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Volume 57, Issue 9
Displaying 1-8 of 8 articles from this issue
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Tadashi KATOH1999 Volume 57 Issue 9 Pages 736-748
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThis review describes the total synthesis of natural products involving kopsine, popolophuanone E, hydantocidin, and huperzine A, all of which possess not only unique structural features but also prominent biologically properties. The first total synthesis of the heptacyclic indole alkaloid kopsine was accomplished by employing intramolecular Diels-Alder reactions and Pummerer-type cyclization as the key steps. In the synthetic studies of popolophuanone E, a topoisomerase- II inhibitor from a marine sponge, popolophuanone E trimethyl ether was successfully synthesized by a method featuring the biogenetic-type annulation. The synthetic pathway to hydantocidin, a novel herbicide from Streptomyces sp., has been developed based on the plausible biosynthetic pathway. Total syntheses of both enantiomers of huperzine A, a powerful selective inhibitor of acetylcholinesterase, were accomplished by employing two types of methods which involves the tandem Cinchona alkaloids-promoted asymmetric Michael addition/aldol reaction and the palladium-catalyzed asymmetric bicycloannulation. Furthermore, the novel fluorinated huperzine A analogues were synthesized in order to explore the structure-activity relationships.View full abstractDownload PDF (1480K) -
Hideyuki SHINMORI, Atsuhiro OSUKA1999 Volume 57 Issue 9 Pages 749-762
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSRecent advances in the synthesis of covalently linked multiporphyrin arrays are summarized with particular emphasis on those with well-defined geometries and with novel and interesting properties. Of these, 1) aromatic-group bridged porphyrin arrays have been proved to be useful for defining geometries of the porphyrin arrays without alternation of physical properties of porphyrin subunits, 2) ethynyl-group bridged porphyrin arrays that are relatively easy to make by palladium-catalyzed reactions display significant changes in their optical and electrochemical properties particularly when the ethynyl groups are attached at the meso-positions of porphyrins, and 3) meso-meso linked multiporphyrin arrays are promising in view of their unique optical properties, easy extension to higher oligomers, and relatively high solubility.View full abstractDownload PDF (1514K) -
Keiko YAMAMOTO, Sachiko YAMADA1999 Volume 57 Issue 9 Pages 763-774
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSSystematic studies of organocuprate conjugate additions to γ-chiral acyclic enones and enoates, which have two alkyl substituents at r-position, led us to generalize diastereofacial selectivity of these reactions. The diastereoselectivity depended on the double-bond geometry, the configuration at the γ -position, and the reaction conditions. In reactions without activating additives, cuprate added to the same face of isomeric E- and Z-enones with high diastereoselectivity. Addition of TMSCl together with HMPA not only accelerated the addition reaction but also completely changed the pattern of it-facial selectivity. In reactions containing those additives, cuprates added to isomeric E- and Z-enones with reverse facial selectivity. Under the latter conditions, even the enoates reacted efficiently with similarly reverse and high facial selectivity. On the basis of these results, we postulated a general rule to predict diastereofacial selectivity of cuprate conjugate additions to γ-alkyl compounds. This rule was demonstrated to be applicable to other γ-chiral compounds with γ-alkoxy, γ-phenyl, or γ-ureido substituent.View full abstractDownload PDF (1424K) -
Kazuhiro NAGAYAMA, Isao SHIMIZU, Akio YAMAMOTO1999 Volume 57 Issue 9 Pages 775-783
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSAcyclic and cyclic carboxylic anhydrides oxidatively add to zerovalent palladium complexes having tertiary phosphines with carbon-oxygen bond cleavage to give corresponding acyl (carboxylato) palladium complexes, which subsequently react with atmospheric dihydrogen at room temperature to form aldehydes and carboxylic acids. Application of these results led us to the discovery of novel aldehyde synthesis by hydrogenation of carboxylic anhydrides catalyzed by palladium complexes. Furthermore we have developed atom-efficient and environmentally benign, direct hydrogenation of carboxylic acids to corresponding aldehydes in the presence of trimethylacetic anhydride catalyzed by palladium complexes.View full abstractDownload PDF (1101K) -
Tadashi EGUCHI, Kenji ARAKAWA, Katsumi KAKINUMA1999 Volume 57 Issue 9 Pages 784-797
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSTotal synthesis of archaeal 36- and 72-membered macrocyclic membrane lipids and their model compounds using several methodologies are described. The first was the diacetylene coupling known as Glaser reaction for construction of macrocyclic phosphodiester model compounds. For the synthesis of archaeal macrocyclic membrane lipids, we made use of two methodologies for the macrocyclization. The ultimate intramolecular dicarbonyl coupling using low-valent titanium successfully provided the 36- and 72-membered macrocyclic compounds with 50-70% yield. In addition, a new and efficient approach to the macrocyclic lipids using olefin metathesis allowed us to successfully prepare both 36-and 72-membered compounds from the same precursor by using the proper conditions.View full abstractDownload PDF (1445K) -
Yasushi KAWAI, Atsuyoshi OHNO1999 Volume 57 Issue 9 Pages 798-804
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThe asymmetric reduction of keto esters accompanied by simultaneous dynamic and static resolution of chiral centers can be achieved by using a novel enzyme, YKER- I (Yeast Keto Ester Reductase- I). This reaction affords the corresponding hydroxy esters having three chiral centers. In the reduction of sec-alkyl 2-methyl-3-oxobutanoates, YKER-I affords the corresponding (2R, 3S, 1′R) -hydroxy esters selectively. Particularly, the reduction of 1, 3-dithianyl derivative affords the (2R, 3S, 1′R) -hydroxy ester in more than 95% purity out of possible eight stereoisomers. The reduction of dimethyl 2-acetyl -3-methylglutarate with this enzyme gives the corresponding (2R, 3R, 1′S) -hydroxy ester in more than 98% purity out of possible eight stereoisomers. This enzyme can introduce the three consecutive chiral centers in one stage of the reaction. No enzyme has been reported on the discrimination of remote and multichiral centers in acyclic compounds that have flexible skeletons.View full abstractDownload PDF (960K) -
Hideho OKAMOTO1999 Volume 57 Issue 9 Pages 805-812
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSRecent developments regarding microreactors of which reaction volume is at μl order are reviewed from the viewpoint of system design for laboratory automation which is useful for process chemistry. Physical and chemical phenomena at μm level (size effects), structural elements, and fabrication methods concerning microreactors are summarized. Applied reaction examples classified into seven categories are also surveyed. The advantages of microreactors are (1) easy of rapid and precise control of temperature, which is helpful in obtaining of heat-unstable compounds, (2) high reaction rate, (3) high yield of reaction products (the author's hypothesis) and (4) easy of scale-up of reaction volume without complicated calculations in chemical engineering. The productivity of chemical compounds by microreactors is much enough for cost-effective fine chemicals. The importance of combination of computer-aided synthesis design and microreactors is also pointed out to swiftly validate the candidate reaction routes presented. In conclusion, microreactors have great potential for serving as a powerful tool for organic synthesis research.View full abstractDownload PDF (1108K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese]1999 Volume 57 Issue 9 Pages 813
Published: September 01, 1999
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSDownload PDF (170K)
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