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Volume 59, Issue 9
Displaying 1-7 of 7 articles from this issue
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Syntheses and ApplicationsYoshihiro Matano2001 Volume 59 Issue 9 Pages 834-844
Published: September 01, 2001
Released on J-STAGE: January 22, 2010
JOURNAL FREE ACCESSThe syntheses and reactions of bismuthonium salts and bismuth ylides are reported. Various types of bismuthonium salts bearing a Bi-Csp3, Bi-Csp2, or Bi-Csp bond have been prepared by the Lewis-acid promoted reaction of triphenylbismuth difluoride with organometallic reagents. The bismuthonium salts thus obtained behave as alkyl cation equivalents, alkenyl cation equivalents, and carbene precursors. The bismuth ylides bearing a carbonyl group at the ylidic carbon react with carbonyl compounds to undergo epoxidation, transposition, or ring expansion depending on the structure of the substrates employed. These reaction modes are characteristic of bismuth among the group 15 elements. The stabilized bismuth ylides bearing a highly cross-conjugated ylidic carbon decompose, at an elevated temperature or in the presence of a copper catalyst, to give trisubstituted oxazoles. The observed unique reactivities of the bismuthonium salts and the bismuth ylides are ascribed to the good leaving ability of the triarylbismuthonio group.View full abstractDownload PDF (1851K) -
Tetsuo Jikihara, Akemi Hosokawa2001 Volume 59 Issue 9 Pages 845-854
Published: September 01, 2001
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSIndanofan ((RS) -2-[[2-(3-chlorophenyl) oxiranyl] methyl] -3-eth ylindan-1, 3-dione), a novel class of grass herbicide, was discovered by Mitsubishi Chemical Corporation during the study of oxiran containing herbicidally active compounds. It was introduced into the market in 1999, and is now widely used as the active ingredient for One-shot rice herbicides in Japan. It controls Echinochloa oryzicola of 0 to 2.5 leaf-stage at 100 to 150g a.i./ha for enough periods even at low temperature.
Indanofan is characterized by its unique chemical structure due to indan-1, 3-dione and 2-phenyl substituted oxirane moieties bridged via methylene carbon atom. This paper describes firstly the drug design process for indanofan, lead generation and lead optimization, and secondly the synthesis and manufacturing process of indanofan and its key intermediates, 2-ethylindan-1, 3-dione and 1-chloro-3- (1-chloromethylvinyl) benzene including the oxidation process using high concentration peracetic acid.View full abstractDownload PDF (1640K) -
Controlling Factors on the Regio- and Stereoselectivity in the Oxetane FormationsManabu Abe, Masatomo Nojima2001 Volume 59 Issue 9 Pages 855-865
Published: September 01, 2001
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSWe have explored the regio- and stereoselectivity in the [2+2] photocycloaddition, so-called Paternò-Büchi reaction, of silyl ketene acetals with carbonyl compounds. The structures of the intermediates, i.e. radical cation, exciplex, 1, 4-biradical, have been proposed to be an important factor of controlling the selectivities. This account provides the useful information on the selective synthesis of oxetane derivatives.View full abstractDownload PDF (1928K) -
Kazuhiro Kondo, Yasuoki Murakami2001 Volume 59 Issue 9 Pages 866-878
Published: September 01, 2001
Released on J-STAGE: January 22, 2010
JOURNAL FREE ACCESSIn this review, our recent studies in relation to synthetic organic chemistry based on the N-Ar axis, are embodied, which are divided by content into three sections as follows : (i) development of sufficiently chemoselective N-acylation reagents : a variety of storable N-acetyl-N- (2-trifluo-romethylphenyl) acetamide, N-benzoyl- (2-chlorophenyl) benzamide and N-acyl-N- (2, 3, 4, 5, 6-pentafluorophenyl) methanesufonamide, have been developed after systematic research on the structure-reactivity relationship and were found to serve as N-acylation reagents, exhibiting suffi-ciently better chemoselectivity compared with current N-acylation reagents; (ii) fundamental stud-ies of a chiral axis due to an acyclic imide-Ar Bond : the first example of optically active N-acyl-N- (2-t-butylphenyl) acetamide which possesses axial chirality based on an acyclic imide N-Ar bond rotation, has been found. Furthermore, the relationship between the stability to racemization and the steric and electronic effects, was elucidated; (iii) development of a chiral ligand possessing a N-Ar prochiral axis : our chiral ligand was designed on the following concept. As a chiral ligand design element for asymmetric transition metal catalyst, we use a “N-Ar prochiral axis”. Accordingly, though the N-Ar axis in our ligand is configurationally flexible, “prochiral”, the formation of the metal-our ligand complex should lead to a stable “chiral” N-Ar axis. And if this formation is largely reflected by the asymmetric center in the neighboring group, one of the two diastereomeric complexes due to the N-Ar axis, is expected to be selectively formed. Our synthesized ligands were evaluated with a standard palladium-catalyzed asymmetric allylic substitution and were found to exhibit high selectivity (up to 99% ee).View full abstractDownload PDF (1996K) -
Hideyuki Sugimura, Keiko Sujino2001 Volume 59 Issue 9 Pages 879-891
Published: September 01, 2001
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSA convenient method for the stereocontrolled synthesis of nucleosides has been developed utilizing intramolecular aglycon delivery system. An important feature is to use 1-thioglycosides as glycosyl donor substrates, which can be counted as stable glycosides during modification steps of the carbohydrate moieties as well as introduction step of the pyrimidine base, but, on the other hand, the 1-thioglycosides can work as powerful glycosyl donors when they are treated with an appropriate thiophilic reagent. The suitable activator was found to be Me2S(SMe)BF4. The synthetic applicability is demonstrated by the syntheses of pharmaceutically important deoxynucleosides exemplified as ddC, AZT, FLT, some base-modified nucleosides, isonucleosides, nucleoside antibiotics, and 4'-thionucleosides.View full abstractDownload PDF (1974K) -
Atsushi Kawachi, Kohei Tamao2001 Volume 59 Issue 9 Pages 892-903
Published: September 01, 2001
Released on J-STAGE: January 22, 2010
JOURNAL FREE ACCESSSeveral types of nitrogen-, oxygen-, and sulfur-functionalized silyllithiums have been prepared as the first members of stable and/or well-characterizable functionalized silyl anions. These functionalized silyllithiums can be obtained mainly by tin-lithium exchange reaction of the corresponding silylstannanes with butyllithium and/or by reaction of the corresponding chlorosilanes with lithium. Described herein are also the general aspects of (1) high stability of[(amino) silyl]lithiums, (2) low stability of [(alkoxy)silyl]lithiums, behaving as silylenoid species, (3) low stability of [(arylthio)silyl]lithiums, affording silylenes, (4) structure analyses of the [(amino)silyl]lithiums in solution and in the solid state, (5) [2, 3]-sila-Wittig rearrangement and cyclopropanation reaction of [(allyloxy)silyl]lithiums and the chirality transfer during these reactions, (6) functionalized oligosilane synthesis using [(amino)silyl]lithiums, and (7) synthetic application of (aminosilyl)lithiums as a hydroxy anion equivalent by a combination with the oxidative cleavage of the Si-C bonds.View full abstractDownload PDF (1985K) -
[in Japanese], [in Japanese], [in Japanese], [in Japanese]2001 Volume 59 Issue 9 Pages 904
Published: September 01, 2001
Released on J-STAGE: November 13, 2009
JOURNAL FREE ACCESSDownload PDF (179K)
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