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Volume 51, Issue 8
Displaying 1-9 of 9 articles from this issue
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Kiyomi KAKIUCHI1993 Volume 51 Issue 8 Pages 692-702
Published: August 01, 1993
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSNovel skeletal transformations of bicyclo [4.2.0] octan-2-ones via 8-membered-ring carbocation intermediates have been developed. The acid-catalyzed rearrangement of 5, 6-disubstituted bicyclooctanones is a highly-efficient method for synthesis of polycyclopentanoids such as diquinanes, angularly-fused triquinanes, spiro-annulated triquinanes, and tetraquinanes. The reaction of 5-6-4 fused ring ketones with acid in acid anhydride is a unique method for construction of 8-membered-ring compounds such as bicyclo [6.3.0] undecanes. The acid-catalyzed rearrangement of 6-substituted bicyclooctanones provides an excellent method for synthesis of bicyclo [4.2.1] nonanes. Utility of our novel method has been demonstrated by synthetic studies of terpenoids such as 5-oxosilphiperfol-6-ene, silphiperfol-6-ene, 3-oxosilphinene, and mediterraneol B.View full abstractDownload PDF (1300K) -
Tsuneo SATO1993 Volume 51 Issue 8 Pages 703-717
Published: August 01, 1993
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSThis article deals with synthetically useful reactions based on organotin (IV) triflates [R2Sn(OTf)2]. Topics included are (1) development of R2Sn(OTf)2, (2) reaction of carbonyl compounds or their acetals with silylated nucleophiles or thiostannane nucleophiles, (3) Mukaiyama-Michael addition reaction of α, β-unsaturated ketones and enol silyl ethers and its application to new Robinson annulation reaction, and (4) practical method for constructing contiguous quaternary carbon centers.View full abstractDownload PDF (1501K) -
Keisuke SUZUKI, Takashi MATSUMOTO1993 Volume 51 Issue 8 Pages 718-732
Published: August 01, 1993
Released on J-STAGE: January 28, 2010
JOURNAL FREE ACCESSRecent study in this laboratory is reviewed. Combination of group 4 metallocene dichloride (Cp2MCl2 : M= Zr, Hf) and silver salt (AgX : X = ClO4, OTf etc.) is a particularly effective reagent for activating glycosyl fluoride, which offers a new and efficient method for O-glycoside synthesis, which made us to succeed in the first total synthesis of mycinamicin macrolide antibiotics. Mechanistic consideration of this activation led us to find that the reagent combination in 1 : 2-ratio, rather than the original 1 : 1-ratio, of Cp2MCl2 and AgX engendered further enhanced reactivity. Some of the recent application in oligosaccharide synthesis is listed to show the broad scope of this new glycosidation reaction in natural product synthesis. Furthermore, this combinational reagent offers a powerful basis for aryl C-glycoside synthesis and the total syntheses of three prototypical compounds of this class, vineomycinone B2 methyl ester and gilvocarcin M and V, were successfully carried out by this glycoside activation method.View full abstractDownload PDF (1579K) -
Kiyoshi SAKAI1993 Volume 51 Issue 8 Pages 733-743
Published: August 01, 1993
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSRh (I) -catalyzed cyclization of substituted 4-pentenals into cyclopentanones found first by our laboratory was developed into the highly diastereoselective and enantioselective asymmetric cyclization by using the Rh (I) -complex with chiral ligand such as BINAP, and (+) -DIPMC. Cationic Rh (I) with BINAP afforded the best asymmetric cyclization in chemical yields and enantioselectivity as well as the diastereoselectivity. This cyclization method could be successfully applied for the synthesis of iridomyrmecin and isoiridomyrmecin from (-) -i-monene. In addition, Rh (I) -catalyzed cyclization of oct-6-enal with the cis-cyclohexane-1, 2-dioxy function at C 3-position afforded two conformational diastereomers due to a cis-cyclohexane-1, 2-diol moiety. The interesting findings found by our group are summarized as main topics in this paper.View full abstractDownload PDF (1316K) -
Fuyuhiko MATSUDA1993 Volume 51 Issue 8 Pages 744-753
Published: August 01, 1993
Released on J-STAGE: January 28, 2010
JOURNAL FREE ACCESSThis review mentions the total sytheses of the highly functionalized natural products, pederine, aplasmomycin, and virantmycin. The total synthesis of pederine was accomplished by employing the new method for stereocontrolled formation of N- (α-methoxyalkyl) amide. Based on the novel remote controlled asymmetric redutions of some chiral ketones, the formal total synthesis of aplasmomycin was achieved. The stereospecific total synthesis of virantmycin and its diastereomer were performed by using intramolecular addition reaction of nitrene to olefin, and relative stereochemistry of virantmycin was established unambiguouly.View full abstractDownload PDF (1107K) -
Motokazu UEMURA1993 Volume 51 Issue 8 Pages 754-764
Published: August 01, 1993
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESS(η6-Arene) chromium complexes have some characteristic properties due to the strong electron withdrawing ability and steric bulkiness of tricarbonyl chromium group. Their signficant applications have been developed utilizing following effects; 1) nucleophilic addition to the arene ring, 2) lithiation of the aromatic hydrogen, 3) stabilization of benzylic carbanion, 4) stabilization of benzylic carbocation, and 5) steric hindrance of Cr (CO)3 group. Also, (arene) chromium complexes can exist in two enantiomeric forms, when the phenyl ring is substituted at ortho- or meta-position by different substituents. This review focuses on our investigations and the related works of (η6-arene) chromium complexes in organic synthesis.View full abstractDownload PDF (1369K) -
Substituted Aromatic Compounds from Aliphatic PrecursorsNaoshi IMAKI, Mitsuhiko TAMURA, Haruo KATSUMATA, Takemi NAKANOME1993 Volume 51 Issue 8 Pages 765-770
Published: August 01, 1993
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSNew synthetic method of benzofuranol compound (2, 3-dihydro-2, 2-dimethyl-7-hydroxybenzofuran) that is used as an important intermediate of low toxic carbamate insecticides, has been developed and established by using the strategy of aromatic compounds from aliphatic precursors. New process comprises following 5 steps; (1) cross aldol condensation of cyclohexanone with isobutyl aldehyde, (2) chlorination of 2-isobuty-lidene-cyclohexanone, (3) dehydrochlorination of 2, 2-dichloro-6-chloro-6- (1-chloroisobutyl) cyclohexanone (aromatization), (4) hydrolysis of 2-chloro-6-isobutylphenol, (5) cyclization of 3-isobutenyl-catechol.View full abstractDownload PDF (583K) -
Hiroshi YAMACHIKA1993 Volume 51 Issue 8 Pages 771-776
Published: August 01, 1993
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSDownload PDF (599K) -
[in Japanese], [in Japanese], [in Japanese]1993 Volume 51 Issue 8 Pages 777
Published: August 01, 1993
Released on J-STAGE: November 16, 2009
JOURNAL FREE ACCESSDownload PDF (160K)
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