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
Shigeru Oae's Special Issues, Vol. 44, No. 1, 1997
Published online:
■ Synthesis of Various Substituted Benzo[c]-2,7-naphthyridines and an Approach towards the Skeleton of Meridine. Considerations about the Effect of Copper(II) Oxide
Patrick Björk, Johan Malm, Anna-Britta Hörnfeldt, and Salo Gronowitz*
*Organic Chemistry 1 Chemical Center, University of Lund, P. O. Box 124, S-22100, Lund, Sweden
Abstract
Derivatives of benzo[c]-2,7-naphthyridines have been prepared in good yields and in one step through the use of the Pd(0)-catalyzed cross couplings of formly- and 4- acetyl-3-pyridyltrimethylstannanes with ortho-bromoacetanilides. Perlolidine, an alkaloids present in perennial rye grass, was readily prepared in a few steps taking advantage of the cross coupling. An approach towards the pentacyclic ring skeleton of meridine has also been made, leading to several new derivatives of benzo[c]-2,7-naphthyridine. All cross couplings are greatly promoted by the addition of stoichiometric amounts of copper(II) oxide and a comparison with the use of other catalytic systems in the Pd(0)-catalyzed cross couplings is made.
Published online:
■ Formation of Cyclic Oligosulfides by Reaction of Hydrazones with Disulfur Dichloride
Yi-Nan Jin, Akihiko Ishii, Yoshiaki Sugihara, and Juzo Nakayama*
*Department of Chemistry, Faculty of Science, Saitama University, Saitama, Saitama 338-8570, Japan
Abstract
Reactions of some hydrazones with disulfur dichloride were reinvestigated in the absence of a base with expectation of obtaining dithiirane or thiosulfine derivatives. However, treatment of hydrazones derived from 1-adamantyl phenyl ketone, pivalophenone, and benzophenone with disulfur dichloride gave pentathianes and hexathiepanes along with other products, while di-t-butyl ketone hydrazone gave a novel heterocyclic compound, 1,1-di-t-butyltetrathiolane, though in a low yield.
Published online:
■ Preparation, Properties, and Oxidation of Novel Bis(1,3-dithiole) Compounds Containing A Di(2-thienyl)methane Unit
Akira Ohta and Yoshiro Yamashita*
*Department of Structural Molecular Science, The Graduate University for Advanced Studies, Institute for Molecular Science, Myodaiji, Okazaki 444-8585, Japan
Abstract
Novel bis(1,3-dithiole) compounds (5) and (6) containing a di(2-thienyl)methane unit have been prepared by either a Wittig or a Wittig-Horner reaction. These compounds showed irreversible cyclic voltammetric behavior. Oxidation products of 5 and 6 were strongly dependent on the substituents (R1) on the C6-carbon atoms of the 1,4-dithiafulvenyl groups. In the case of R1 = H (5), intermolecular coupling giving a redox-active oligomer selectively occurred. On the other hand, when R1 was methyl, 6 underwent deprotonation by oxidation to give the corresponding stable dithienylmethyl cations showing intense absorptions in the near-infrared region ( > 900 nm in MeCN).
Published online:
■ Synthesis and Cytotoxicity of 5-Carbo Analogues of Acetomycin
Jun'ichi Uenishi, Naoko Kobayashi, Osamu Yonemitsu,* Takuma Sasaki, and Yuji Yamada
*Department of Chemistry, Faculty of Science, Okayama University of Science, 1-1 Ridai-cho, Okayama 700-0005, Japan
Abstract
Six carbo analogues of anti-cancer antibiotic, acetomycin (1) are synthesized. (±)-(3S*,4S*,5R*)-Dihydro-3-acetyl-5-iodomethyl-3,4-dimethyl-2(3H-furanone (3α), (±)-(3S*,4S*,5S*)-dihydro-3-acetyl-3,4,5-trimethyl-2(3H)-furanone (4α), (±)-(3S*,4S*,5R*)-dihydro-3-acetyt-3,4-dimethyl-5-(phenylthio)methyl-2(3H-furanone (5α), and their diastereoisomers at C-5, 3β, 4β, and 5β are derived from the same intermediate, (±)-(2S*,3R*)-2-(4-methoxybenzyl)oxymethyl-2,3-dimethyl-4-pentenoic acid (7) in 5 and 6 steps, respectively. The carbo analogues exhibit perfect resistance in hydrolysis against pig liver esterase. Among them, β-isomers at C-5 indicate more potent inhibition than α-isomers against three tumor cell lines.
Published online:
■ Diastereoselective 1,3-Dipolar Cycloaddition of 2-(α,β-Unsaturated) Acyl-3-phenyl-l-menthopyrazoles
Choji Kashima*, Katsumi Takahashi, Iwao Fukuchi, and Kiyoshi Fukusaka
*Department of Chemistry, University of Tsukuba, 1-1-1 Ten-nodai, Tsukuba-shi, Ibaraki, 305-8571, Japan
Abstract
The 1,3-dipolar cycloadducts of N-(α,β-unsaturated) acylpyrazoles (2) with benzonitrile oxide or nitrones were afforded in good yield. In the cases of nitrones, the addition of MgBr2 or ZnBr2 promoted the stereoselectivity as well as the acceleration of the reaction rate. In the reaction of 2f and 2g, the big jump on the diastereoselectivity was accomplished by the addition of MgBr2, and (3’S,4’R,5’S)-8 was obtained as optically pure form in over 90% yield. These isoxazolidinecarbonylpyrazoles were converted into azetidinones in moderate yield with the retention of their stereo structures.
Published online:
■ Synthesis of Taxoids I. Regioselective Lewis Acid-mediated Ring-opening of Aryl Orthoacetates
Naoyuki Harada, Tomiki Hashiyama,* Kunihiko Ozaki, Tetsuo Yamaguchi, Akira Ando, and Kenji Tsujihara
*Lead Optimization Research Laboratory, Tanabe Seiyaku Co.Ltd., 2-2-50, Kawagishi, Toddda, Saitama 335-8505, Japan
Abstract
The reaction of aryl orthoacetates with acetyl bromide readily proceeded regioselectively to afford the desirable aryl bromides in the presence of tin(II) or zinc bromide as a catalyst. The synthesis of some docetaxel derivaives is also described by using this improved process.
Published online:
■ Synthesis of Optically Pure β-Phenylselenoalanine Through Serine-β-lactone: A Useful Precursor of Dehydroalanine
Mitsuru Sakai, Kimiko Hashimoto, and Haruhisa Shirahama*
*School of Science, Kwansei Gakuin University, 1-1-155 Uegahara, Nishinomiya 662-8501, Japan
Abstract
Optically pure L- and D-β-phenylselenoalanines (PhSeAla), useful precursors of dehydroalanine, were synthesized from L- and D-serine-β-lactone. Elimination reactions of the phenylseleno group to form the dehydroalanine were examined.
Published online:
■ Optically Pure Alkoxychlorosulfuranes. Synthesis and Transformation to Chiral Sulfoxides, N-p-Tosylsulfilimines, and Sulfonium Ylides
Jian Zhang, Tamiko Takahashi, and Toru Koizumi*
*Faculty of Pharmaceutical Sciences, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama, Toyama 930-0194, Japan
Abstract
Optically pure alkoxychlorosulfuranes (1) have been prepared by using the 2-exo-hydroxy-10-bornyl group as a chiral ligand. The structure of sulfurane (1a) was confirmed by 1H-nmr, 13C-nmr, and mass spectra Nucleophilic reaction of 1 with water and NaNHTs proceeded with retention of configuration to give optically pure sulfoxides (2) and N-p-tosylsulfilimines (3), respectively. Sulfonium ylides (4) were obtained as mixtures of diastereomers by the reaction of 1 with NaCH(CO2Me)2. The absolute configuration of sulfilimime (3c) was determined by X-ray analysis.
Published online:
■ Photoinduced Molecular Transformations. Part 160. Furan Annelation of 2-Hydroxynaphthoquinone Involving Photochemical Addition and Radical Fragmentation: Exclusion of the Intermediacy of [2+2] Cycloadduct in a One-Pot Formation of Furanoquinones by the Regioselective 3+2 Photoaddition of Hydroxyquinones with Alkenes
Hisanori Senboku, Yoshinori Kajizuka, Kazuhiro Kobayashi, Masao Tokuda, and Hiroshi Suginome*
*Organic Synthesis Division, Faculty of Engineering, Hokkaido University, Sapporo 060, Japan
Abstract
2-Acetoxy-1,4-naphthoquinone underwent [2+2] photoaddition to 2-methylpropene, giving a cyclobutanol acetate exclusively. Hydrolysis of the acetate with acid gave the corresponding cyclobutanol, which was stable under the conditions of an alkene-quinone photoaddition; hydrolysis with a base gave a fused 1-indanone derivative. Photolysis of the hypoiodite generated from the cyclobutanol derivative with mercury(II) oxide-iodine in benzene induced a β-scission of the cyclobutanoxyl radical to give a 2,3-dihydronaphtho[2,3-b]furan-4,9-dione and its [1,2-b]furan-4,5-dione isomer.
Published online:
■ A Facile and Convenient Synthetic Method for Fluorine-containing 1,2-Dihydropyrimidines and Pyrimidines
Etsuji Okada*, Tatsuhiko Kinomura, Hiroshi Takeuchi, and Masaru Hojo
*Department of Chemical Science andd Engineerring, Faculty of Engineering, Kobe University, Rokkodai-cho, Nada-ku, Kobe 657-8501, Japan
Abstract
β,β-Bis(trifluoroacetyl)vinylamine (1) reacted easily with various aliphatic and aromatic aldehydes in the presence of aqueous ammonia under mild conditions to give 5-trifluoroacetyl-4-trifluoromethyl-1,2-dihydropyrimidines (2) in good yields. Dehydrogenation of 2 with DDQ afforded the corresponding pyrimidines (3) in excellent yelds.
Published online:
■ Structural Analysis of N-(ω-Phenylalkyl)substituted Quinoxalin-2(1H)-ones and -Thiones
Akira Katoh*, Tohru Yoshida, Junko Ohkanda, and Takehiko Nishio
*Department of Industrial Chemistry, Faculty of Engineering, Seikei University, Musashino-shi, Tokyo 180-8633, Japan
Abstract
Reaction of quinoxalin-2(1H)-one (1) with v-phenylalkyl halides in the presence of bases gave a mixture of N- and O-alkylated products, which were separated by column chromatography. N-Alkylquinoxalin-2(1H)-ones (2a-c) were easily converted into the corresponding thiones (4a-c) by treatment with Lawesson’s reagent. From X-ray crystallographic analysis, it was revealed that the molecular arrangement of N-phenethylquinoxalin-2(1H)-one (2a) was quite different from that of the corresponding thione (4a). Compound (4a) existed in a pair of conformational isomers in the crystalline state, and this was also supported by the solid-state 13c nmr spectral data.
Published online:
■ cis-Fused Dihydrofurano-1,2,4-trioxanes
Charles W. Jefford,* Shu-juan Jin, Jean-Claude Rossier, Shigeo Kohmoto, and Gérald Bernardinelli
*Department of Organic Chemistry, Laboratory fo Crystallography, University of Geneva, 30, quai Ernest Ansermet, 1211 Geneva 4, Switzerland
Abstract
The endoperoxide obtained from 2,5-diphenylfuran at -30°C on catalysis with trimethylsilyl trifluoromethanesulfonate condenses with pivalaldehyde, acetone and cyclohexanone to give the corresponding cis-fused dihydrofurano-1,2,4-trioxanes (20,21,22 and 23) respectively in yields not greater than 27%. The reaction of pivalaldehyde with the endoperoxide derived from 1,4-diphenyl-1,3-cyclopentadiene gives the cis and trans-3-tert-butyl substituted cis-fused cyclopenteno-1,2,4-trioxanes (26 and 27) in 75% yield. The structures of 22, 23, 26 and 27 are determined by X-ray.
Published online:
■ Ethyl α-Amino-β,β-Diethoxypropionate, a Useful Synthon for the Preparation of 3,4-Fused Pyridine-6-carboxylates from Aromatic Aldehydes
Sunil K. Singh, Mouloud Dekhane, Mireille Le Hyaric, Pierre Potier, and Robert H. Dodd*
*Institut de Chimie des Substances Naturelles, Centre National de la Recherche Scientifique, Avenue de la Terrasse, Bat. 27, 91198 Gif-sur-Yvette Cedex, France
Abstract
An efficient synthesis of ethyl α-amino-β,β-diethoxypropionate (1), via a titanium tetrachloride-catalyzed coupling reaction of ethyl nitroacetate and triethyl orthoformate, is described. Condensation of 1 with various aldehydes followed by reduction and titanium tetrachloridepromoted cyclization of the products afforded 3,4-fused pyridine-6-carboxylates belonging to the azaindole, γ-carboline and isoquinoline families of heterocycles.
Published online:
■ A Silver Salt – Iodine Reagent System for the Deprotection of Monothioacetals and Dithioacetals
Kiyoharu Nishide, Daisaku Nakamura, Kouichi Yokota, Toshio Sumiya, Manabu Node,* Masaru Ueda, and Kaoru Fuji
*Kyoto Pharmaceutical University, Misasagi, Yamashina, Kyoto 607-8414, Japan
Abstract
A new reagent (silver salt - iodine) system was developed for the deprotection of monothioacetals and dithioacetals. The reactions using this reagent system afforded the parent carbonyl compounds in rnoderale to quantitative yields under mild conditions. These deprotections were also effective in the catalytic amount of this reagent. As an application of this deprotective reagent system, synthesizing optically active α-hydroxyaldehyde using chiial 1,3-oxathiane was demonstrated.
Published online:
■ Environmentally Benign Chemistry: Microwave-induced Stereocontrolled Synthesis of β-Lactam Synthons
Bimal K. Banik, Maghar S. Manhas, Ernest W. Robb, and Ajay K. Bose*
*McLean Chemical Sciences Center, Stevens Institute of Technology, Castle Point on the Hudson, Hoboken, NJ 07030, U.S.A.
Abstract
Microwave irradiation in open glass vessels in unmodified commercial microwave ovens has permitted stereoconholled synthesis of useful β-lactam synfhons not withstanding the fact that the nature of specific activation (if any) of organic reactions by microwaves is not yet completely understood.
Published online:
■ Synthesis and Reactivities of 1,3-Dimethyl-2-(α-hydroxybenzyl)imidazolium and 1,3-Dimethyl-2-(α-hydroxybenzyl)benzimidazolium Iodides
Akira Miyashita,* Akihito Kurachi, Yoshiyuki Matsuoka, Noriko Tanabe, Yumiko Suzuki, Ken-ichi Iwamoto, and Takeo Higashino
*Schol of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
Abstract
1,3-DimethyI-2-(α-hydroxybenzyl)benzimidazolium iodide (3a) was synthesized from 1-methylbenzimidazole (10) through two steps involving lithiation and quaternization. Treatment of 3a with 4-chloro-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine (6) afforded 4-benzoyl-1-phenyl-1H-pyrazolo[3,4-d]pyrimidine (15a). 4-Benzoylquinazoline (14a) and 7-benzoyl-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine (16a) were given by reaction of 3a with 4-chloroquinazoline (5) and 7-chloro-3-phenyl-3H-1,2,3-triazolo[4,5-d]pyrimidine (7). Treatment of 3a with benzaldehyde (9a) gave benzoin (8a). Similar results were obtained in the reactions of 1,3-dimethyl-2-(α-hydroxybenzyl)imidazolium iodide (4a).
Published online:
■ Thiovalidamine Derivatives of manno-and gluco-Type: Remote Activation and Anchimeric Assistance
Yoshisuke Tsuda, * Tomoko Nakamoto, Fumiyuki Kiuchi, and Yukihiko Kameda
*Faculty of Pharmaceutical Scicences, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan
Abstract
The oxazolidone (3) derived from validamine (1) was dithiocarbonylated, on treatment with NaH followed by CS2-Mel, to the N,O-dicarbodithioate (6). On treatment with NaH-Mel, this afforded the manno-type thiovalidamine derivative (7) and then the gluco-type thiovalidamine derivative (8) following the pathway shown in Scheme 2: an activation at a C=S group by methylation, transferring this activation to a remote position accompanied with decarboxylation, and cyclization of the neighboring group to the transferred position (C-3).
Published online:
■ Synthesis of New Chiral Catalysts, Isoquinuclidinylmethanols, for the Enantioselective Addition of Diethylzinc to Aryl Aldehydes
Hiroto Nakano, Kazuto Iwasa, and Hiroshi Hongo*
*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
Abstract
New chiral ligands, isoquinuclidinylmethanols, were prepared and their catalytic abilities of asymmetric induction were examined in the addition of diethylzinc to aldehydes to furnish secondq alcohols in up to 76% e.e.
Published online:
■ Novel Synthesis of Heterocycles Using Nickel(0)-catalyzed [2+2+2] Cocyclization: Catalytic Asymmetric Synthesis of Isoindoline and Isoquinoline Derivatives
Yoshihiro Sato, Toyoki Nishimata, and Miwako Mori*
*Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
Abstract
A nickel(0)-catalyzed asymmetric [2+2+2] cocyclization has been realized for the first time. That involves conceptually new enantiotopic group selective formation of the nickelacyclopentadiene (18) and produces the isoindoline (26a) (73% ee, 78% conv. yield) and isoquinoliie (27b) (54% ee, 62% yield) having benzylic chiral carbon centers.
Published online:
■ Convenient One-Pot Synthesis of Sodium Salt of 5-Mercapto-1,2,3-thiadiazole
Katsumasa Harada,* Teruhiko Inoue, and Hiroshi Yoshida
*Ube Research Laboratory, UBE Indusries, Ltd., 1978-5 Kogushi, Ube Yamaguchi 755, Japan
Abstract
Trichloroacetoaldehyde-p-toluenesulfonyIhydrazone (3) derived from chloral hydrate reacted in situ with polysulfide salt in the range of pH 10~11 to afford the corresponding 5-mercapto-1,2,3-thiadiazole salt(2) in high yield (69.5 %).
Published online:
■ Acid-catalyzed Photoreaction of 6-Chloro-1,3-dimethyluracil to p- and m-Xylene: Formation of Novel Photocycloadducts, 6-Methylene-9,11,X-trimethyl-9,11-diazapentacyclo[6.4.0.01,3.02,5.04,8]dodecane-10,12-diones and 5-Methylene-9,11,X-trimethyl-9,11-diazapentacyclo[6.4.0.01,3.02,6.04,8]dodecane-10,12-diones
Kazue Ohkura, Koh-ichi Seki,* Hajime Hiramatsu, Keiichi Aoe, and Masanao Terashima
*Faculty of Pharmaceutical Sciences, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan
Abstract
Uv irradiation of 6-chloro-1,3-dimethyluracil in p- and m-xylenes i n the presence of trifluoroacetic acid gave novel photocycloadducts, 6-methylene-9,11,x-trimethyl-9,11-diazapentacyclo[6.4.0.01,3.02,5.04,8]dodecane-10,12-diones and 5-methylene-9,11,x-trimethyl-9,11-diazapentacyclo[6.4.0.01,3.02,6.04,8]dodecane-10,12-diones, together with tetramethylcyclooctapyrimidine-2,4-diones as the sole regioisomer. The modes of the cycloaddition were discussed.
Published online:
■ Facile Synthesis of (+)- and (-)-Geissman-Waiss Lactones
Takafumi Kouyama, Hirofumi Matsunaga, Tadao Ishizuka, and Takehisa Kunieda*
*Faculty of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan
Abstract
(+)- and (-)- Geissman-Waiss lactones (1), were prepared from the readily accessible (4R, 5R)- and (4S, 5S)-5-allyl-4-methoxy-2-oxazolidinones [(+)- and (-)-7], respectively, in a highly stereocontrolled manner from the previously reported building block, 3-[(1S)-2-exo-alkoxy-1-apocamphanecarbonyl]-2-oxazolones (4).
Published online:
■ Tandem Peterson-Michael Reaction Using α-Silylalkylphosphine Chalcogenides and Horner-Emmons Reaction of in situ Generated α-Carbanions of Its Products
Takayuki Kawashima,* Mio Nakamura, and Naoki Inamoto
*Department of Chemistry, Graduate School of Science, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8567, Japan
Abstract
Title tandem reaction was achieved by using α-(trimethylsilyl)alkylphosphine chalcogenides and the lithio derivative of 2-hydroxytetrahydropyran. The Homer-Emmons reaction of the tandem products was accomplished to give the corresponding 2-(β-styryl)tetrahydropyran derivatives by in situ generation and trapping of α-lithio derivatives, followed by Warren‘s method of olefination.
Published online:
■ Synthesis of Thiophene Derivatives Bearing a Silicon Atom
Osamu Hoshino* and Tetsuya Hirayama
*Faculty of Pharmaceutical Sciences, Science University of Tokyo, 12, Ichigaya Funagawara-machi, Shinjuku-ku, Tokyo 162-0826, Japan
Abstract
Synthesis of thiophene derivatives containing a sillcon atom is described. Silylation of 2-thienylmethyl chloride (12) with trichlorovinylsilane or chloro(chloromethyl)dimethylsilane was accomplished by addition of 12 to a mixture of Mg and the former reagent in THF or by addition of a mixture of 12 and the latter reagent to a mixture of Mg in THF to give dichloro(2-thienylmethyl) vinylsilane (13) or chloromethyl(dimethyl)(2-thienylmethyl)siane (18). The Grignard reagent (19) of 18 reacted with carbon dioxide, dimethyl carbonate or benzaldehyde to produce dimethyl(2-thienylmethyl)silylacetic acid (20), methyl dimethyl(2-thienylmethyl)silylacetate (21) or 2’-[dimethyl(2-thienylmethyl)silyl]-1’-phenylethanol (22).
Published online:
■ A New Efficient Synthesis of Nicotianamine and 2'-Deoxymugineic Acid
Takayuki Shioiri,* Naoko Irako, Sachiko Sakakibara, Fumiyoshi Matsuura, and Yasumasa Hamada
*Faculty of Pharmaceutical Sciences, Nagoya City University, Tanabe-dori, Mizuho-ku, Nagoya 467-8603, Japan
Abstract
Nicotianamine and 2’-deoxymugineic acid, phytosiderophores, have been efficiently synthesized, which will be suitable for large scale production of these plant physiologically important compounds. The synthetic method for 2,3”-dideoxy-3”-oxomugineic acid was also investigated.
Published online:
■ Synthesis of Benzo[a]quinolizines by the Intramolecular Double Michael Reaction under Three Different Conditions
Masataka Ihara, Masami Yamada, Yohei Ishida, Yuji Tokunaga, and Keiichiro Fukumoto*
*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan
Abstract
Benzo[a]quinolizines (4A-C) and (5A-C) were synthesized by the intramolecular double Michael reaction of amide esters (3A-C). canied out using three reagent systems; TBDMSOTf-Et3N, TMSI-(TMS)2NH, and Bu2BOTf-(TMS)2NH.
Published online:
■ Syntheses of 1-Substituted (SS)-3-p-Tolylsulfinyl-1,4-dihydropyridines, Chiral NADH Model Compounds
Satoshi Obika, Toshihiko Nishiyama, Satoshi Tatematsu, Masahiro Nishimoto, Kazuyuki Miyashita, and Takeshi Imanishi*
*Faculty of Pharmaceutical Science, Osaka University, 1-6 Yamadaoka, Toyonaka, Osaka 560-0043, Japan
Abstract
(SS)-3-(p-Tolylsulfinyl)-1,4-dihydropyridines with various kinds of substituents on the N-1 position were synthesized from (SS)-1-lithio-3-(p-tolylsulfinyl)-1,4-dihydropyridine, which was generated on reaction of the 1-benzoyl derivative with methyllithium.
Published online:
■ Amphidinolides: Unique Macrolides from Marine Dinoflagellates
Masami Ishibashi and Jun'ichi Kobayashi *
*Faculty of Pharmaceutical Sciences, Hokkaido University, Sapporo 060-0812, Japan
Abstract
A series of macrolides, named amphidinolides, have been isolated from the laboratory-cultured marine dinoflagellates Amphidinium sp., which were symbionts of the Okinawan marine flatworm Amphiscolops sp. These macrolides possess unique chemical structures as well as cytotoxic activities. Here we describe our recent results on the isolation, structure elucidation, and biosynthesis of these unique macrolides.
Published online:
■ The 7-N-Oxides of Purines Related to Nucleic Acids: Their Chemistry, Synthesis, and Biological Evaluation
Tozo Fujii *, Taisuke Itaya, and Kazuo Ogawa
*Faculty of Pharmaceutical Scicences, Kanazawa University, 13-1 Takara-machi, Kanazawa 920-0934, Japan
Abstract
Recent advances in the chemistry, synthesis, and biological evaluation of the 7-N-oxides of purines related to nucleic acids are reviewed. The 7-N-oxides covered are those of guanine (1), adenine (2). and hypoxanthine (3) and of related compounds such as 6-mercaptopurine (6-MP) (72). the 6-thioxo analogue of 3, and 6-methylthiopurine, a simple model for azathioprine (78), which were all unknown until recently.