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Volume 52, Issue 4
Displaying 1-7 of 7 articles from this issue
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Hirochika SAKURAGI, Hiroki ITOH1994 Volume 52 Issue 4 Pages 266-275
Published: April 01, 1994
Released on J-STAGE: January 28, 2010
JOURNAL FREE ACCESSPhenanthrene- and naphthalenecarboxylic esters linked with styrene derivatives exert an intramolecular competitive or exclusive oxetane formation depending upon the linking chain length and site, although the carbonyl addition is not observed in the corresponding intermolecular systems. The reaction is a singlet process involving plural exciplexes. The photochemical and, photophysical observations as well as MO calculations indicate that the new aspect of carbonyl addition arises from an apparent enhancement of reactivity of the ester carbonyl group by interchromophoric link; the link destabilizes the exciplexes with conformations achieved in the intermolecular systems and therefore, the exciplexes preferable for carbonyl addition take an important role.View full abstractDownload PDF (1174K) -
Jitsuo KIJI, Tamon OKANO1994 Volume 52 Issue 4 Pages 276-284
Published: April 01, 1994
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSWater-soluble complex catalysts are useful because of simple separation from the products, high activity, and selectivity. To conduct palladium-catalyzed reactions under liquid-liquid two-phase conditions, water-soluble polyether- or crown ether-substituted phosphines with phase transfer ability have been synthesized and characterized. The following reactions in aqueous media catalyzed by the water-soluble phosphine complexes of palladium are surveyed. (1) Hydrogenolysis of allylic halides with formate proceeds smoothly under liquid-liquid or liquid-solid two-phase conditions and 1-olefins are formed. In the two-phase catalysis the palladium complex itself plays a role of a phase transfer agent and a mechanism of inverse phase transfer process has been proposed. Benzylic halides are reduced similarly. (2) Allylic and benzylic halides are carbonylated under atmospheric pressure in aqueous NaOH/organic solvent system to afford β, γ-unsaturated acid and phenylacetic acid, respectively. (3) The reaction of bromoarenes possessing electron-withdrawing groups with ethylene (the Heck reaction) is also possible in an aqueous phase.View full abstractDownload PDF (1161K) -
Yasuko KAMOCHI, Tadahiro KUDO1994 Volume 52 Issue 4 Pages 285-294
Published: April 01, 1994
Released on J-STAGE: January 28, 2010
JOURNAL FREE ACCESSRecent study in this laboratory is reviewed The single electron donor ability of samarium diiodide (SmI2) can be enhanced with ligands around of Sm (II) when a sufficient electron is supplied from ligands. Mechanistic consideration of this enhancement led us to find that carboxylic acid, ester, amide, nitrile and the other functionalities were rapidly reduced with SmI2 in the presence of base, acid and water as ligands at room temperature in good yields. Particularly, these systems reduced directly carboxylic acid into alcohol and SmI2-85% phosphoric acid system reduced aromatic primary amide to aldehyde in good yield Pyridines were similarly reduced to piperidines with SmI2-base or water system and aromatic nucleus of phenol derivatives was rapidly reduced with SmI2-base system Furthermore, carboxylic acid, ester, amide and nitrile were rapidly reduced with Sm or Yb metal-hydrochloric acid system.
The striking characteristic of these reduction is mild conditions, short reaction time (within a few secondsminutes), high yield of reductive products and one pot reaction with facile method.View full abstractDownload PDF (1287K) -
Hiizu IWAMURA1994 Volume 52 Issue 4 Pages 295-307
Published: April 01, 1994
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThere are two approaches toward the establishment of macroscopic spins for organic molecules. One is the exploration of persistent free radicals (S=1/2) that will have ferromagnetic interradical exchange coupling in crystalline states. While this approach has led to the discovery of well characterized organic ferromagnets, their Curie temperatures (Tc) are limited to sub-liquid-helium temperatures. Alternatively, design and synthesis of super-high-spin (S>>1/ 2) organic molecules have been studied. In principle, parallel alignment of two spins can become favored in non-Kekulé systems. One of the highlights of the oligomers and polymers obtained by repeating such units is the synthesis and characterization of a strongly paramagnetic nonacarbene (S=9). The two-dimensional network alignment of spins has been demonstrated to be most promising as high Tc molecular ferromagnets. Some non-Kekulé molecules were found by EPR spectroscopy and magnetic susceptibility/magnetization measurements to violate Hund's rule, thereby being disqualified as the units for super-high-spin polymers.View full abstractDownload PDF (1528K) -
Juzo NAKAYAMA1994 Volume 52 Issue 4 Pages 308-317
Published: April 01, 1994
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSIntramolecular reductive carbonyl coupling of 3-thiapentane-1, 5-diones (diketo sulfides) with a low-valent titanium reagent, prepared from TiCl4 and Zn powder in THF, at 0°C or lower temperatures produces thiolanediols in good yields, while the reduction at room temperature or higher temperatures affords dihydro-thiophenes. The both compounds are converted to the corresponding thiophenes in high yields by acid-catalyzed dehydration or dehydrogenation with DDQ, thus providing a new thiophene synthesis. The new method is very versatile and allows the preparation of a wide variety of structurally interesting thiophenes, including highly congested 3, 4-di-t-butyl-, 3, 4-dineopentyl-, and 3, 4-di-1-adamantylthiophenes, angle-strained 1, 2, 4, 5-tetrahydrodicyclobuta [b, d] thiophene, parent “nonclassical” thienothiophene, and α, β-type thiophene oligomers. Conversion of the foregoing congested thiophenes to other congested molecules such as furan, pyrrole, selenophene, benzene, naphthalene, pyridazine, alkene, and thiete derivatives is described. Structural features of highly congested benzene derivatives are also touched. Finally, application to selenophene synthesis is described.View full abstractDownload PDF (1162K) -
Yoshiharu MATSUBARA, Akiyoshi SAWABE1994 Volume 52 Issue 4 Pages 318-327
Published: April 01, 1994
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSSince 1980's we have been investigating biologically active compounds in citrus fruit peels. We have successfully isolated eighty-five compounds including hitherto unreported thirty-eight new compounds. They were flavonoid glycosides, phenyl propanoid glycosides, terpenoids, terpenoid glycosides, limonoid glycosides, alkyl glycosides, compounds containing nitrogen, and cyclic peptides. In this manuscript, our studies are briefly reviewed focussing on the isolation and relationship between the structures of the compounds and their biological activity.View full abstractDownload PDF (1109K) -
[in Japanese], [in Japanese]1994 Volume 52 Issue 4 Pages 328
Published: April 01, 1994
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSDownload PDF (168K)
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