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Volume 65, Issue 6
Displaying 1-10 of 10 articles from this issue
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Keiji Nakano, Masato Kitamura2007 Volume 65 Issue 6 Pages 552-562
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSStructural investigation of organic compounds gives not only fundamental knowledge in chemistry but also guideline for design of functional materials and its synthetic strategies. The structure of aldols was systematically investigated. Intrinsic conformational preference was elucidated by DFT calculation of the simplest aldol, 3-hydroxypropanal. The “eclipsed” conformation with intramolecular hydrogen bond is the most stable. Cyclohexanone-derived aldols, which can fix at “eclipsed” conformation, were selected as standard compounds for systematic analysis of solutionphase behavior and crystal structure. The combination of molecular-weight measurement, NMR and IR studies in solution elucidated the detailed geometry of these typical aldols. The equilibrium distribution between conformers is controlled by the intramolecular and intermolecular hydrogen bond, gauche interactions between the vicinal substituents, and sometimes CH/π attraction. Since the conformational preference is not always fitted with the assumption in the empirical method for determining the relative configuration (Stiles-House method), this method must be used with the greatest care. The preferred structure in solution often differs greatly from the crystalline-state geometry. Generally the racemic C (3) -unsubstituted cyclohexanone-based aldols crystallize as a monomer or a heterochiral dimer with the stable “eclipsed” conformation. The enantiomerically pure aldols, however, tend to form intermolecular hydrogen bonds generating a helical chain. Introduction of a C (3) substituent completely destroys the stable conformation yielding an unusual C (2) -C (3) trans-diaxial conformation. This enables the formation of a hydrogen-bonded polymer along screw axis or glide plane.View full abstractDownload PDF (1792K) -
Takahiro Itoh, Toshiaki Mase2007 Volume 65 Issue 6 Pages 563-574
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSObesity poses a major risk for metabolic diseases like diabetes, hyperlipemia, cardiovascular disease and so on. Endogenous neuropeptide Y (NPY) is mediated by NPY receptors to cause the function which is involved in regulating feeding behavior. Recently, our basic research efforts identified highly potent and orally active NPY receptor antagonists. In this review article, we describe practical syntheses of three drug candidates from process chemistry perspective.View full abstractDownload PDF (2010K) -
Understanding for the Adaptation of Archaea to Harsh Environment and Toward a New Design for Lipid MoleculesNoriaki Yamauchi2007 Volume 65 Issue 6 Pages 575-584
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSArchaea live under harsh conditions such as low pH, high temperature, high salt conditions. The characteristic ether-lipid contributes to the tolerance of harsh living conditions. The biosynthetic studies of this characteristic lipid molecule provide a new insight for the adaptations of archaea for the extreme environment, and provide a design of new lipid molecules useful for drug delivery systems. At first, the biosynthetic studies of the isoprenoidal portion of halophilic archaea were performed. It reveals the isoprenoidal portion of halophlies is made from acetate and C-4 unit derived from amino acid such as lysine. Next, the biosynthetic study of calditol, the hydrophilic portion of Sulfolobus lipid-core that consists of 5-memberd carbocycle bound to glycerol with ether-linkage, was presented. The carbocycle of calditol is biosynthesized from glucose with C-C bond formation of C 1 and C 5. It may involve the “cyclase” enzyme of the calditol carbocycles with broad substrate specificity that can be seen at the central metabolism of then mophilic archaea.View full abstractDownload PDF (1571K) -
Yoshiyasu Fukuyama, Tomoyuki Esumi2007 Volume 65 Issue 6 Pages 585-597
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSPlants producing natural products remain one of the few sources of drug discovery, yielding unorthodox and often unexpected chemical structures. Since some classes of plant-derived natural products are frequently concentrated on the same genus, the extensive chemosystematic studies of the specific plants serve as a chemical library to discover candidates for drugs or biological probes for physiological studies. Vibsane-type diterpenes belong to rarely occurring natural products since they have been elaborated solely in Viburnum species such as V. awabuki, V odoratissimum, and V. suspensum. These diterpenes are further classified into 11-membered ring, 7-membered ring and rearranged (neovibsanin) types, thus putting their chemical diversity into a unique chemical library. We describe a variety of vibsanes, chemical correlations between three subtypes, and synthetic studies of vibsanin F, the simplest 11-membered ring vibsane, as well as neurotrophic activities of neovibsanins A-B.View full abstractDownload PDF (2077K) -
Yuichi Kobayashi, Tsuyoshi Itoyama2007 Volume 65 Issue 6 Pages 598-607
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSThis review summarizes the synthesis of cinchona alkaloids, especially quinine. First, the synthetic efforts done by Rabe, Prelog, and Woodward are briefly mentioned. Described next are the achievements of Uskokovic in 1970 s, who found useful stereoselective transformations, introduced key intermediates, and established transformation of homomeroquinene to quinine, though as a mixture with quinidine. Then, the first completely stereoselective synthesis of quinine published by Stork in 2001 is presented, in which the key step is a stereoselective reduction of the substituted tetrahydropyridine (imine) to the piperidine by using NaBH4. Finally, syntheses of quinine and quinidine published by Jacobsen and by us are presented, both of which feature the stereoselective formation of the epoxide moiety on one of the side chains attached to the piperidine and subsequent intramolecular epoxide ring opening with the piperidine nitrogen, while the construction of the piperidine ring and the stereoselectivities accompanied with are different each other.View full abstractDownload PDF (1260K) -
Masahiro Okada, Youji Sakagami2007 Volume 65 Issue 6 Pages 608-617
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSThe ComX pheromone is an extracellular signaling molecule that stimulates natural genetic competence controlled by quorum sensing in Bacillus subtilis. It has been suggested that ComX pheromone is posttranslationally modified oligopeptide with an isoprenoid at its tryptophan residue, but the precise structure was not known. Recently we determined the structure of the ComXRO-E-2 pheromone, from strain RO-E-2, showing that addition of a geranyl group to a tryptophan residue results in the formation of a tricyclic structure.
Here we report the structural determination of the ComXRO-E-2 pheromone with a focus on synthetic studies as follows : syntheses of six putative ComXRO-E-2 pheromones containing 1-, 2-, 4-, 5-, 6-, or 7-geranyl substituted tryptophan residues based on the HRMS analysis of the natural pheromone, and syntheses of ComXRO-E-2 pheromone and three diastereomers containing all possible geranyl modified tryptophan residues to confirm the precise stereochemistry based on the NMR analyses of the natural pheromone.View full abstractDownload PDF (1541K) -
Shingo Ito2007 Volume 65 Issue 6 Pages 618-619
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSThis mini review describes recent advances in transition metal-catalyzed carbon-carbon bond-forming reactions that allow direct use of simple aliphatic alcohols without derivatization or pre-activation. The sp3 carbon-oxygen bonds of alcohols can be transformed to carbon-carbon bonds through one-pot multiple reactions containing redox processes.View full abstractDownload PDF (362K) -
Tatsuya Mori, Noritada Matsuo2007 Volume 65 Issue 6 Pages 620-625
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSIt is well recognized that the ratio of fluorine-containing pesticides is increasing along with the progress of fluorine chemistry. In recent years, one third of new pesticides are containing fluorine atom (s). In many cases, they have remarkable pesticidal activity as well as physicochemical properties by introduction of fluorine atom (s). We describe the discovery stories of three examples in our laboratory, i.e. amidoflumet, a new trifluoromethanesulfonanilide with high miticidal activity against various house dust mites, Metofluthrin, a potent new fluorinated pyrethroid with extremely high knockdown activity against various mosquitoes, and a new α-pyrone compound, 3- [1R-trans- (2-trifluoromethyl) cyclopropane carbonyl] -4-hydroxy-6-methyl-2-pyrone with outstanding insecticidal activity against Blattella germanica.View full abstractDownload PDF (931K) -
Kei Sakamoto, Hisao Nemoto2007 Volume 65 Issue 6 Pages 626-629
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSDownload PDF (488K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese], [in Japane ...2007 Volume 65 Issue 6 Pages 630
Published: June 01, 2007
Released on J-STAGE: October 20, 2010
JOURNAL FREE ACCESSDownload PDF (203K)
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