Regular Issue

Vol. 22, No. 4, 1984

36 data found. 1 - 30 listed Next Last
Communication | Regular issue | Vol 22, No. 4, 1984, pp.657-661
Published online:
DOI: 10.3987/R-1984-04-0657
Acrolein as a Synthon for Pyrimidinic Compounds. Reaction with Benzamidine

Alexander Weis,* Felix Frolow, Dov Zamir, and Michael Bernstein

*Department of Organic Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel

Abstract

Depending on the reaction conditions, acrolein (stabilized by hydroquinone) reacts with benzamidine to give selectively tetrahydropyrimidine (4), dihydropyrimidine (5) and pyrimidine (6) in high yields.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.663-666
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DOI: 10.3987/R-1984-04-0663
Thermal Rearrangement of 2-(2-Furylmethoxy)tropones

Hitoshi Takeshita* and Hiroaki Mametsuka

*Instituete of Advanced Material Study, Kyushu University, 6-1, Kasuga-koen, Kasuga 816-8580, Japan

Abstract

Furfuryl ethers of tropolone and 4- and 5-isopropyltropolones afforded 3-(2-methyl-3-furyl)-, 3-(2-furylmethyl)-, 5-(2-furylmethyl)-, and 5-(5-methyl-2-furyl)tropolone derivatives. Although most of the thermolysates were structurally indistinguishable to the 3,3- or 5,5-sigmatropic products, the deuterium-labelling experiment proved all the pyrolysates to be intermolecular reaction products.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.667-669
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DOI: 10.3987/R-1984-04-0667
The Structure of Graciline, a New Diterpeoid Alkaloid from Delphinium Gracile

Antonio G. González,* Gabriel de la Fuente, Matías Reina, and Isabel Timón

*Instituto de QUímica Orgánica, Instituto de Productos Naturales Orgánicos, C. S. I. C./ Unversidad de La Laguna, La Laguna, Tenerife, Canary Islands, Spain

Abstract

Besides hetisinone, 13-acetylhetisinone, cardiopetamine, and atisinium chloride, a new diterpenoid alkaloid graciline was isolated from Delphinium gracile, and its structure elucidated. The 13C-NMR chemical shifts for graciline, cardiopetaline and cardiopetalidine are presented.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.671-673
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DOI: 10.3987/R-1984-04-0671
The Uncatalyzed Cycloaddition of a Siloxydiene to N-Acylimines. The Synthesis of 4-Pyridones

Rudolph A. Abramovitch* and Lames R. Stowers

*Department of Chemistry, Clemson University, Clemson, SC 29631, U.S.A.

Abstract

The (4 + 2) cycloaddition of 1-methoxy-3-trimethylsilyloxy-1,3-butadiene to cyclic and open-chain N-sulfonylimines leads to 5,6-dihydro-1,1-sulfonyl-4-pyridones. The presence of a good leaving group at C-6 leads to elimination and the formation of the corresponding 4-pyridone.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.675-679
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DOI: 10.3987/R-1984-04-0675
Regiocontrolled Cyclisation to the Isomeric Dipyridazino[4,5-b:4‘,5‘-e][1,4]thiazines — Competence and Performance of Benzylamino and Thioether Functions on the 3(2H)-Pyridazinones as Regiocontrolling Elememts

Kenji Kaji, Hiromu Nagashima, and Hirohisa Oda*

*Gifu Pharmaceutical University, 6-1 Mitahora-higashi 5-chome, Gifu 502-8585, Japan

Abstract

The 5,5’-thioethers (5a-c) perform a regiocontrolled cyclisation affording either the 10H-dipyridazino[1,4]thiazine-1,9-diones (1’a-c) (by Ullmann mode) or the 10-benzyl derivatives of 1,6-dione isomers (2a-c) (via Smiles rearrangement), only depending on the acidity of media employed. The 4,5’-thioethers (6a-c) exhibit also the regiospecific control to give exclusively the 10H-dipyridazino[1,4]thiazine-1,6-diones (2’a-c) in acidic conditions or the 10-benzyl-4,6-dione isomers (3a-c) in basic conditions, respectively. Some principal features of the regiocontrolled cyclisation are discussed.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.681-686
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DOI: 10.3987/R-1984-04-0681
Preparation and Characterization of Some Unsymmetrical Thiadiphosphiranes

Masaaki Yoshifuji,* Katsuhiro Shibayama, and Naoki Inamoto

*Department of Chemistry, School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan

Abstract

Unsymmetrical diphosphenes 1b-d were monosulfurized and thermally or photochemically cyclized successively to give the corresponding unsymmetrical thiadiphosphiranes 3b-d. The spin-spin coupling constants 1Jpp in the thiadiphosphirane ring system were directly observed for the first time.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.687-689
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DOI: 10.3987/R-1984-04-0687
A New Synthesis of 1,2-Dihydro-β-carbolin-4(3H)-ones

Charles Mackey and Roger D. Waigh*

*Department of Chemistry, University of Manchester, Oxford Road, Manchester, M13 9PL, U.K.

Abstract

Aminonitriles derived from 3-aminomethylindoles are rearranged by treatment with polyphosphoric acid at 80°C or sulphuric acid at 0°C, to give 1,2-dihydro-β-carbolin-4(3H)-ones.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.691-694
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DOI: 10.3987/R-1984-04-0691
Hongconin, a New Naphthalene Derivative from the Rhizome of Eleutherine amaricana (Hong-Cong)

Chen Zhengxiong (Masao Chin),* Huang Huizhu, Wang Chengrui, Li Yuhui, Ding Jianmi, Ushio Sankawa, Hiroshi Noguchi, and Yoichi Iitaka

*Tsumura Laboratory, 1-9-9, Izumihonncho, Komae-shi, Tokyo 201, Japan

Abstract

A new naphthalene derivative, hongconin was isolated from the rhizome of Eleutherine americana Merr. et Heyne (Iridaceae) (Chinese name; Hong-Cong) along with three known naphthalene derivatives (1-3). The structure of hongconin was determined to be (4) by spectral and X-ray analyses.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.695-699
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DOI: 10.3987/R-1984-04-0695
A Facile Synthesis of Novel 3-(1,2,4-Triazole-5-yl)methylene-2-oxo-1,2,3,4-tetrahydroquinoxalines and Their Related Compounds

Yoshihisa Kurasawa,* Kumi Suzuki, Shoko Nakamura, Kayano Moriyama, and Atsushi Takada

*School of Pharmaceutical Sciences, Kitasato University, Shirokane, Minato-ku, Tokyo 108-8641, Japan

Abstract

Various new type of triazoles, 3-(1,2,4-triazol-5-yl)methylene-2-oxo-1,2,3,4-tetrahydroquinoxalines (4-7) and related compounds (8,9), were synthesized from 3-hydrazinocarbonylmethylene-2-oxo-l,2,3,4-tetrahydroquinoxaline (1).

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.701-703
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DOI: 10.3987/R-1984-04-0701
Novel Synthesis and 1,3-Dipolar Cycloaddition Reaction of Pyridinium N-Methylide

Yasuyoshi Miki,* Hiroko Hachiken, Shoji Takemura, and Masazumi Ikeda

*Faculty of Pharmaceutical Sciences, Kinki University, 3-4-1, Kowakae, Higashi-Osaka 577-8502, Japan

Abstract

Pyridinium N-methylide, generated in situ by treating N-(trimethylsilylmethyl)pyridinium triflate with fluoride ion, was found to react with dimethyl acetylenedicarboxylate to give dimethyl indolizine-1,2-dicarboxylate. Similarly, the N-methylides derived from quinoline and isoquinoline gave the corresponding indolizine derivatives. With N-phenylmaleimide and (E)-1,2-dibenzoylethylene, however, pyridinium N-methylide afforded N-phenylitaconimide and 2,3-dibenzoylpropene, respectively.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.705-708
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DOI: 10.3987/R-1984-04-0705
Addition Reaction of Indolizine Derivatives with Dimethyl Acetylenedicarboxylate

Yoshiro Yamashita,* Daisuke Suzuki, and Mitsuo Masumura

*Faculty of Engineering, University of Tokushima, Minamijosanjima-cho, Tokushima 770-8506, Japan

Abstract

Indolizine derivatives reacted 1 with dimethyl acetylenedicarboxylate to give 1:1 adducts 2-6. In some cases 1:2 adducts 7 were obtained from which cycl[4.3.2]azine derivatives 11 were synthesized by dehydrogenation. The addition reaction was dependent on the substituents and solvents employed.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.709-712
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DOI: 10.3987/R-1984-04-0709
A Convenient Synthesis of a Linear Pyranoisoflavone: Syntheses of Elongatin and Its Angular Isomer

Masao Tsukayama,* Yukihisa Iguchi, Tokunaru Horie, Mitsuo Masumura, and Mitsuru Nakayama

*Department of Chemical Science and Technology, Faculty of Engineering, University of Tokushima, Minamijosanjima-cho, Tokushima 770-8506, Japan

Abstract

Linear 4’,5-dihydroxy-2’,5’-dimethoxy-2”,2”-dimethyldihydropyrano[5”,6”-g]isoflavone, which had been prepared from 6-acetyl-5-benzyloxy-7-hydroxy-2,2-dimethylchroman via four steps, was dehydrogenated with DDQ to give elongatin. Its angular isomer was also synthesized from 6-acetyl-7-benzyloxy-5-hydroxy-2,2-dimethylchroman in a similar manner.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.713-716
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DOI: 10.3987/R-1984-04-0713
A Simple Synthesis of Bicyclomycin Skeleton

Akira Sera,* Kuniaki Itoh, Hiroshi Yamada, and Ryuichi Aoki

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

Abstract

The bicyclomycin skeleton(7,9-dibenzyl-5-methylene-7,9-diaza-2-oxabicyclo[4.2.2]decane-8,10-dione) was synthesized from 3,6-dimethoxy-2,5-piperazinedione by 6 steps in a 32% yield.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.717-720
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DOI: 10.3987/R-1984-04-0717
X-Ray Crystallographic Structures of 9-Methyl-3-oxa-2,6,8-triphenyl-5-azatricyclo[4,2,1,02,6]non-7-ene 6-Hydroxy-1,6,7-triphenylazabicyclo[3,3,0]octa-2,7-diene and 6-Hydroxy-4-methyl-1,6,7-triphenylazabicyclo[3,3,0]oct-7-ene: Products Formed by Rearrangements of N-Vinylpyridinium Pseudobases

Gus Palenik, Danuta Pyzalska, Hossein Aghabozorg, Olga Rubio, and Alan R. Katritzky*

*Center for Drug Discovery, College of Pharmacy, University of Florida, Gainesville, Florida 32611-7200, U.S.A.

Abstract

The reaction of hydroxide ion with 1-vinyl or 1-propenyl-2,4,6- triphenylpyridinium salts produces an unusual rearrangement to 3-oxa-2,6,8-triphenyl-5-azabicyclo[4,2,1,02,6 ]non-7-ene or the corresponding 9-methyl derivative as shown by spectroscopic and X-ray crystallographic techniques.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.721-724
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DOI: 10.3987/R-1984-04-0721
Photo-sensitized Oxygenation of Monocyclic 1H-1,3-Diazepines

Jyoji Kurita, Hirokazu Kojima, and Takashi Tsuchiya*

*School of Pharmacy, Hokuriku University, 3-Ho, Kanagawa machi, Kanazawa 920-1181, Japan

Abstract

The sensitized photooxygenation of monocyclic 1H-1,3-diazepines (1a-c) affords fragment products (2) to (7), which may be derived from the corresponding 4,7-endoperoxides (8) or the 4,5-dioxetanes (9) initially formed. The other possible dioxides and their decomposition products are not detected.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.725-728
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DOI: 10.3987/R-1984-04-0725
A Base-catalyzed Stereospecific Epoxidation with α-Azohydroperoxides

Takahiro Tezuka* and Masaaki Iwaki

*Department of Chemistry, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki, 305-8571, Japan

Abstract

A new stereospecific epoxidation with the α-azohydroperoxide (1) is reported. α-Azohydroperoxides (1a - 1d) epoxidized cis- and trans-stilbenes stereospecifically in the reaction catalyzed by pyridine or sodium hydroxide. Similarly, cyclohexene, norbornylene, and cis-β-methylstyrene all were epoxidized by 1a - 1d in good to high yields in basic media. Reactive species of the epoxidation are discussed.

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Communication | Regular issue | Vol 22, No. 4, 1984, pp.729-731
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DOI: 10.3987/R-1984-04-0729
A Short and Novel Synthesis of the Pyrrolizidine Alkaloids, (±)-Supinidine and (±)-Trachelanthamidine

Tetsuji Kametani,* Kimio Higashiyama, Hirotaka Otomatsu, and Toshio Honda

*Hoshi University, 2-4-41 Ebara, Shinagawa-ku, Tokyo 142-8501, Japan

Abstract

The effective and short syntheses of the pyrrolizidine alkaloids, (±)-trachelanthamidine (8) and (±)-supinidine (12) were described.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.733-744
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DOI: 10.3987/R-1984-04-0733
Tryptophan Derived Pyridinium Salts: Preparation, Reductive Cyanation and Addition Reactions

Ari Koskinen and Mauri Lounasmaa*

*Laboratory of Organic Chemistry, Helsinki University of Technology, P.O. Box 6100,FIN-02015 HUT, Espoo, Finland

Abstract

Tryptophan derived pyridinium salts 8 can be prepared from methyl 2-tosyloxy-3-(3-indolyl)propionate 6d. The salt formation was usually accompanied by rearrangement in the indole side chain. Behaviour of the pyridinium salts under reductive cyanation conditions and in nucleophilic addition reactions were studied.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.745-748
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DOI: 10.3987/R-1984-04-0745
Bromination of 6-Acetyl-2-ethoxy-4H-1,3,2-benzodioxaphosphorin 2-Sulfide in Methanol and Carbon Tetrachloride

Rohit Chandra Borthakur, Naleen Borthakur, and Ramesh Chandra Rastogi*

*Division of Drug and Pharmaceutical Chemistry, Regional Research Laboratory, Jorhat 785 006, Assam, India

Abstract

The reaction of 6-acetyl-2-ethoxy-4H-1,3,2-benzodioxaphosphorin 2-sulfide 12 with methanol-bromine gave 4-hydroxy-3-(methoxymethyl)acetophenone 45 , ω-bromo-4-hydroxy-3-(methoxymethyl)acetophenone 5 and 5, ω-dibromo-4-hydroxy-3-(methoxymethyl)acetophenone 6; reaction of 1 with carbon tetrachloride-bromine gave only 6-(ω-bromo)acetyl-2-ethoxy-4H-1,3,2-benzodioxaphosphorin 2-sulfide 2 and 6-(ω, ω-dibromo)acetyl-2-ethoxy-4H-1,3,2-benzodioxaphosphorin 2-sulfide 3. The possible reaction mechanism is discussed.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.749-761
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DOI: 10.3987/R-1984-04-0749
Enzymatic "in vitro" Reductions of Ketones. Part 12. Reduction of 1-Alkyl-4-piperidones in an Ethanol-NAD+-HLAD-system

Jaymes Van Luppen, Jozef Lepoivre, Guy Lemière, and Frank Alderweireldt

*Labratory of Organic Chemistry, University of Antwerp (RUCA), Groenenborgerlaan 171, B-2020 Antwerp, Belgium

Abstract

The steady state initla1 rate equation for a ketone-ethanol-NAD+-HLAD recycling system is checked for 1-n-butyl-4-piperidone. All reaction parameters are discussed in order to optimize the reduction of this substrate. For a series of 1-alkyl-4-piperidones the thermodynamic activation parameters for the reduction in this system are determined and discussed.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.763-766
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DOI: 10.3987/R-1984-04-0763
Ring Transformation of 2,3-Disubstituted 4(3H)-Pyrimidinethiones with Malononitrile

Akira Katoh,* Yoshimori Omote, and Choji Kashima

*Department of Chemistry, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki, 305-8571, Japan

Abstract

2,3-Disubstituted 4(3H)-pyrimidinethiones (Ia-d) underwent the ring transformation with malononitrile in the presence of sodium ethoxide to give N-substituted 2-amino-3-cyano-4(1H)-pyridinethiones (IIa-d) in high yields.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.767-772
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DOI: 10.3987/R-1984-04-0767
1,2,3,5,6,10b-Hexahydropyrrolo[2,1-a]isoquinolines. Preparation and Stereochemistry of 3-Benzyl Derivatives

Joan Bosch,* Esther Mestre, Josep Bonjoch, Francisco López, and Ricardo Grandos

*Laboratory of Organic Chemistry, Faculty of Pharmacy, University of Barcelona, Av. de Joan XXIII, s/n, 08028 Barcelona, Spain

Abstract

The preparation of cis- and trans-3-benzyl-1,2,3,5,6,10b-hexahydropyrrolo[2,1-a]isoquinolines 1 and 2 and the preferred conformation of the indolizidine ring system of these compounds are reported.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.773-778
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DOI: 10.3987/R-1984-04-0773
Preparation of Some Stable and Transient 1,3-Oxazolium-4-olates

Makhluf J. Haddadin* and Hana T. Tannus

*Department of Chemistry, American University of Beirut, Beirut, Lebanon

Abstract

A number of mandelanilides (6) were prepared and oxidized with barium manganate to phenylglyoxanilides (7). The latter were converted to N-benzoylphenylglyoxanilides which, upon heating with triethyl phosphite, gave the corresponding 1,3-oxazolium-4-olates (2). 1,3-Oxazolium-4-olates 2f,g,o were isolated as colored solids whereas the rest of these mesoionic compounds (Table II) showed transitory existence in solution.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.779-783
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DOI: 10.3987/R-1984-04-0779
Modified Bleomycins. Synthesis of New Bleomycins via Reaction of Demethyl-BLM A2 with Bromoacetyl Derivatives

Wilhelmus J. Vloon, Cornelis Kruk, Upendra K. Pandit,* Hendricus P. Hofs, and John G. McVie

*Organic Chemistry Department, University of Amsterdam, Nieuwe Achtergracht 129, 1018 WS Amsterdam, The Netherlands

Abstract

Reaction of demethyl-BLM A2 with bromoacetyl derivatives leads to the corresponding sulfonium salts which constitute a new class of biologically active bleomycins.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.785-790
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DOI: 10.3987/R-1984-04-0785
Synthesis of Cyclo-N-methyl-L-tyr-N-methyl-L-tyr-D-ala-L-ala-O,N-dimethyl-L-tyr-L-ala, a Cyclic Hexapeptide Related to the Antitumor Agent Deoxybouvardin

Robert B. Bates,* Susan L. Gin, Mark A. Hassen, Victor J. Hruby, Kim D. Janda, George R. Kriek, Jon-Pierre Michaud, and Daniel B. VIne

*Department of Chemistry, The University of Arizona, Tucson, Arizona 85721, U.S.A.

Abstract

A synthesis of the title cyclic hexapeptide is described. Its lack of antitumor activity shows That the 14-membered ring of deoxybouvardin is needed for activity. Efforts to oxidatively couple its phenolic groups failed to give deoxybouvardin.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.791-794
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DOI: 10.3987/R-1984-04-0791
Convenient Synthesis of Benzi[b]tropones Fused with Indolizines or Indoles by Reaction of 2-Phenyl-3-vinyl Substituted Derivatives with Polyphosphoric Acid

Yoshiro Yamashita,* Daisuke Suzuki, and Mitsuo Masumura

*Faculty of Engineering, University of Tokushima, Minamijosanjima-cho, Tokushima 770-8506, Japan

Abstract

Reaction of 2-phenyl-3-(2-ethoxycarbonylvinyl)indolizine derivatives with polyphosphoric acid gave 8H-benzo[6,7]cyclohept[1,2-b]indolizin-8-ones 2 by an intramolecular acylation reaction. Reaction of 2-phenyl-3-(2-ethoxycarbonylvinyl)indole derivatives gave 5H,10H-benzo[6,7]cyclohept[l,2-b]indol-10-ones 7.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.795-796
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DOI: 10.3987/R-1984-04-0795
Reinvestigation of the Reaction of N,N-Dimethyl-3-methylbenzenamine with Pyridine in the Presence of Benzpyl Chloride

Baldev Singh

*Sterling Winthrop Pharmaceuticals Research Division, Rensselaer, New York, 12144, U.S.A.

Abstract

The reaction of N,N-dimethyl-3-methylbenzenamine with pyridine in the presence of benzoyl chloride gave N,N-dimethyl-3-methyl-4-(4-pyridinyl)benzenamine which was demethylated with pyridine hydrobromide to afford 3-methyl-4-(4-pyridinyl)benzenamine.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.797-801
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DOI: 10.3987/R-1984-04-0797
A Practical One Pot Synthesis of 4-Alkoxy-3-formylindoles

Masanori Somei,* Fumio Yamada, Masako Kunimoto, and Chikara Kaneko

*Faculty of Pharmaceutical Sciences, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan

Abstract

A simple and regioselective one pot synthetic method of 4-methoxy-, 4-benzyloxy-, and 4-ethoxy-3-formylindoles from 3-formylindole is described.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.803-806
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DOI: 10.3987/R-1984-04-0803
Reduction of the Herbicide Diquat with Sodium Borohydridenickel (II) Chloride: Structure of the Two Isomeric Perhydro-8a,10a-diazaphenanthrenes

Shigeo Ukai,* Shozo Kawase, Susumu Kanno, Tadashi Kiho, Masaru Kido, and Iwao Miura

*Gifu Pharmaceutical University, 6-1 Mitahora-higashi 5-chome, Gifu 502-8585, Japan

Abstract

The stereochemistry of isomeric perhydro-8a,10a-diazaphenanthrenes(2 and 3) obtained by sodium borohydride-nickel (II) chloride reduction of the herbicide, diquat (1), was confirmed by X-ray crystallographic analysis of the hydrobromide of 2, and of the hydrochloride of partially reduced product, 1,4,4a,4b,5,8,9,10-octahydxo-8a,10a-diazaphenanthrene(6), which is converted with ease to 3.

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Report | Regular issue | Vol 22, No. 4, 1984, pp.807-811
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DOI: 10.3987/R-1984-04-0807
Studies on Imidazole Deivatives and Related Compounds. Synthesis of 5-Oxo-5H-imidazo[2,1-b]pyrido[3,2-e][1,3]thiazine, a New Ring System

Elena Belgodere, Ricardo Bossio, Roberto Cencioni, Stefano Marcaccini, and Roberto Pepino*

*CNR, Centro di Studio Sulla Chimica e la Struttura dei Composti Eterociclici e lolo Applicazioni, c/o Dipartimento di Chimica Organica "Ugo Schiff", Università di Firenze, Via Gino Capponi 9, I-50121 Firenze, Italy

Abstract

The reaction between 2-chloronicotinlc acid chloride (I) and 1-benzyl-2-mercapto-1H-imidazile-5-carboxylic acid (IIa) or its ethyl ester (IIb) led to the formation of 5-oxo-5H-imidazo[2,1-b]pyrido[3,2-e][1,3]thiazine-3-carboxylic acid (VIIa) or its ethyl carboxylate (VIIb) respectively. This new ring system undergoes ring-opening reactions by nucleophiles giving 2-(2-imidazolylthio)pyridne derivatives.

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