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Volume 58, Issue 4
Displaying 1-8 of 8 articles from this issue
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Hajime Ito, Akira Hosomi2000 Volume 58 Issue 4 Pages 274-284
Published: April 01, 2000
Released on J-STAGE: January 22, 2010
JOURNAL FREE ACCESSThis article presents several synthetic reactions by using a catalyst containing group 11 metals. We recently found an unprecedented reaction between an alkynylsilane and CuCl to produce the corresponding alkynylcopper (I) in DMI (1, 3-dimethy1-2-imidazolidinone). This transformation was applied to the synthesis of alkynyl ketones catalyzed by CuCl. A new and convenient procedure for the stereo- and chemoselective reduction of carbonyl compounds by use of a complex of copper (I) hydride generated from a hydrosilane and a copper (I) salt is described. A new method for the synthesis of enol esters (O-acylated products) from silyl enol ethers by use of a copper (I) salt is also described. An unprecedented cleavage reaction of the silicon-silicon bond in a disilane with a Cu (I) salt and its new 1, 4-addition reaction toward α, β-unsaturated carbonyl compounds in the presence of a catalytic amount of a Cu (I) salt is reported. Thus under these conditions, organosilyl-, hydrido-, alkynyl-, aryl- and heteroarylsilanes were smoothly converted to the corresponding organocopper reagents. Similarly, Au (I) complexes efficiently catalyze the dehydrogenative dimerization of trialkylstannanes and hydrosilylation of aldehydes. The present method provides new synthetic tools.View full abstractDownload PDF (1631K) -
Takahiko Akiyama2000 Volume 58 Issue 4 Pages 285-292
Published: April 01, 2000
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSReported herein is the formation of both heterocycles and carbocycles by means of the nudeophilic attack of the hetero-atom onto the β-silyl carbocation intermediate generated from allylsilane. Thus, on treatment of β-keto ester with allylsilane bearing bulky silyl group in the presence of Lewis acid, [3+2] or [2+2] cycloaddition took place smoothly to afford silyl-substituted tetrahydrofuran or oxetane in good yield.
ZrCl4 mediated [3+2] cycloannulation of allyldiisopropylphenylsilane with α, β-unsaturated diesters proceeded smoothly to afford silyl-substituted cyclopentanes highly stereoselectively in good yields. Subsequent oxidative cleavage of the carbon-silicon furnised cyclopentanols. Allyldiisopropylphenylsilane was found to work effectively as 2-hydroxy-1, 3-dipole equivalent in the [3+2] cycloaddition reactions.
Bronsted acid catalyzed silicon-directed cyclization of allylsilane bearing hydroxy or sulfonamide moiety furnished silyl-substituted tetrahydrofuran or pyrrolidine derivatives stereoselectively in high yields. Chiral synthesis of pyrrolidine was achieved starting from enantiomerically pure aziridines.View full abstractDownload PDF (1046K) -
Kotohiro Nomura2000 Volume 58 Issue 4 Pages 293-305
Published: April 01, 2000
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSThis review summarizes the recent developments in the field of olefin polymerization, especially focuses on the topic by nickel, palladium, iron, cobalt, and ruthenium complex catalysts including the brief summary of this research background. A lot of studies have been explored concerning olefin polymerization by nickel and palladium complex catalysts especially after the discovery of α-diimine coordinated nickel and palladium catalysts reported by Brookhart et al., and these results introduce new possibilities for making new type of olefin-based copolymers by these catalysts. In particular, recent discovery concerning ethylene polymerization by iron and cobalt complexes containing 2, 6-bis (imino) pyridine ligand attracted particular attention due to the exceptionally high catalytic activity, and the contents concerning this topic have also been summarized briefly. We also wish to introduce our recent results concerning olefin polymerization by ruthenium and iron complexes-cocatalyst systems.View full abstractDownload PDF (1745K) -
Toyoji Kakuchi, Makoto Obata, Kazuaki Yokota2000 Volume 58 Issue 4 Pages 306-315
Published: April 01, 2000
Released on J-STAGE: January 22, 2010
JOURNAL FREE ACCESSThe cyclocopolymerization of bis (4-vinylbenzoate) (1) of a chiral diol with styrene has been studied in order to clarify the relationship between chiral template structure and its chirality inductivity. The polymerization was carried out using AIBN as an initiator in dry toluene ([1+styrene] 0 = 0.1 mol·L-1) at 60°C. After removal of the chiral template from the resulting polymer 2, the template-free polymer, i.e., poly [(methyl 4-vinylbenzoate) -co-styrene] (3), showed optical activity, which significantly depended on the chiral template used. When the optically active polymer 3 was obtained, the specific rotations ([α] 435) of the polymer increased with a decrease in the mole fraction of methyl 4-vinylbenzoate unit in the polymer, indicating that the optical activity was attributable to the isolated benzoate diad. According to the exciton chirality method, the CD spectra of polymers 3 indicated that the dextrorotatory polymer 3 had a higher content of (S, S) -racemo benzoate diad over (R, R) -racemo one and the levorotatory polymer 3 was in the reverse situation. The stereoselection was also observed in the radical cyclization using an organotin compounds as a chain transfer reagent. In addition, the stereoisomer distribution of the resulting cyclized unimers indicated that the chiral template inhibited the formation of the unfavorable racemo diad in four possible diads. The calculated heat of formation of cyclized radical by means of semiempirical MO calculation supported the experimental results and gave a model for chirality induction.View full abstractDownload PDF (1391K) -
Toshiyuki Itoh2000 Volume 58 Issue 4 Pages 316-323
Published: April 01, 2000
Released on J-STAGE: January 22, 2010
JOURNAL FREE ACCESSAsymmetric synthesis of two types of partly difluorinated compounds has been accomplished based on the chemo-enzymatic reaction strategy. Optically active 1, 1-difluoro-2, 3- (bishydroxymethyl) cyclopropane has been synthesized through lipase-catalyzed reaction; prochiral diacetate of cis-1, 1-difluoro-2, 3-bis (hydroxymethyl) cyclopropane was converted to the corresponding monoacetate through Alcaligenes sp. lipase-catalyzed hydrolysis with >99% enantiomeric excess. Racemic acetate of trans-1, 1-difluoro-2, 3-bis (hydroxymethyl) cyclopropane was resolved by Pseudomonas sp. lipase-catalyzed hydrolysis successfully. Lipase-catalyzed reaction was employed to resolve bis-difluorocyclopropane derivatives; the first synthesis of optically pure (trans, trans) -2, 2, 5, 5-tetrafluoro-1, 6-bis (hydroxymethyl) bicyclopropane has thus been accomplished. Carbon radicals from allyl O-trimethylsilyl-α-bromo-α, α-difluoroacetal can cyclize onto the olefinic part regiospecifically to give γ-lactols in good yield. The lactols are then converted to the corresponding α, α-difluoro-γ-lactones. Systematic synthesis of multifluorinated-α, α-difluoro-γ-lactones has been accomplished through intramolecular radical cyclization as a key reaction. The synthesis of difluorinated analogue of an insect sex pheromone has been accomplished through intramolecular radical cyclization and lipase-catalyzed reaction.View full abstractDownload PDF (1286K) -
Akihiro Ishii, Koichi Mikami2000 Volume 58 Issue 4 Pages 324-333
Published: April 01, 2000
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSAsymmetric synthesis of organofluorine compounds is an important issue in pharmaceutical chemistry and optoelectronic material science. In this respect, asymmetric catalysis of carboncarbon bond-forming reactions is the most attractive method. Asymmetric catalysis of ene, Mukaiyama-aldol and Friedel-Crafts reactions with fluoral is thus established using chiral binaphthol-derived titanium ((6-Br) -BINOL-Ti) catalysts to provide a practical synthetic route to the organofluorine compounds containing trifluoromethyl group.View full abstractDownload PDF (1519K) -
Yuji Ohashi2000 Volume 58 Issue 4 Pages 334-338
Published: April 01, 2000
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSDownload PDF (995K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese]2000 Volume 58 Issue 4 Pages 339
Published: April 01, 2000
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSDownload PDF (192K)
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