Chemical and Pharmaceutical Bulletin
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ISSN-L : 0009-2363
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Volume 49, Issue 4
Displaying 1-32 of 32 articles from this issue
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Regular Articles
  • Structure-Activity Relationship (SAR) Studies on Oxazolidinone Antibacterial Agents. 1. Conversion of 5-Substituent on Oxazolidinone
    Ryukou TOKUYAMA, Yoshiei TAKAHASHI, Yayoi TOMITA, Tomio SUZUKI, Toshih ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 347-352
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.347
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    A structure-activity relationship (SAR) study on 5-substituted oxazolidinones as an antibacterial agent is described. The oxazolidinones, of which 5-acetylaminomethyl moiety was converted into other functions, were prepared and evaluated for antibacterial activity. Elongation of the methylene chain (8) and conversion of the acetamido moiety into guanidino moiety (12) decreased the antibacterial activity. The replacement of carbonyl oxygen (=O) by thiocarbonyl sulfur (=S) enhanced in vitro antibacterial activity. Especially, compound 16, which had the 5-thiourea group, showed 4-8 stronger in vitro activity than linezolid. Our SAR study revealed that the antibacterial activity was greatly affected by the conversion of 5-substituent.
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  • Structure-Activity Relationship (SAR) Studies on Oxazolidinone Antibacterial Agents. 2.1) Relationship between Lipophilicity and Antibacterial Activity in 5-Thiocarbonyl Oxazolidinones
    Ryukou TOKUYAMA, Yoshiei TAKAHASHI, Yayoi TOMITA, Masatoshi TSUBOUCHI, ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 353-360
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.353
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    5-Thiourea and 5-dithiocarbamate oxazolidinones were synthesized as a continuation of research on 5-thiocarbonyl oxazolidinone antibacterial agents considering the hydrophobic parameters of the molecule. The structure-activity relationship (SAR) study revealed that the antibacterial activity on 5-thiocarbonyl oxazolidinones was significantly affected by the lipophilicity, especially the calculated log P value and the balance between 5-hydrophilic (or hydrophobic) substituent and hydrophobic (or hydrophilic) substituents on the benzene ring. Some of 5-thiocarbonyl oxazolidinones were found to have good in vitro antibacterial activity against gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE).
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  • Structure-Activity Relationship (SAR) Studies on Oxazolidinone Antibacterial Agents. 3.1) Synthesis and Evaluation of 5-Thiocarbamate Oxazolidinones
    Ryukou TOKUYAMA, Yoshiei TAKAHASHI, Yayoi TOMITA, Masatoshi TSUBOUCHI, ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 361-367
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.361
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    A series of 5-thiocarbamate oxazolidinones was prepared and tested for in vitro and in vivo antibacterial activities. The results of in vitro antibacterial activity indicated that the 5-thiocarbamate group was a suitable substituent for the activity by the 5-moderate hydrophilicity. The compounds within a favorable log P value range were found to have potent in vitro antibacterial activity against gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE). Compounds 3a and 4h were superior to linezolid in both in vitro and in vivo potency and were considered to be hopeful compounds. We also discuss the pharmacokinetic properties of several compounds in mice.
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  • Photochemical and Oxidative Degradation of the Solid-State Tretinoin Tocoferil
    Reiko TERAOKA, Yasuyuki KONISHI, Yoshihisa MATSUDA
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 368-372
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.368
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    The photostability of tretinoin tocoferil was investigated under irradiation with three kinds of lamps, i.e., a cool white fluorescent lamp, a UV-A fluorescent lamp and a D65 fluorescent lamp. A combination of the cool white fluorescent lamp and the UV-A fluorescent lamp, and the D65 lamp having relative spectral power distribution similar to that of direct daylight, correspond to options 2 and 1 in ICH Guidelines, respectively. The photodegradation apparently followed second-order kinetics under these light sources and the degradation rate constant under exposure by the D65 lamp was larger than that by the cool white fluorescent lamp. The drug was susceptible to degradation by visible and UV light below 480 nm and was degraded most remarkably at around 420 nm, showing a wavelength-dependency. The semi-logarithmic plots of apparent degradation rate constant against the reciprocal of illuminance showed a good linear relationship in the Arrhenius-type fashion, and the photostability under ordinary illumination conditions could be predicted from the data obtained under the accelerated illumination conditions. The rate of oxidative degradation was slightly accelerated with the rise of temperature. Thermodynamic parameter was calculated from the Arrhenius plot. The degradation rate constant rapidly increased in proportion to partial pressure of oxygen below 20 kPa.
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  • Interaction of Microcrystalline Cellulose and Water in Granules Prepared by a High-Shear Mixer
    Tatsuya SUZUKI, Hiroshi KIKUCHI, Etsuo YONEMOCHI, Katsuhide TERADA, Ke ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 373-378
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.373
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    Microcrystalline cellulose (MCC) granules were prepared by wet granulation using a high-shear mixer. Physical characteristics of the granules were investigated using near IR spectrometry, thermogravimetry and isothermal water vapor adsorption. Near IR spectra of dried MCC granules prepared for various granulation times exhibited different peak intensities at 1428, 1772, and 1920 nm, which were assigned to functional groups of cellulose or water. On isothermogravimetric analysis, the rate of dehydration of water was shown to decrease with granulation time. These results suggest that the physical structure of MCC could change during the granulation process, and the interaction between MCC and water was gradually strengthened. The isothermal water vapor adsorption curves suggested that the amorphous region of MCC would be divided by the strong shear force of the impeller, because the high adsorption ability of intact MCC in the low humidity region was diminished in granules collected following 5 and 10 min of granulation. It was suggested that MCC formed a network which caught water within its structure during the wet granulation process.
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  • Synthesis and Anti-influenza Virus Activity of Tricyclic Compounds with a Unique Amine Moiety
    Mitsuru OKA, Yoshiro ISHIWATA, Noriyuki IWATA, Naoki HONDA, Takuji KAK ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 379-383
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.379
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    Several novel tricyclic compounds with a unique amine moiety (1, 2a-i) were designed and prepared based on the structure of triperiden for the development of anti-influenza virus agents. An in vitro antiviral assay showed that 1-(1-azabicyclo[3.3.0]octan-5-yl)-1-(4-fluorophenyl)-1-(2-tricyclo[3.3.1.13, 7]decyl)methan-1-ol hydrochloride (2f) has a potent anti-influenza A virus activity. Furthermore, since 2f was well tolerated in mice, 2f is promising as a novel anti-influenza virus agent for humans.
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  • Acid-Catalyzed Photoreaction of 6-Chloro-1, 3-Dimethyluracil and Mesitylene: Formation of Photocycloadducts and Their Characterization1)
    Kazue OHKURA, Ken-ichi NISHIJIMA, Koh-ichi SEKI
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 384-390
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.384
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    In contrast to the previously reported short time required (1 h) for photolysis of 6-chloro-1, 3-dimethyluracil (6-CIDMU) and mesitylene, in the presence of TFA, resulting in two major products: 1, 3, 6, 8, 10-pentamethyl-cyclooctapyrimidine derivative (1d), and diazapentacyclo[6.4.0.01, 3.02, 5.04, 8]dodecane (2c), prolonged irradiation (18 h) of this same mixture yields novel pentalenopyrimidine derivatives, including diazapentacyclo[6.4.0.01, 3.02, 6.04, 8]dodecane (3c).
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  • Synthesis of New Fused Pyrimidines by Isocyanate and Isothiocyanate
    A.Z.M. Shaifullah CHOWDHURY, Yasuyuki SHIBATA
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 391-395
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.391
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    o-Aminonitrile or o-aminoester compounds were cyclized to fused pyrimidines by reacting with ethyl iso(thio)cyanatoacetate in pyridine, and then were methylated, halogenated and subsequently displaced by the amines studied.
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  • Prolyl Endopeptidase Inhibitors from the Underground Part of Rhodiola sachalinensis
    Wenzhe FAN, Yasuhiro TEZUKA, Khin May NI, Shigetoshi KADOTA
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 396-401
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.396
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    The methanolic extract of the underground part of Rhodiola sachalinensis was found to show inhibitory activity on prolyl endopeptidase (PEP, EC. 3.4.21.26), an enzyme that plays a role in the metabolism of proline-containing neuropeptidase which is recognized to be involved in learning and memory. From the MeOH extract, five new monoterpenoids named sachalinols A (24), B (25) and C (26) and sachalinosides A (23) and B (27) were isolated, together with twenty-two known compounds, gallic acid (1), trans-p-hydroxycinnamic acid (2), p-tyrosol (3), salidroside (4), 6″-O-galloylsalidroside (5), benzyl β-D-glucopyranoside (6), 2-phenylethyl β-D-glucopyranoside (7), trans-cinnamyl β-D--glucopyranoside (8), rosarin (9), rhodiocyanoside A (10), lotaustralin (11), octyl β-D-glucopyranoside (12), 1, 2, 3, 6-tetra-O-galloyl-β-D-glucose (13), 1, 2, 3, 4, 6-penta-O-galloyl-β-D-glucose (14), kaempferol (15), kaempferol 3-O-β-D-xylofuranosyl(1→2)-β-D-glucopyranoside (16), kaempferol 3-O-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside (17), rhodionin (18), rhodiosin (19), (−)-epigallocatechin (20), 3-O-galloylepigallocatechin-(4→8)-epigallocatechin 3-O-gallate (21) and rosiridin (22). Among these, nineteen compounds other than 3, 4 and 9 have been isolated for the first time from R. sachalinensis, and six (6, 8, 13, 16, 17, 20) are isolated from Rhodiola plants for the first time. Among them, six compounds (13, 14, 18, 19, 21, 22) showed noncompetitive inhibition against Flavobacterium PEP, with an IC50 of 0.025, 0.17, 22, 41, 0.44 and 84 μM, respectively.
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  • Reaction Kinetics of Solid-state Cyclization of Enalapril Maleate Investigated by Isothermal FT-IR Microscopic System
    Shun-Li WANG, Shan-Yang LIN, Ting-Fang CHEN
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 402-406
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.402
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    To investigate the reaction kinetics of the solid-state degradation process of enalapril maleate, a Fourier transform infrared microspectroscope equipped with thermal analyzer (thermal FT-IR microscopic system) was used. The isothermal stability study was conducted at 120-130 °C for 1-2 h and changes in the three-dimensional plots of the IR spectra of enalapril maleate with respect to heating time were observed. The study indicates that the bands at 1649, 1728, and 1751 cm-1 assigned to intact enalapril maleate gradually reduced in peak intensity with heating time. However, the peak intensities at 1672 and 1738 cm-1 (due to enalapril diketopiperazine (DKP) formation) and at 3250 cm-1 (corresponding to water formation) gradually increased with heating time. The solid-state diketopiperazine formation and the degradation process of enalapril maleate via intramolecular cyclization were found to be simultaneous. The isothermal decomposition curves were sigmoidal and were characterized by induction and acceleration periods, indicating the presence of autocatalytic solid-state decompositions. Moreover, the power-law equation (n=1/4) was found to provide the best fit to the kinetics of decomposition. This isothermal FT-IR microscopic system was easily used to investigate the degradation of enalapril maleate and the concomitant formation of DKP. The solid-state reaction of enalapril maleate required an activation energy of 195±12 kJ/mol to undergo the processes of decomposition and intramolecular cyclization.
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  • Synthesis of Phenanthridones Using Diels—Alder Reactions of 4-Substituted 2(1H)-Quinolones Acting as Dienophiles
    Reiko FUJITA, Kazuhiro WATANABE, Toshiteru YOSHISUJI, Hisao MATSUZAKI, ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 407-412
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.407
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    Diels—Alder reactions of 2(1H)-quinolones having an electron-withdrawing group at the 4-position with 1, 3-butadiene derivatives were carried out to give the phenanthridones richly functionalized under the conditions of atmospheric and high pressure. Furthermore, the reactivities of 4-substituted 2(1H)-quinolones acting as a dienophile were examined using MO calculation.
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  • Viewing of Complex Molecules of Ethidium Bromide and Plasmid DNA in Solution by Atomic Force Microscopy
    Kuniharu UTSUNO, Masamichi TSUBOI, Shunji KATSUMATA, Toschitake IWAMOT ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 413-417
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.413
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    Tertiary structure changes in plasmid DNA, induced by ethidium bromide intercalation, have been observed in aqueous solutions by the use of an atomic force microscoe. A relaxed closed circular pBR322 molecule became a positively supercoiled complex on the drug binding. The supercoiling always resulted in an interwound (or a plectonemic) form, but never a solenoidal (or a toroidal) form. A quantitative analysis of the compactness of such supercoiled complexes has been carried out.
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  • The Molecular and Crystal Structure of tert-Butyl Nα-tert-Butoxycarbonyl-L-(S-trityl)cysteinate and the Conformation-Stabilizing Function of Weak Intermolecular Bonding
    Anna Eugenia KOZIOL, Beata SZADY, Elzbieta MASIUKIEWICZ, Barbara RZESZ ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 418-423
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.418
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    The title compound, C31H37NO4S {systematic name: (R)-tert-butyl-2-[(tert-butoxycarbonyl)amino]-3-(trityl-sulfanyl)propanoate} is an L-cysteine derivative with three functions: NH2, COOH and SH, blocked by protecting groups tert-butoxycarbonyl, tert-butyl and trityl, respectively. The main chain of the molecule adopts the extended, nearly all-trans C5 conformation with the intramolecular N-H…O=C hydrogen bond. The urethane group is not involved in any intermolecular hydrogen bonding. Only weak intermolecular hydrogen bonds and hydrophobic contacts are observed in the crystal structure. These are C-H…O hydrogen bonds and CH/π interactions with donor…acceptor distances, C…O ca. 3.5 Å and C…C ca. 3.7 Å, respectively. The first type of interaction links phenyl H-atoms and carbonyl groups. The second type of interaction is formed between a methyl group of the tert-butyl fragment and a trityl phenyl ring. The resulting molecular conformation in the crystal is very close to an ab initio minimum energy conformer of the isolated molecule. The extended C5 conformation of the main peptide chain is the same and there is slight discrepancy in the disposition of trityl phenyl rings. Their small dislocation creates the possibility of forming the entire network above of extensive, specific, weak intermolecular interactions; these constrain the molecule and permit it to retain the minimum energy C5 conformation of its main chain in the solid state. In contrast, in n-hexane solution, where such specific interactions cannot occur, only a small population of the molecules adopts the extended C5 conformation.
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  • Synthesis and Gastrointestinal Prokinetic Activity of Novel Benzamide Derivatives with Amphoteric Side Chains
    Jun SAKAGUCHI, Nobuhiko IWASAKI, Yuji IWANAGA, Takaharu SAITO, Eiji TA ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 424-436
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.424
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    Novel benzamide derivatives (19-24, 32a-c, 43d-f), each possessing a cycloaminoalkanecarboxylic acid side chain, were synthesized and their gastrointestinal prokinetic and dopamine D2 receptor antagonist activities were evaluated. 4-[(4-Amino-5-chloro-2-methoxybenzoyl)amino]-1-piperidineacetic acid (19) exhibited the most potent gastro- and colon-prokinetic activities, through intravenous administration to conscious dogs, and also showed the reduced dopamine D2 receptor antagonistic activity. However, 19 showed only weak gastrointestinal prokinetic activity after oral administration. Several ester prodrugs (44-62) of 19 were tested for pharmacological activities as well as physicochemical and metabolic stability; the butyl ester (46) was consequently selected as a promising gastrointestinal prokinetic agent with reduced side effects.
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  • Studies on the Constituents of Cimicifuga Species. XXVIII.1) Four New Cycloart-7-enol Glycosides from the Underground Parts of Cimicifuga simplex WORMSK
    Akiko KUSANO, Makio SHIBANO, Daisuke TSUKAMOTO, Genjiro KUSANO
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 437-441
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.437
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    Four new cycloart-7-ene triterpenol arabinosides, bugbanosides C-F, were isolated from the underground parts of Cimicifuga simplex WORMSK. (Ranunculaceae). The structures were elucidated as 12β-acetoxy-3β, 15α, -24R, 25-tetrahydroxy-16, 23-dione-cycloart-7-ene 3-O-α-L-arabinopyranoside, 12β-acetoxy-24R, 25-epoxy-3β, 15α-dihydroxy-16, 23-dione-cycloart-7-ene 3-O-α-L-arabinopyranoside, 12β-acetoxy-24R, 25-epoxy-3β-hydroxy-16, 23-dione-cycloart-7-ene 3-O-α-L-arabinopyranoside, and 16, 23R: 16, 24S-diepoxy-3β, 12β, 15α, 25-tetrahydroxy-cycloart-7-ene 3-O-α-L-arabinopyranoside on the basis of spectral and chemical evidence. The circular dichroism (CD) of bugbanosides C-F showed strong negative maxima at 214-217 nm due to a cycloart-7-ene system, as well as other cycloart-7-ene triterpenes. The CD data showed to be useful in determining basic skeletons, including absolute stereostructures of cycloart-7-ene triterpenes.
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  • Six New Dammarane-type Triterpene Saponins from the Leaves of Panax ginseng
    De-Qiang DOU, Ying-Jie CHEN, Li-Hong LIANG, Fa-Gen PANG, Noriko SHIMIZ ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 442-446
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.442
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    Six new minor saponins, together with known ginsenosides, were isolated from the leaves of Panax ginseng. The new saponins were named as ginsenoside-Rh5, -Rh6, -Rh7-Rh8, -Rh9 and -Rg7, and their structures were elucidated on the basis of chemical and physicochemical evidence to be as follows: ginsenoside-Rh5: 3β, 6α, 12β, 24ζ-tetrahydroxy-dammar-20 (22), 25-diene 6-O-β-D-glucopyranoside (1), -Rh6: 3β, 6α, 12β, 20 (S)-tetrahydroxy-25-hydroperoxy-dammar-23-ene 20-O-β-D-glucopyranoside (2), -Rh7: 3β, 7β, 12β, 20 (S)-tetrahydroxy-dammar-5, 24-diene 20-O-β-D-glucopyranoside (3), -Rh8: 3β, 6α, 20 (S)-trihydroxy-dammar-24-ene-12-one 20-O-β-D-glucopyranoside (4), -Rh9: 3β, 6α, 20 (S)-trihydroxy-12β, 23-epoxy-dammar-24-ene 20-O-β-D-glucopyranoside (5) and -Rg7: 3-O-β-D-glucopyranosyl 3β, 12β, 20 (S), 24 (R)-tetrahydroxy-dammar-25-ene 20-O-β-D-glucopyranoside (6).
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  • Constituents of Holothuroidea. 10.1) Isolation and Structure of a Biologically Active Ganglioside Molecular Species from the Sea Cucumber Holothuria leucospilota
    Koji YAMADA, Rei MATSUBARA, Masafumi KANEKO, Tomofumi MIYAMOTO, Ryuich ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 447-452
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.447
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    Three ganglioside molecular species, HLG-1 (1), HLG-2 (2), and HLG-3 (3) have been obtained from the lipid fraction of the chloroform/methanol extract of the sea cucumber Holothuria leucospilota. The structures of these gangliosides have been determined, on the basis of chemical and spectroscopic evidence, as 1-O-[(N-glycolyl-α-D-neuraminosyl)-(2→6)-β-D-glucopyranosyl]-ceramide (1), 1-O-[(N-glycolyl-α-D-neuraminosyl)-(2→4)-(N-acetyl-α-D-neuraminosyl)-(2→6)-β-D-glucopyranosyl]-ceramide (2) and 1-O-[α-L-fucopyranosyl-(1→11)-(N-glycolyl-α-D-neuraminosyl)-(2→4)-(N-acetyl-α-D-neuraminosyl)-(2→6)-β-D-glucopyranosyl]-ceramide (3). The ceramide moieties were composed of heterogeneous phytosphingosine, sphingosine and 2-hydroxy fatty acid units. Compounds 2 and 3 represent new ganglioside molecular species. These three ganglioside molecular species showed neuritogenic activity toward the rat pheochromocytoma cell line, PC-12 cell, in the presence of NGF (nerve growth factor).
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  • Sweet Pregnane Glycosides from Telosma procumbens
    Vo Duy HUAN, Kazuhiro OHTANI, Ryoji KASAI, Kazuo YAMASAKI, Nguyen Viet ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 453-460
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.453
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    An intensely sweet polyoxypregnane glycoside, telosmoside A15 (15), was isolated from an Asian Asclepiadaceae plant, Telosma procumbens, collected in Vietnam. This is the first time a sweet pregnane glycoside has been found, and its sweetness intensity is 1000 times greater than that of sucrose. From the same plant, 17 other new glycosides were isolated, having the same aglycone; they are named telosmosides A1-A14 (1-14) and A16-A18 (16-18). Some of these glycosides are also sweet, but others are tasteless or bitter. Chemical structures of the 18 glycosides were determined, and the structure-taste relationship was discussed.
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  • Convenient Synthesis of 4-Trifluoromethyl-Substituted Imidazole Derivatives
    Masami KAWASE, Setsuo SAITO, Teruo KURIHARA
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 461-464
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.461
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    Mesoionic 4-trifluoroacetyl-1, 3-oxazolium-5-olates (1), obtained from the reaction of N-acyl-N-alkylglycines (2) with trifluoroacetic anhydride, react with ammonia to give 4-trifluoromethyl-3, 4-dihydroimidazoles (3) in high yields. Dehydration of 3 gives 4-trifluoromethylimidazoles (4) in high yields. The novel ring transformation of 1 into 3 occurs via a regioselective attack of ammonia on the C-2 position of the ring.
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  • Analysis of the Marker Compounds of Rhodiola rosea L. (Golden Root) by Reversed Phase High Performance Liquid Chromatography
    Markus GANZERA, Yurdanur YAYLA, Ikhlas A. KHAN
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 465-467
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.465
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    An HPLC method permitting the first simultaneous detection of 5 marker compounds (salidroside, rosarin, rosavin, rosin, rosiridin) of R. rosea was developed. A separation was achieved within 27 min by using C-18 column material, a phosphate buffer/acetonitrile gradient system and at a separation temperature of 60 °C. All five compounds could be detected at concentrations as low as 0.62 μg/ml and were clearly assignable in R. rosea plant material and commercial products. Therefore, this quantitative and qualitative applicability of the method offers efficient and reliable means for the evaluation of R. rosea and products thereof.
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  • Stereoselective Reactions. XXXIV.1) Enantioselective Deprotonation of Prochiral 4-Substituted Cyclohexanones Using Chiral Bidentate Lithium Amides Having a Bulky Group Instead of a Phenyl Group on the Chiral Carbon
    Masaharu TORIYAMA, Keizo SUGASAWA, Shigeyasu MOTOHASHI, Norio TOKUTAKE ...
    Article type: scientific monograph
    2001 Volume 49 Issue 4 Pages 468-472
    Published: 2001
    Released on J-STAGE: April 26, 2002
    DOIhttps://doi.org/10.1248/cpb.49.468
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    Using chiral bidentate lithium amides having a bulky group instead of a phenyl group on the chiral carbon, enantioselective deprotonation of prochiral 4-substituted cyclohexanones in the presence of excess trimethylsilyl chloride was examined in THF in the absence and in the presence of HMPA. It is shown that enantioselectivity of the reactions decreases as the substituent on the chiral carbon of the chiral lithium amides and the substituent at the 4-position of cyclohexanones become reasonably bulky. An eight-membered cyclic transition state model is proposed for this deprotonation reaction.
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Notes
Communications to the Editor
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