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
Shigehiko Sugasawa's Special Issues, Vol. 8, No. 1, 1977
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■ A Novel Synthesis of 5- or 13-Oxygenated Tetrahydroprotoberberines
Hiroshi Hara, Machiko Hosaka, Osamu Hoshino, and Bunsuke Umezawa*
*Faculty of Pharmaceutical Sciences, Science University of Tokyo, 2641 Yamazaki, Noda, Chiba 278-8510, Japan
Abstract
In order to introduce O-functional groups at the 5- or 13-position in tetrahydroprotoberberine, we tried lead tetraacetate oxidation of (±)-2-hydroxy-3, 10,11-trimethoxy (3)- or (±)-10-hydroxy-2,3,11-trimethoxy (12)-tetrahydroprotoberberine, a moiety of which was 1,2,3,4-tetrahydro-7-hydroxy-6-methoxyisoquinoline convertible to the corresponding 4,7-diacetate via p-quinol acetate.
(±)-2-Phenol (3) yielded a p-quinol acetate (4), which was transformed to several 5-oxygenated tetrahydroprotoberberines (6, 7, 8, 9, 10, and 11). Similarly, some 13-oxygenated derivatives (14, 15 and 16) were prepared from (±)-10-phenol (12).
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■ A Biogenetic-type Asymmetric Synthesis of Optically Active Amaryllidaceae Alkaloids: (+)- and (-)-Galanthamine from L-Tyrosine
Kimihiro Shimizu, Kiyoshi Tomioka, Shun-ichi Yamada, and Kenji Koga*
*Faculty of Pharmaceutical Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
Abstract
A biogenetic-type asymmetric synthesis of optically active galanthamine (4) from L-tyrosine (L-1) was achieved via the intramolecular phenolic oxidative coupling of norbelladine derivative (5) followed by asymmetric cyclization. Enantiomeric interconversion of narwedine derivative (7) is also described.
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■ Synthetic Studies on β-Lactam Antibiotics. Part 3. Synthesis of 3-Trifluoromethyl Cephalosporins from Penicillins
Sadao Yamamoto, Nobuhiro Haga, Tsutomu Aoki, Sadao Hayashi, Hiroshi Tanida, and Wataru Nagata*
*Shionogi Research Laboratories, Shionogi & Co. Ltd., Fukushima-ku, Osaka 553-0002, Japan
Abstract
A new synthetic route to 3-trifluoromethyl cephalosporins from penicillin V has been developed. A key intermediate, diphenylmethyl α-{(1R,5R)-3-phenoxymethyl-7-oxa-4-thia-2,6-diazabicyclo[3.2.0]hept-2-en-6-yl}glycolate (4), was easily obtained by ozonolysis of the known olefin 1 and by zinc-acetic acid reduction of its ozonide. Acid cleavage of the thiazoline ring of 4 followed by alkylation with 1,1,1-trifluoro-3-bromoacetone gave compound 6. Reaction of 6 with thionyl chloride and successive treatment with triphenylphosphine afforded the corresponding phosphorane 7, which afforded a desired 3-trifluoromethyl-3-cephem compound 8 by intramolecular Wittig cyclization. The new cephalosporins showed interesting in vitro and in vivo antibacterial activities.
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■ Studies on Indolizine Derivatives. New Synthetic Mothods of Azacycl[3.2.2]azine Derivatives. XI
Kenji Kurata, Hiroyoshi Awaya, Yoshinori Tominaga, Yoshiro Matsuda, and Goro Kobayashi*
*Faculty of Pharmaceutical Sciences, Nagasaki University, 1-14, Bunkyo-machi, Nagasaki 852-8521, Japan
Abstract
N-Bridged 10Π electron ring systems, azacycl[3.2.2]azine derivatives (II, III) were obtained by the photochemical reaction of azaindolizine derivative (I), or by the reaction of I with N-bromosuccinimide (NBS).
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■ Displacement Reactions of 2-Alkylsulfonyl-4-chloropyromidine Derivatives with Nucleophiles
Tadahiro Sawayama, Ryuichi Yamamoto, Hiroaki Kinugasa, and Haruki Nishimura*
*Dainippon Pharmaceutical Co., LTD., Enoki 33-94, Suita, Osaka 564, Japan
Abstract
The displacement reactions of 4-chloro-2-ethylsulfonyl-6-phenyl-, 4-chloro-2-ethylsulfonyl- and 4-chloro-6-methyl-2-methylsulfonyl-pyrimidine with ammonia gave the corresponding 4-alkylsulfonyl-2-aminopyrimidine derivatives in which the alkylsulfonyl groups migrated from the 2-position to the 4-position. In addition, it was found that the relative ease of displacement of sulfonyl group versus chloro group in the nucleophilic substitution of 2- and 6-alkylsulfonyl-4-chloropyrimidine derivatives depended on nucleophiles.
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■ Reactions and Synthetic Applications of β-Ketosulfoxides VIII. Synthesis of 1,1-Dimethylthio-1,2,3,4-tetrahydrocarbazol-2-ones and Their 1,2-Carbonyl Transposition
Yuji Oikawa* and Osamu Yonemitsu
*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
β-Ketosulfoxides (9, 10, 11), prepared from indolepropionic acid esters (6, 7, 8) with the K or Li salt of methyl methylthiomethyl sulfoxide, undergo the acid-catalyzed cyclization to yield 1,1-dimethylthio-1,2,3,4-tetrahydrocarbazol-2-ones (14, 15, 16), which were efficiently converted to 1,2,3,4-tetrahydrocarbazol-1-ones (22, 23, 25, 29) through the (alkylative) 1,2-carbonyl transposition. A pyrrolepropionic acid ester (12) similarly gave a 4,5,6,7-tetrahydroindol-4-one (31) via 4,4-dimethylthio-4,5,6,7-tetrahydroindol-5-one (17).
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■ Reactions of 3-Chloroindolenines with Some Nucleophiles
Yasumitsu Tamura,* Moon Woo Chun, Hiroshi Nishida, and Masazumi Ikeda
*Faculty of Pharmaceutical Sciences, Osaka University, 1-6 Yamadaoka, Toyonaka, Osaka 560-0043, Japan
Abstract
The behavior of 3-chloro-2,3-diphenyl- and 3-chloro-3-methyl-2-phenyl-indolenines towards some nucleophiles in acetic acid was examined. Nucleophiles such as N3- and AcO- underwent irreversible nucleophilic attack, possibly by SN1 mechanism, at the 3-position of the 3-chloroindolenines to give 3-azido- and 3-acetoxy-indolenines, while the nucleophiles such as I-, PhSH, Ph3P, Br-, and SCN- reverted the 3-chloroindolenines to the parent indoles by attacking the chlorine atom. Bromine and thiocyanogen (or their equivalents) thus formed underwent further electrophilic attack at the 6-position of the indoles to give β-bromo- and 6-thiocyanato-indoles, respectively. The above results are discussed in terms of the HSAB principle.
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■ Synthesis of Pyrazolone Derivatives. XXXII. Studies on (5S,8R)-8,9,9-Trimethyl-5,6,7,8-tetrahydro-5,8-methano-1,2,3-banzotriazine
Isoo Ito,* Noriichi Oda, Shin-ichi Nagai, and Yoshihisa Kudo
*Faculty of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
Abstract
Oxidation of 2-amino-4,7-methanoindazole (2) resulted in ring expansion to afford 5,8-methano-1,2,3-benzotriazine (3) which showed prominent central stimulation in mice. Irradiation of 3 provided 3-ethynylcyclopentanecarbonitrile (4).
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■ New Prostaglandin Synthon from an 4-Oxa-tricyclo[4.3.0.03,7]-non-8-ene System. A Total Synthesis of (±)-Prostaglandin F2a
Seiichi Takano,* Noboru Kubodera, Hiromitsu Iwata, and Kunio Ogasawara
*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan
Abstract
The C-9 tricyclic heterocycle (1) is shown to be a new starting material for a synthesis of (±)-prostaglandin F2α through the C-9 acetylenic intermediate (10).
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■ The Fischer Indole Synthesis with Formic Acid. III. The Reaction with 2-Substituted Adipoins
Takeshi Wakamatsu,* Hiromu Hara, and Yoshio Ban
*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
The Fischer indolization of 2-substituted adipoins was effected with formic acid to afford 1-substituted tetrahydrocarbazoles (9) and the corresponding carbazoles (10).
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■ Syntheses of Medium-sized Keto-lactam Systems by the Photo-ring-enlargement of N-Substituted Alicyclic Imides
Yuichi Kanaoka,* Haruo Okajima, and Yasumaru Hatanaka
*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
Synthetic application of the photo-ring-expansion reaction of N-substituted alicyclic imides 1 was studied and a variety of seven- and eight-membered keto-lactam systems 2 were photochemically synthesized from succinimides and glutarimides.
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■ Photochemistry of Succinimides with an Ether or a Thioether in Their Side-chains. γ- and δ-Hydrogen Abstraction
Hideo Nakai, Yasuhiko Sato,* Tomishige Mizoguchi, Michio Yamazaki, and Yuichi Kanaoka*
*Organic Chemistry Research Laboratory, Tanabe Seiyaku Co.Ltd., 2-2-50, Kawagishi, Toda, Saitama 335-8505, Japan
Abstract
Upon irradiation certain N-β-sec-alkaxyalkyl-substituted succinimides 4 afforded a pyrrolo[1,2-c]oxazole ring system 5, δ-hydrogen trasfer products, in moderate yields. On the other hand, the thioether analogs 11, 17 gave mixtures of γ-products (13, 14, 15, 18) and γ-products (16, 19), in low yields.
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■ Quaternization of Pyrizine Monoxides, and Reduction of 1-Methyl-4-oxidopyrizinium Iodides with Sodium Borohydride
Akihiro Ohta,* Mayumi Matsunaga, Noriko Iwata, and Tokuhiro Watanabe
*Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
Quaternization of some methyl- and phenyl-pyrazizne 1-oxides with methyl iodide was investigated. The 1-methyl-4-oxidopyrazinium iodides obtained were treated with sodium borohydride to give N-hydroxypiperazines. The effect of substituents on the quaternization and reduction was discussed.
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■ Synthesis Utilizing β-Carbonyl System. IV. A Novel Cyclization of 1,9-Diimino-3,7-dicarbonyl and -3,5,7-tricarbonyl Compounds
Ikuo Iijima, Michihiko Miyazaki, Naomasa Taga, and Tadasu Tanaka*
*Biological and Chemical Research Laboratories, Tanabe Seiyaku Co.Ltd., 2-2-50, Kawagishi, Toda, Saitama 335-8505, Japan
Abstract
Bis-(3-methyl-5-isoxazolylmethyl)ketone (1) was converted into 1,9-diimino-3,7-dicarbonyl compounds (3 and 7), which were cyclized to 8-isoquinolinols (5 and 10) by hydrochloric acid in high yields. The compound (12) containing a sterically crowded 1,9-diimino-3,5,7-tricarbonyl system was prepared from the methyl analogue (11) of the ketone (1). The cyclization of 12 afforded the 4-pyridone (13) exclusively.
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■ Synthesis and Some Reactions of Benzo[f]quinoline-5,6-oxide
Yoshiyasu Kitahara, Koichi Shudo, and Toshihiko Okamoto*
*Faculty of Pharmaceutical Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
Abstract
Benzo[f]quinoline-5,6-oxide, a possible active metabolite of benzo[f]quinoline, was prepared and the chemical reactions of the oxide were examined.
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■ Reaction of Arylhydroxamic Acids with Benzene
Yasuyuki Endo, Toshiharu Ohta, Koichi Shudo, and Toshihiko Okamoto*
*Faculty of Pharmaceutical Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113, Japan
Abstract
Arylhydroxamic acids were reacted with benzene in the presence of trifluoromethanesulfonic acid to form aminobiphenyl derivatives. This reaction was applied to an intramolecular cyclization for the synthesis of dibenz(b,d)azepine and dibenz(b,d)azocine derivatives.
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■ Synthesis of 4-Substituted Indole Derivatives
Tatsuo Nagasaka, Tohru Tuge, and Sadao Ohki*
*Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
A general synthetic method of 4-substituted indoles was examined. The Fischer indolization of phenylhydrazones (2, 3, 7, and 8) having chlorine on ortho position gave 7-chloro-4-substituted indoles (4, 9, and 10), which were converted to 4-substituted indoles (5 and 13) by catalytic hydrogenation.
Cyclization of 3-(2-ethoxycarbonyl-7-chloroindol-4-yl)propionic acid (10) with polyphosphoric acid (PPA) took place at the 5-position of indole ring to give a tricyclic ketone (14).
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■ Photochemical Rearrangement of Fused Zwitterionic Pyridazines and Photochemical Ring Contraction of Fused Pyrimidone
Takao Yamazaki,* Masanori Nagata, Shun-ichi Hirokami, and Sumiko Miyakoshi
*Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama, Toyama 930-0194, Japan
Abstract
Photolysis of zwitterionic pyridazine (1a-c) in liquid phase afforded pyrimidin-4-ones (2a-c). Photolysis of 6,7,8,9-tetrahydro-2-methyl-4H-pyrido[1,2-a]pyrimidin-4-one (2a) in methanol gave l,6-diaza-3-methoxy-2-methyl-4-oxospiro[4,5]dec-2-ene (3a). Photolysis of (2a) in ethanol gave also 1,6-diaza-3-ethoxy-2-methyl-4-oxospiro[4,5]dec-2-ene (3a’). Hydrolysis of (3a) in methanol or in chloroform containing a small amount of water yielded 2-(α-acetyl-α-methoxyacetyl)-3,4,5,6-tetrahydropyridine (4a).
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■ Synthesis of 1,3-Bis(hydroxymethyl)-β-carboline Derivatives
Fumiko Hamaguchi* and Sadao Ohki
*Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
1,3-Bis(hydroxymethyl)-β-carboline derivatives were synthesized by Pictet-Spengler or Bischler-Napieralski reactions, followed by LAH reductions. Among them, 1,3-bis(hydroxymethyl)-2-benzyl-1,2,3,4-tetrahydro-β-carboline (2) hydrochloride was proved to be comparatively effective as an antiflammatory agent.
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■ Synthesis of 2,3-Bis(trifluromethyl) Indole by the Reaction of Aromatic Nitrones with Hexafluorobut-2-yne
Yoshiro Kobayashi,* Itsumaro Kumadaki, and Tsutomu Yoshida
*Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
Reaction of N-phenyl-α-arylnitrones with hexafluorobut-2-yne was examined. p-Anisyl-, phenyl-, and p-nitrophenyl-nitrones gave 2,3-bis(trifluoromethyl)indole through recyclization of the primary adducts to oxazoline compounds followed by hydrolysis and cyclization, while the isoxazoline compound underwent rearrangement to N,N-dimethyl-N’-phenyl-phenylenediamine compound, when the aryl was a p-dimethyl-aminophenyl group.
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■ The Synthesis of Cryptopleurospermine, a Benzilic Alkaloid of Cryptocarya pleurosperma
Gordon C. Dunmore,* Richard H. Manske, and Russell Rodrigo
*Guelph-Waterloo Centre for Graduate Work in Chemistry, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada
Abstract
Cryptopleurospermine 5 is synthesised from the aldehydes 13 and 15 through the intermediacy of the trimethylsilyl cyanohydrin of 13 used as a carbonyl anion equivalent.
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■ A Convenient Method for a Preparation of Oxiranes
Teruo Kutsuma,* Ichigaku Nagayama, Tokuji Okazaki, Tadakatsu Sakamoto, and Sanya Akaboshi
*Research Laboratories, Ohta Pharmaceutical Co., Ltd., Namiki, Kawaguchi, Saitama 332, Japan
Abstract
Oxiranes have been prepared in moderate to excellent yields via an one-pot process under a very mild condition. To an acetonitrile solution of dimethylsulfonium methylide prepared in situ by treating dimethyl sulfide with dimethyl sulfate, followed by sodium methoxide, was added carbonyl compounds at an ambient temperature to give oxiranes.
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■ Nitration of 1-Cyanoisoquinoline 2-Oxide and Isoquinoline 2-Oxide
Masatomo Hamana* and Hirohisa Saito
*Faculty of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
Abstract
The nitration of 1-cyanoisoquinoline 2-Oxide (1) with potassium nitrate and sulfuric acid gave 5- and 6-nitro derivatives (2 and 3). The reaction was affected by the concentration of sulfuric acid, and only 3 was obtained from the reaction in 85% acid at 70°, though in a small yield. The nitration with fuming nitric acid (d=1.50) led to the formation of 3 in fairly good yields together with small amounts of 8-nitro derivative (7).
Further, the nitration of isoquinoline 2-oxide (9) with fuming nitric acid was found to give 5-, 6- and 8-nitro derivatives (10, 11 and 12). The orienting effect of the N-oxide function is apparently operative in the formation of 11 and 12.
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■ Formtion of Some Heterocycles through Ring Transformation of 1-Arylazetidin-2-ones
Shinzo Kano,* Tsutomu Ebata, Yoko Denta, Satoshi Hibino, and Shiroshi Shibuya
*School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan
Abstract
Treatment of 4-hydroxymethyl-1-phenylazetidin-2-one (2) with methanesulfonic acid at room temperature yielded 4-anilino-2-oxotetrahydrofuran (3). On heating 4-benzylcarbamoyl-1-phenylazetidin-2-one (4) in methanesulfonic acid, anilinosuccinimide (6) was obtained. N-Methyl analogue (7) was also obtained from 4-methylcarbamoyl-1-phenylazetidin-2-one (5). 4-(2-Piperidino)-1-(4-methoxyphenyl)azetidin-2-one (9) gave octahydro-4-(4-methoxyphenyl)indolizin-2-one (10) under base-catalyzed conditions. Furthermore, 3-(4-methoxyanilinomethyl)-4-hydroxy-3,4-dihydrocarbostyril (14) was obtained by acid-catalyzed rearrangement of the corresponding 3-suhstituted 1-arylazetidin-2-one (13). 3-(4-Methoxyanilino)-4-hydroxyoctahydroindolizin-2-one (17) was also ohtained by the application of these nucleophilic cleavage of -N-CO- bond to the corresponding 1-arylazetidin-2-one (16).
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■ Rection of Ethyl 4-Bromocrotonate with Acetoacetamides
Tetsuzo Kato,* Takuo Chiba, Hiroko Sato, and Tetsuo Ito
*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan
Abstract
Ethyl 4-bromocrotonate (1) reacted with acetoacetamide (4) at room temperature to give ethyl 5-carbamoyl-6-oxo-2-heptenoate (10), which was transformed into ethyl 3-acetyl-2-oxopyrrolidine-5-acetate (6) and ethyl 4-carbamoyl-2,3-dihydro-5-methylfuran-2-acetate (8).
Similar reaction of compound 1 with N-methylacetoacetamide (5) afforded ethyl 3-acetylecgoninate (7). Reaction of compound 1 with ethyl acetoacetate (2) gave rise to ethyl 2,3-dihydro-4-ethoxycarbonyl-5-methylfuran-2-acetate (9).
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■ Photoarylation. I. Photochemical Synthesisn of Benzothieno[2,3-c][1,x]diazanaphthalene Systems by Intramolecular Dehydrochlorination
Masanao Terashima,* Koichi Seki, Kazuhiko Itoh, and Yuichi Kanaoka
*Faculty of Pharmaceutical Scicences, Higashinihonngakuen University, 1757 Kanazawa, Toubetu-cho, Ishikari-gun, Hokkaodo 061-0212, Japan
Abstract
By intramolecular photoarylation of the amides derived from 3- chlorobenzathiaphene-2-carboxylic acid and aminopyridines, novel polycyclic heteroaromatic systems were synthesized. This approach may be employed as a supplemental method for the oxidative photocyclization.
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■ Synthesis of 5-Alkyl- and 5-Acyl-uridines via 6-Mercaptouridine (Nucleosides and Nucleotides. XVII)
Hideo Inoue, Masako Takada, Masayo Takahashi, and Tohru Ueda*
*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
Several 5-alkyl- and 5-acyl-uridines have been prepared by the allylation or acylation of 2’,3’-O-isopropylidene-6-mercapto-uridine followed by the desulfurization.
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■ Synthesis of 5- and 6-Aminoimidazo[4,5-b]pyridine Ribonucleossides (A New Type of Adenosine Analogs) by Coupling Reactions
Tokuo Itoh,* Jun‘ichi Inaba, and Yoshihisa Mizuno
*Faculty of Pharmaceutical Sciences, Hokkaido University, Kita 12 Nishi 6, Kita-ku, Sapporo, Hokkaido 060-0812, Japan
Abstract
Synthesis of 5- (2) and 6-amino-3-(β-D-ribofuranosyl)-3H-imidazo[4,5-b]pyridine (3) is described. Ribosylation of 5-acetamidoimidazo[4,5-b]pyridine by “the mercuric cyanide-nitromethane” procedure gave rise to 3-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-3H-derivative 5 (71.2% yield) together with a considerable amount (18.3%) of 1-isomer (7). A trimethylsilylated derivative of 6-nitro- imidazo[4,5-b]pyridine (16) was also ribosylated in the presence of stannic chloride to yield 3-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)-3H-derivative (17) (35%) and its positional isomer (19) (10.8%).
The blocked nucleosides (5, 7, 17, and 19) were converted into the corresponding free nucleosides (2, 9, 3, and 21). Physical properties (pKa-values, chemical shifts, uv absorption maxima, and CD-parameters) of the newly prepared nucleosides are also reported.
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■ The Photo-sensitized Oxidation of Morusin
Taro Nomura* and Toshio Fukai
*School of Pharmaceutical Sciences, Toho University, 2-2-1, Miyama, Funabashi, Chiba 274-8510, Japan
Abstract
Photo-sensitized oxidation of morusin (I) in the presence of sensitizers (rose bengal, hematoporphyrin) afforded morusinhydroperoxide (II), compound A (III), and two other compounds (IV, V). IV and V were formed via “ene” reaction. Photo-sensitized oxidation of I was carried out in the presence of 2,4,6-tri-tert-butylphenol, a radical quencher, or of triethylene diamine (Dabco), a singlet oxygen quencher. In the former case, II1 and III were not obtained, but IV and XIII, whereas in the latter case, IV and V were not obtained, but II and III. On the basis of the above results, the possible mechanism of the formation of II from I was discussed.
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■ The Conformational Analysis of Saturated Heterocycles. Part LXXXIII. Conformational Properties of 2-Oxo-9,10-diazadecalin
Victor J. Baker, Alan K. Katritzky,* and Fernando M. S. Brito Palma
*School of Chemical Sciences, University of East Anglia, Norwich, Northfolk NR4 7TJ, U.K.
Abstract
Proton nmr spectroscopy shows that the newly synthesised bicycle I exists 70% in the trans conformation Ia and 30% in the cis conformation Ib.