School of Pharmaceutical Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan

Abstract

A new 20 epi-diosgenyl saponin (1) was isolated from the stems of Calamus insignis (Palmae) by bioassay guided purification. The chemical structure of 1 was established on the basis of spectroscopic analysis and chemical means. Compound 1 showed cell growth inhibitory activity against HeLa cells (IC50; 5.1 μM) and exhibited a cell cycle inhibitory effect at the G2/M stage at the concentration of 2.9 μM by flow cytometric analysis.

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Note | Special issue | Vol 74, No. 1, 2007, pp. 937 - 941
Published online: 20th July, 2007
DOI: 10.3987/COM-07-S(W)9
Ilicifoliosides A and B, Bis-Secoiridoid Glycosides from Osmanthus ilicifolius

Shigeaki Sakamoto, Koichi Machida, and Masao Kikuchi*

*Department of 2nd Analytical Chemistry, Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan

Abstract

Two new bis-secoiridoid glycosides, named ilicifoliosides A and B, were isolated from the leaves of Osmanthus ilicifolius. Their structures have been determined by 1D and 2D NMR analysis.

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Note | Special issue | Vol 74, No. 1, 2007, pp. 943 - 950
Published online: 28th August, 2007
DOI: 10.3987/COM-07-S(W)14
A Novel Reductive Amino-Cyclization Method and Its Application for the Total Syntheses of (±)-Aurantioclavine and (±)-Lophocerine

Masanori Somei* and Fumio Yamada

*Division of Pharmaceutical Sciences, Graduate School of Natural Science and Technology, Kanazawa University, Kakuma, Kanazawa, Ishikawa 920-1192, Japan

Abstract

A novel reductive amino-cyclization method for the synthesis of azacycloalkanes is developed. Its versatility is proved by the total syntheses of (±)-aurantioclavine (1), an ergot alkaloid, and (±)-lophocerine (2), a cactus alkaloid, as examples of azepane and piperidine skeletons, respectively.

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Note | Special issue | Vol 74, No. 1, 2007, pp. 951 - 960
Published online: 20th September, 2007
DOI: 10.3987/COM-07-S(W)17
Synthesis of 4-(Azuleno[b]indolyl)-3-buten-2-ones by Intramolecular Tropylium Ion-Mediated Furan Ring-Unravelled Reaction

Mitsuko Nishiura, Ikuko Ueda, and Kimiaki Yamamura*

*Department of Chemistry, Faculty of Science, Kobe University, Nada-Ku, Kobe 6557-8501, Japan

Abstract

4-(1-Benzenesulfonyl-6-azuleno[1,2-b]indolyl)-3-buten-2-one (1) and 4-(1-benzenesulfonyl-11-azuleno[2,1-b]indolyl)-3-buten-2-one (2) were synthesized from 1-benzenesulfonyl-3-(5-methylfuryl)-2-tropylioindole (10) and 1-benzenesulfonyl-2-(5-methylfuryl)-3-tropylioindole (14), respectively. The synthetic method is based on furan ring-unraveled reaction by the intramolecular electrophilic attack of the tropylium ion. 4-(6-Azuleno[1,2-b]indolyl)-3-buten- 2-one (3) and 4-(11-azuleno[2,1-b]indolyl)-3-buten-2-one (4) could be easily obtained from 1 and 2, respectively. Treatment of 3 and 4 with iodomethane gave N-methyl derivatives, 4-(1-methyl-6-azuleno[1,2-b]indolyl)-3-buten-2-one (5) and 4-(1-methyl-11-azuleno[2,1-b]indolyl)-3-buten-2-one (6), respectively, in moderated yield. The compounds, 1, 2, 3, 4, 5, and 6, which include the novel tetracyclic π conjugated azulene nuclei, are the azuleno[b]indole analogues of benzalacetone.

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Note | Special issue | Vol 74, No. 1, 2007, pp. 961 - 968
Published online: 26th October, 2007
DOI: 10.3987/COM-07-S(W)26
■ OneOne-Pot Synthesis of Dibenzofuran-1,4-diones

Tetsuya Takeya,* Hiromu Kondo, Kazuho Tomita, Iwao Okamoto, Nobuyoshi Morita, and Osamu Tamura*

*Showa Pharmaceutical University, 3-3165, Higashi-tamagawagakuen, Machida, Tokyo 194-8543, Japan

Abstract

One-pot synthesis of dibenzofuran-1,4-diones 8 from 4-methoxyphenols (or 4-methoxy-1-naphthols) 4 was achieved by oxidative dimerization over a semiconductor in heated, O2-saturated toluene, followed by selective monodemethylation, and oxidative cyclization.

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Note | Special issue | Vol 74, No. 1, 2007, pp. 969 - 976
Published online: 19th October, 2007
DOI: 10.3987/COM-07-S(W)35
Huncaniterine A, a New Bisindole Alkaloid from Hunteria zeylanica

Khalit Mohamad, Tomoko Suzuki, Yuki Baba, Kazumasa Zaima, Yosuke Matsuno, Yusuke Hirasawa, Mat Ropi Mukhtar, Khalijah Awang, A. Hamid A. Hadi, and Hiroshi Morita*

*Faculty of Pharmaceutical Sciences, Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan

Abstract

A new bisindole alkaloid, huncaniterine A (1) consisting of corynantheine-type and aspidospermane-type skeletons, has been isolated from the bark of Hunteria zeylanica (Apocynaceae) and the structure was elucidated on the basis of spectroscopic data. Huncaniterine A (1) exhibited a vasorelaxant activity on isolated rat aorta ring.

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