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
Edward C. Taylor's Special Issues, Vol. 35, No. 2, 1993
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■ An Enantiocontrolled Formal Total Synthesis of (+)-Ipomeamarone, (-)-Ngaione, and Their Epimers
Hideo Nemoto, Tetsuro Tanabe, Masatoshi Nagamochi, and Keiichiro Fukumoto*
*Pharmaceutical Institute, Tohoku University, Aobayama, Sendai 980-8578, Japan
Abstract
A concise enantiocontrolled synthesis of (+)-(5S,2R)- and (+)-(5R,2R)-5-(3-furyl)-2-iodomethyl-2-methyloxolanes, (6) and (5), was achieved starting from (+)-(R )-2-hydroxymethyl-2-methylcyclobutanone (11) which was efficiently prepared by the tandem asymmetric epoxidation and 1,2-rearrangement or 2-cyclopropylidenepropanol (9). This constitutes an enantiocontrolled formal total synthesis of (+)-ipomeamarone (1), (+)-epiipomeamarone (2), (-)-ngaione (3) and its epimer (4).
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■ Isolation and Structure of Axinastatin 4 from the Western Indian Ocean Marine sponge Axinella cf. carteri
George R. Pettit, Feng Gao, and Ronald Cerny*
*Center Research Institute, Department of Chemisty, Arizona State University, Main Campus, P.O. Box 872404, Tempe, AZ 85287-2404, U.S.A.
Abstract
The Republic of The Comoros marine sponge Axinella cf. carteri has been found to contain a cell growth inhibitory (P388 lymphocytic leukemia cell line ED50 0.057 μg/ml, and comparable activity against a series of human cancer cell lines) cyclo-heptapeptide named axinastatin 4 (3). The new peptide was obtained in 1.0 x 10-6% yield (6.1 mg) from 600 kg (wet wt) of the sponge. The structure of axinastatin 4 was deduced as cyclo-(Pro-Leu-Thr-Pro-Leu-Trp-Val) by a combination of high field (400 and 500 Mhz) 2D nmr (1H-1H, 1H-13C, HMBC and NOE) and high resolution mass spectral (principally by ms/ms) measurements and subsequent interpretations.
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■ Enantioselective Synthesis of the α-Hydroxy-α-methyl-β-hydroxy Units via Asymmetric Aldol Reaction
Teruaki Mukaiyama,* Isamu Shiina, Jun Izumu, and Shu Kobayashi
*Department of Applied Chemistry, Faculty of Science, Science University of Tokyo, Kagurazaka 1-3, Shinjuku-ku, Tokyo 162-8601, Japan
Abstract
The α-hydroxy-α-methyl-β-hydroxy units are enantioselectively prepared by way of asymmetric aldol reactions between both achiral β,β-disubstituted silyl enolates and aldehydes. (-)-2-C-Methyl-D-threono-1,4-lactone is conveniently synthesized by using this reaction.
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■ On the Decomposition of 1,2,4-Trioxan-5-ones
Charles W. Jefford* and M. Graça H. Vicente
*Department of Organic Chemistry, University of Geneva, 30, quai Ernest Ansermet, 1211 Geneva 4, Switzerland
Abstract
The thermal and chemical properties of six 3,6-substituted 1,2,4-trioxan-5-ones were studied by flash-vacuum thermolysis (FVT) and by treatment with electron-transfer agents. The 1,2,4-trioxan-5-ones exhibited unusual stability both chemically and thermally, but eventually underwent decomposition with loss of carbon dioxide yielding the carbonyl components.
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■ Anomalous Cyclization in an Attempted Synthesis of the '7-Thiomorphinan', System
Parthasarathi Rajagopalan* and Joseph C. Calabrese
*CNS Diseases Research, The Du Pont Merck Pharamceutical Co., Inc., Wilmington, DE 19880 - 0353, U.S.A.
Abstract
The acid catalyzed cyclization of 8-benzyl-3,4,5,6,7,8-hexahydro-1H-thiopyrano[3,4-c]pyridine hydrochloride (10) did not furnish the expected the ‘7-thiomorphinan’ (11) but 4-(2-mercaptoethyl)-1,2,3,5,10,10a-hexahydrobenzo[g]quinoline (12) instead. The synthesis of 10 and the mechanism of formation of 12 are described.
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■ The Synthesis of Heterocyclic C-Terminal Units Which Mimic the Transition State in the Cleavage of the Leu-Val Bond of Angiotensinogen by Renin
J. Donald Albright, Charles F. Howell,* and F. W. Sum
*American Cyanamid Company, Medical Research Division, Lederle Laboratories, Pearl River, NY 10965, U.S.A.
Abstract
The stereospecific synthesis of (S)2-amino-3-cyclohexyl-(R)1-(2-furanyl)-propan-1-ol (17) and (S) 2-amino-3-cyclohexyl-(R)1-(2-thienyl)-propan-1-ol (18) from t-Boc-L-phenylalanine is described. Reduction of the furan ring of (4S-trans)-4-(cyclohexylmethyl)-5-(2-furanyl)-2-oxazolidinone (15) gave two tetrahydrofuranyl diastereomers (21) and (22). Each tetrahydrofuranyl oxazolidinone (21 and 22) was converted stereospecifically in high yield to the (S, R, R) and the (S, R, S) tetrahydrothienyl oxazolidinones (29) and (27), respectively.
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■ Synthesis and Evaluation of 8,10-Dideazatetrahydrofolic Acid and Derivatives
Joseph I. DeGraw,* William T. Colwell, Roy L. Kisliuk, Yvette Gaumont, and Francis M. Sirotnak
*Bio-organic Chemistry Laboratory, SRI International, Menlo Park, California 94025, U.S.A.
Abstract
Syntheses of 8,10-dideazatetrahydrofolic acid and its 5-N-methyl and 5-N-formyl derivatives are reported. Hydrolysis of 2,4-diamino-4-deoxy-8,10-dideazapteroic acid in hot alkali afforded 8,10-dideazapteroic acid. Coupling with diethyl L-glutamate followed by saponification gave 8,10-dideazafolic acid. Hydrogenation in acidic media gave the tetrahydro compound, while hydrogenation in the presence of formaldehyde yielded the 5-N-CH3 analog. The 5-N-CH3 compound was more potent than 5,10-DDTHF as an inhibitor of growth for L1210 cells in culture. In contrast to 5,10-DDTHF, the locus of action was apparently unrelated to inhibition of GAR formyltransferase. Unfortunately, 5-CH3-8,10-DDTHF was not active in vivo against an L1210 challenge in mice.
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■ Steric and Electronic Effects Controlling the Synthesis of Bridgehead Nitrogen Heterocycles
George deStevens,* Matthew Eager, and Christine Tarby
*Department of Chemistry and The Charles A. Dana Research Institute, Drew University, Madison, New Jersey 07940, U.S.A.
Abstract
The synthesis of imidazo[2,1-b][-1,3,4-]thiadiazoles via the condensation of an α-haloketone with 2-amino-1,3,4-thiadiazoles is controlled by the nature of the substituent at the 5-position of the thiadiazole.
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■ Design of Antineoplastic Agents on the Basis of the "2-Phenylnaphthalene-Type" Structural Pattern. I. Synthesis of Substituted 3-Phenylquinazolones, Benzoxazolo[2,3-b]quinazolones and Benzothiazolo[2,3-b]quinazolones
Chia-Chung Cheng,* Dun-Fu Liu, and Ting Chao Chou
*Drug Development Laboratory, The University of Kansas Cancer Center and Department of Pharmacology, Toxicology & Therapeutics, The University of Kansas Medical Center, Kansas City, Kansas 66160-7419, U.S.A.
Abstract
A number of substituted 3-phenylquinazolin-4-ones, 12H-benzoxazolo[2,3-b]quinazolin-12-ones and 12H-benzothiazolo[2,3-b]quinazolin-12-ones designed and synthesized on the basis of a “2-phenylnaphthalene-type” structural pattern hypothesis. The postulated pattern, which was uncovered among a substantial number of compounds of both natural and synthetic origins, was noted to be associated with compounds possessing a variety of biological properties which include the antineoplastic activity. Several compounds designed for the present study were found to exhibit potent cytotoxicity against the growth of human promyelocytic leukemia (HL-60) cells.
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■ Dipolar Cycloaddition Route to the Synthesis of 1α,25-Dihydroxy-26-norvitamin D2 Derivatives
Peter M. Wovkulich,* Enrico G. Baggiolini, Bernard M. Hennessy, and Milan R. Uskokovic
*Roche Research Center, Hoffmann-La roche, Inc., 340 Kingsland Street, Nutley, New Jersey 07110, U.S.A.
Abstract
The intramolecular dipolar cycloadditions of nitrones derived from aldehydes (8) and (14) were found to proceed with a high degree of diastereoselectivity. By taking advantage of the functionality and stereochemical features residing in the cycloadducts (10) and (11), respectively, the two novel vitamin D2 derivatives (1c) and (1d) were synthesized.
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■ Syntheses of 3-Substituted 6-Amino-2-methylpyrimido[4,5-e][1,2,4]triazin-8-ones (7-Substituted 6-Methyl-6-azapterins) as Inhibitors of Dihydropteridine Reductase from Human Brain
David Randles, Hiroyasu Taguchi, and Wilfred L. F. Armarego*
*Division of Biochemistry and Molecular Biology, John Curtin School of Medical Research, Australian National University, GPOBox 334, Canberra, ACT 2601, Australia
Abstract
Condensation of 5,5-dibromo-2-aminopyrimidine-4,6-dione with S-methyl-, S-benzyl- and S-p-carboxybenzyl-2-methylisothiosemicarbazide hydrobromides provided 3-methylthin-, 3-benzylthio- and 3-p-carboxybenzylthio-6-amino-2-methylpyrimido[4,5-e][1,2,4]triazin-8-ones. Similar condensations with 1-amino-1-methylguanidinium bromide and 2,3-dimethylamidrazone hydrochloride gave 3-amino- and 3-methyl-6-amino-2-methylpyrimido[4,5-e][1,2,4]triazin-8-one. The 3-thio derivatives hydrolyse in aqueous solution to the same 2-methylpyrimido[4,5-e][1,2,4]triazine-3,8-dione. The ionization and 13C nmr spectra are consistent with the stated structures. These triazinones are not substrates for dihydropteridine reductase from human brain but are inhibitors of the reductase and their Ki values are reported.
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■ Formation of [7](2,6)Pyridinophanes by Ring Enlargement of a Pyrido[1,2-a]azepinone
Wolfman Maier, Manfred Keller, and Wolfgang Eberbach*
*Institute of Organic Chemistry and Biochemistry, University of Freiburg, Albertstrasse 21, D-7800 Freiburg, Germany
Abstract
Pyrido[1,2-a]azepinone (4) is deprotonated from the pyridine unit by lithium diisopropylamide affording lithium salt (7), which is trapped by electrophiles like D2O, benzoyl chloride and aldehydes. In the latter case subsequent intramolecular attack of the intermediate alkoxide to the lactam moiety leads to [7][2,6]pyridinophanes (9a,b). On reaction of 4 with the lithium-free phosphazene base tBu-P5 deprotonation takes place at the α-carbonyl position of the azepinone ring affording the enolate (6).
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■ The Synthesis of N-{2-Amino-4-substituted [(Pyrrolo[2,3-d]pyrimidin-5-yl)ethyl]benzoyl}-L-glutamic Acids as Antineoplastic Agents
Chuan Shih* and L. S. Gossett
*Cancer Research Division, Lilly Reserach Laboratories, Eli Lilly & Company, Lilly Corporate Center, Indianapaolis, IN 46285, U.S.A.
Abstract
A series of N-{2-amino-4-substituted[(pyrrolo[2,3-d]pyrimidin-5-yl)ethyl]benzoyl}-L-glutamic acids were synthesized. In this current synthesis, compound 2-amino-4-chloro-pyrrolo[2,3-d]pyrimidine (4) was selected as an important precursor for the preparation of key intermediates such as 5b, 10b, 15a and 15b. These highly functionalized pyrrolo[2,3-d]pyrimidines were then later coupled with either 4-ethynylbenzoylglutamate or 4-iodobenzoylglutamate in a palladium catalyzed Heck reaction and thus provided the basic skeleton of the targeted molecules. The availability of the chlorine atom at the 4-position of the pyrrolopyrimidine nucleus has allowed us to introduce different substituents at this position efficiently. By this approach, we were able to prepare avariety of 4-substituted pyrrolo[2,3-d]pyrimidine based folate antagonists (2a-2g) which are closely related to the novel thymidylate synthase inhibitor LY231514. In vitro analysis has demonstrated that some of these agents are highly cytotoxic against human leukemic cells (CCRF-CEM) in culture.
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■ α-Amino Ketones from Amino Acids as Precursors for the Knorr Pyrrole Synthesis
James M. Hamby* and John C. Hodges
*Parke-Davis Pharmaceutical research, Warner-Lambert Company, 2800 Plymouth Road, Ann Arbor, MI 48015-2430, U.S.A.
Abstract
A useful and versatile modification of the Knorr pyrrole synthesis is described. Key α-amino ketone intermediates for the Knorr condensation were readily prepared from the N-methoxy-N-methylamides of amino acids and condensed with 1,3-dicarbonyl compounds to afford tetrasubstituted pyrroles in good yields.
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■ Triazolopyrideines. 15. Reactions between Triazolo-pyridinium Ylides and Alkenes
Belen Abarca, Rafael Ballesteros,* and Gurnos Jones
*Departamento de Química Orgánica, Facultad de Farmacia, Universidad de Valencia, Calle Dr. Moliner, 50, E-46100 Burjassot (Valencia), Spain
Abstract
The triazolopyridine ylides (1) react with acrylates (2) to give 3-(2-pyridyl)acrylates (4a) and (4b), the 2-pyridylcyclobutanes (5a)-(5g), the pyridylpent-1-ene (8) and the zwitterion (3). The mechanism of reaction between the ylides (1) and acrylates or alkynes is discussed.
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■ High-Pressure Cycloaddition Reactions between Methyl 2H-Cyclohepta[b]furan-2-one-3-carboxylate and Ethoxyethene. Pressure Effect on the [8+2] and [4+2] Cycloadditions
Akira Mori, Yasuhiro Nukii, Hitoshi Takeshita,* and Tetsuo Nozoe
*Instituete of Advanced Material Study, Kyushu University, 6-1, Kasuga-koen, Kasuga 816-8580, Japan
Abstract
The high-pressure cycloaddition reaction between methyl 2H-cyclohepta[b]furan-2-one-3-carboxylate and ethoxyethene gave the [4+2] adducts as kinetically-controlled products. Heating the [4+2] adduct under 10,000 bar in the presence of the deuterated methyl 2H-cyclohepta[b]furan-2-one-3-carboxylate caused the retro-Diels-Alder reaction. However, formation of no azulene derivative was observed and no deuterium atom was incorporated into the recovered adduct.
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■ Synthesis and Characterization of New Types of 4-[2-(2-Hydroxyaryl)ethenyl]pyridinium Betaine Dyes
Akira Mori,* Shuji Kanemasa,* Etsuo Fujimoto, Eiji Wada, Hitoshi Takeshita, Nobuo Kato, and Akira Mori
*Instituete of Advanced Material Study, Kyushu University, 6-1, Kasuga-koen, Kasuga 816-8580, Japan
Abstract
Two types of pyridinium betaine dyes, 4-[4-(2-arylethenyl)-1-pyridinio]phenolates and 2-[2-(1-aryl-4-pyridinio)ethenyl]phenolates which have a chromophore either of ET-30 type or the stilbazolium betaine type, have been synthesized. Both types of dyes show negative solvatochromism in various solvents, the intensity of chromism depending upon the polarity of the solvent. Betaines (11a-c) have the possibility of two betaine structures, the ET-30 or the stilbazolium betaine types. The transition energies of 11a-c as well as 11g-i are linear with the same slope against the ET (30) scale of solvent polarity. Therefore, the stilbazolium betaine structure of 11a-c contributes to the negative solvatochromism. The dyes prepared could be an indicator of solvent polarity.
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■ Enzymatic Synthesis of Optically Active α-Hydroxybenzylpyridines
Mitsuhiro Takeshita,* Sachiko Yoshida, Takumi Sato, and Nami Akutsu
*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
Abstract
Synthesis of optically active α-hydroxybenzylpyridines by asymmetric reduction of benzoylpyridines and benzoylpyridine N-oxides with baker’s yeast, and enantioselective esterification of racemic α-hydroxybenzylpyridines by use of lipase PS have been described.
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■ New Dimeric Products from the Thermal and Photochemical Decomposition of 2-Azidophenazine
Angelo Albini, Gianfranco Bettinetti,* and Giovanna Minoli
*Department o f Organic Chemistry, University of Pavia, Via Taramelli 10, 27100 Pavia, Italy
Abstract
Re-examination of the thermal and photochemical decomposition of 2-azidophenazine reveals new pathways. Thus, besides reduction to the amine, the triplet nitrene yields the azo derivative and phenazino[1’,2’:5,6]pyridazino[4,3-a]phenazine while the singlet nitrene rearranges to the dehydroazepine and adds a further molecule of azide to yield an open-chain imine. The factors leading to the predominance of “dimeric” products from this type of heterocyclic azides are discussed.
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■ Nmr Studies and Structural Assignment of Paederoside
Shigenori Suzuki,* Kanehiko Hisamichi, and Katsuya Endo
*Tohoku Pharmaceutical University, 4-4-1 Komatsushima, Aoba-ku, Sendai 981-8558, Japan
Abstract
Detailed and extensive nmr analyses of paederoside have been carried out resulting to allow complete assignment of all of the 1H and 13C signals. The results provided unambiguous bases to support methyl thiocarbonate structure (3) for paederoside, a novel natural sulfur-containing iridoid glucoside of Paederia scandens.
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■ Simple Heterocycle, 2-Oxazolone, as Versatile Building Block for 2-Amino Alcohols. Chiral Synthesis of Polyhalothreonines
Tadao Ishizuka, Mitsuyasu Osaki, Hideharu Ishihara, and Takehisa Kunieda*
*Faculty of Pharmaceutical Sciences, Kumamoto University, 5-1 Oe-hon-machi, Kumamoto 862-0973, Japan
Abstract
Smooth radical-initiated addition of CCl4 and CCl3Br to 3-[(1S)-ketopinyl]-2-oxazolone gives a 1 : 1 mixture of readily separable (4S,5R)- and (4R,5S)-4-halogeno-5-trichloromethyl-2-oxazolinone derivatives, which serve for facile preparation of polychlorothreonines including 4,4-dichloro-2-amino-3-hydroxybutyric acid, known as antimicrobial armentomycin analog.
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■ Synthesis of 3-Trifluoromethylpyrazoles and 3-Trifluoromethylpyridazines from 2-Amino-1,1,1-trifluoro-3-phenylsulfonyl-2-propanol
Masahiko Takahashi,* Hiroyuki Kotasnima, and Toshimitsu Saitoh
*Department of Materials Sciences, Faculty of Engineering, Ibaraki University, 4-12-1 Nakanarusawamachi, Hitachi, Ibaraki 316-8511, Japan
Abstract
3-Trifluoromethylpyrazoles and 3-trifluoromethylpyridazines were prepared from 2-amino-1,1,1-trifluoro-3-phenylsulfonyl-2-propanol. In some cases elimination or substitution of the phenylsulfonyl group was observed.
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■ Pyrazolopyridines. 1. Formylation and Acylation of Pyrazolo[1,5-a]pyridines
Ken-ichi Tanji,* Takehiko Sasahara, Junko Suzuki, and Takeo Higashino
*Schol of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Shizuoka 422-8526, Japan
Abstract
In the treatment of pyrazolo[1,5-a]pyridines with dimethylformamide and, phosphorus oxychloride, Vilsmeier-Haack formylation proceeded at the 3-position, giving 3-pyrazolo[1,5-a]pyridinecarboxaldehydes. Reaction of the pyrazolo[1,5-a]pyridine with acyl halide gave 3-acylpyrazolo[1,5-a]pyridines. Conversion of the formyl group into the alkenyl group was achieved easily by Wittig reaction.
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■ Synthesis of LY288601, a 5.6-Dihydropyprrolo[2,3-d]pyrimidine Based Antifolate Compunds Related to LY231514
Charles J. Barnett* and Thomas M. Wilson
*Chemical Process Research and Development Division, Lilly Corporate Center, Lilly Reserach Laboratories, Eli Lilly & Company, Indianapaolis, IN 46285-4813, U.S.A.
Abstract
An expeditious synthesis of LY288601 (2), the 5,6-dihydro analog of the pyrrolo[2,3-d]pyrimidine-based antifolate compound LY231514 (1a), is described. The synthesis proceeds in eight steps from tert-butyl 4-iodobenzoate and involves the elaboration of a 2-amino-4-hyhxypyrimidine ring onto an activated 3-carboalkoxy-2-pyrrolidinone via reaction with guanidine as a key step.
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■ Photoreactions of 4- and 3-Azidocoumarins in the Presence of Nucleophiles
Keiichi Ito,* Yukako Higuchi, Chika Tame, and Junko Hariya
*Hokkaido Institute Pharmaceutical Sciences, 7-1 Katsuraoka-cho, Otaru 047-02, Japan
Abstract
The photoreactions of 4-azidocoumarins (1) and 3-azidocoumarin (2) in the presence of nucleophiles such as alcohols, thiol or amines generally gave 4-substituted 3-amino- and/or 3-substituted 4-aminocoumarins, while pyrone ring fission with incorporation of two moles of nucleophile was observed in the reaction of 1 in the presence of primary or secondary aliphatic amine as a nucleophile. Plausible mechanisms for these reactions are suggested.
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■ A Convenient Synthesis of 3-(Aryl)substituted 2,4(1H,3H)-Pteridinediones and Their Absorption and Fluorescence Spectorscopic Characteristics
Akira Katoh,* Junko Ohkanda, Hiroshi Sato, Tsuyoshi Sakamoto, and Keiryo Mitsuhashi
*Department of Industrial Chemistry, Faculty of Engineering, Seikei University, Musashino-shi, Tokyo 180-8633, Japan
Abstract
3-(Aryl)substituted 2,4(1H,3H)-pteridinediones are synthesized in high yields by addition and simultaneous cyclization of methyl 3-amino-2-pyrazinecarboxylate with isocyanates. The remarkable difference in the reactivity is observed among heterocumulenes. The absorption and fluorescence spectroscopic characteristics of the titled compounds are also discussed.
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■ 4-Ethoxymethylene-2-phenyl-5(4H)-oxazolone as a Synthon for the Synthesis of Some Fused Pyrimidines
Vladimir Kepe, Marijan Kocevar,* and Slovenko Polanc
*Department of Chemistry and Chemical Technology, University of Ljubljana, Askerceva 5, 61000 Ljubljana, Slovenia
Abstract
Treatment of 4-ethoxymethylene-2-phenyl-5(4H)-oxazolone with nitrogen-containing heterocycles, having amino group in ortho position to the ring nitrogen, leads to the corresponding 4-(arylaminomethylene)-2-phenyl-5(4H)-oxazolones, which can be further converted into different fused pyrimidinones. The (Z)-structure of the oxazolone exocyclic double bond has been determined on the basis of 13C nmr spectroscopy.
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■ The Rotational Isomers of Peracetylated C-Glycosylflavones
Takeshi Kato and Yutaka Morita*
*Faculty of Pharmaceutical Sciences, Josai University, 1-1 Keyakidai, Sakado, Saitama 350-0295, Japan
Abstract
In 1H- and 13C-nmr of peracetylated 8-C- and 6-C-glycosylflavones, the signal doublings were observed due to the restricted rotation of the acetylated glucosyl moiety. The conformations of rotational isomers of hepta-O-acetylvitexin and octa-O-acetylorientin were decided as +sp (major) and -sc (minor) for both compounds by nmr (CDCl3) spectral data. The characteristic chemical shift phenomena in nmr of glycosylflavonoid could be applicable to differentiate 8-C-glucoside from 6-C-glucoside.
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■ Synthesis and Characterization of Pyrroplinonecarboxylates Formed by Reaction of Vicinal Tricarbonyl Derivatives with Aldehyde Schiff Bases
Harry H. Wasserman,* David S. Ennis, Chi B. Vu, Gayle Schulte, Morton E. Munk, Mark Madison, and Kolandai V. Velusamy
*Department of Chemistry, Yale University, P.O. Box 6666, New Haven Connecticut 06511, U.S.A.
Abstract
A series of vicinal tricarbonyl derivatives undergo reaction with aldehyde Schiff bases forming pyrrolinone derivatives by benzilic acid-related rearrangements. The structures were established by X-ray analyses and, independently by the SESAMI NMR-based computer program.
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■ An Improved Synthesis of 4-[3-(Trifluoromethyl)-3H-diazirin-3-yl]benzoic Acid for Photoaffinity Labeling
Yasumaru Hatanaka,* Hitoshi Nakayama, and Yuichi Kanaoka
*Research Institute for Wakan-Yaku, Toyama Medical and Pharmaceutical University, 2630 Sugitani, Toyama, Toyama 930-0194, Japan
Abstract
An improved synthesis of 4-[3-(trifluoromethyl)-3H-diazirin-3-yl]benzoic acid, a key carbene precursor for photoaffinity labeling, was described. A new diazirine with amino group as a connective part was designed.