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Volume 48, Issue 5
Displaying 1-7 of 7 articles from this issue
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Tetsuo TSUDA, Takao KIYOI, Naoki HASEGAWA, Takeo SAEGUSA1990 Volume 48 Issue 5 Pages 362-369
Published: May 01, 1990
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSTransition metal-catalyzed carbon dioxide fixation into unsaturated hydrocarbons is an important problem. On the basis of two new approaches, i.e., use of reactive substrates of diynes and alkoxyacetylenes and synthesis of a trialkylphosphine ligand containing a pyridyl functional group, we have developed an efficient and selective nickel (0) -catalyzed cycloaddition reaction of acetylenes with carbon dioxide to various 2-pyrones. By the use of aldehydes instead of carbon dioxide, we have also developed a nickel (0) tertiary phosphine complex-catalyzed reaction of diynes and monoynes with aldehydes, which provides synthetic methods of bicyclic 2H-pyrans, functionalized carbo and heterocycles and α, β-enones.View full abstractDownload PDF (971K) -
Masahiko IYODA1990 Volume 48 Issue 5 Pages 370-380
Published: May 01, 1990
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSNew Synthetic methods for preparing highly unsaturated compounds are developed by using the nickel-catalyzed cyclooligomerization of cumulenes, carbenoids, and benzocyclobutadiene, and the nickel-catalyzed Ullmann coupling of organic halides. [3] Cumulenes (butatrienes), which are generated in situ from various precursors, react with nickel (0) complexes to produce [4] radialenes in benzene and THF or [6] radialenes in DMF. The formation of dimers and trimers depends on the solvent used. Reaction of [5] cumulenes (hexapentaenes) with Ni (CO)2 (PPh3)2 yields very unique compounds containing radialene frameworks. Furthermore, reaction of nickel carbenoids proceeds formally as a cyclooligomerization of the carbene center to give [3] -, [4] -, and [5] radialenes. This one-step method has been applied to the synthesis of radialenes containing functional groups. The nickel-catalyzed Ullmann coupling of vinyl halides can be also achieved to give novel π-electron systems. Nickel-mediated synthesis of trimers of benzocyclobutadiene is demonstrated with mechanistic explanation.View full abstractDownload PDF (1236K) -
Kohei TAMAO, Kenji KOBAYASHI, Yoshihiko ITO1990 Volume 48 Issue 5 Pages 381-388
Published: May 01, 1990
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSNickel (0) -mediated intramolecular cyclizations of enynes and diynes have mainly been described. The article includes the following topics. (1) Cyclization of 1, n-enynes and dienynes with isocyanides to produce polycyclic iminocyclopentenes. (2) Cyclization of 1, n-diynes with isocyanides to form polycyclic iminocyclopentadienes. (3) Cyclization of 1, 6-diynes with “silylenes” to produce bicyclic silacyclopentadienes. (4) Cyclization of 1, 7-diynes with hydrosilanes to form 1, 2-dialkylidenecyclohexanes bearing a (Z) -vinylsilane moiety. (5) Cyclization of bis-dienes with hydrosilanes to give 1, 2-divinylcyclopentanes having an allylsilane moiety. Properties, reactivities and synthetic utilities of new ring systems thus obtained are also described.View full abstractDownload PDF (878K) -
Manabu NODE, Kaoru FUJI1990 Volume 48 Issue 5 Pages 389-402
Published: May 01, 1990
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSNitroolefins are versatile synthetic intermediates in organic synthesis because of excellent ability for carbon-carbon bond formation and easy transformation to a variety of functional groups. In the reaction of enolates with chiral nitroolefins, a chiral hetero substituent is replaced by the carbon substituents via addition-elimination process. The scope, limitations, and the mechanism for this type of asymmetric induction will be discussed. The resulting chiral nitroolefins have a wide utility as chiral building blocks for the chiral syntheses of the natural products, such as Aspidosperma, Hunteria, and Physostigma alkaloids, tricyclic diterpenoids and sesquiterpenoids.View full abstractDownload PDF (1520K) -
Shouji IWATSUKI1990 Volume 48 Issue 5 Pages 403-415
Published: May 01, 1990
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSPolymerizations of unsubstituted quinodimethane which is too reactive to be obtainable as condense state, were described in the flash pyrolysis and vapor-coating methods. Chlorine-substituted quinodimethanes were compared with the number of chlorine-substituents. Electron-accepting, substituted quinodimethanes like TCNQ, obtainable as stable crystalline compounds, are not homopolymerizable but copolymerizable with donor monomers like styrene in an alternating fashion. Tetrakis (methoxycabonyl) - and tetrakis (ethoxycarbonyl) -quinodimethane exhibit amphoteric behavior in their alternating copolymerizations. Some quinodimethanes with different two substituents at 7 and 8 positions are homopolymerizable, for instance, anionic polymerization of BCQ occured in living type and gave the polymer with molecular weight above million. Their homopolymerizations also showed an equilibrium behavior which allowed us to determine thermodynamic data for polymerization of those monomers. Their copolymerizations with styrene occurs in random fashion The cross propagation step was studied in detail by means of linear free energy relationship.View full abstractDownload PDF (1542K) -
Yasuhiko MORITA1990 Volume 48 Issue 5 Pages 416-417
Published: May 01, 1990
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESS -
[in Japanese], [in Japanese], [in Japanese], [in Japanese]1990 Volume 48 Issue 5 Pages 418
Published: May 01, 1990
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSDownload PDF (139K)
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