Search results for: Shigeru Ohba

Items from 1 to 20 out of 26 results

article

Stereoselective construction of cis-decalin framework via radical domino cyclization

Eriko Suzuki, Minoru Ueda, Shigeru Ohba, Takeshi Sugai, more

Tetrahedron Letters > 2013 > 54 > 12 > 1589-1592

Steroids with A/B cis-decalin moiety and various bioactivities have attracted many synthetic chemists as target molecules and development of efficient methodology providing cis-decalins has been desired. A stereoselective domino cyclization via Mn(OAc) ₃ and Cu(OTf) ₂ -mediated radical reaction was found to be effective to construct cis-decalin framework.

article

Three derivatives of 4‐fluoro‐5‐sulfonylisoquinoline

Shigeru Ohba, Noriaki Gomi, Tadaaki Ohgiya, Kimiyuki Shibuya

Acta Crystallographica Section C > 68 > 10 > o427 - o430

In 4‐fluoroisoquinoline‐5‐sulfonyl chloride, C₉H₅ClFNO₂S, (I), one of the two sulfonyl O atoms lies approximately on the isoquinoline plane as a result of minimizing the steric repulsion between the chlorosulfonyl group and the neighbouring F atom. In (S)‐(−)‐4‐fluoro‐N‐(1‐hydroxypropan‐2‐yl)isoquinoline‐5‐sulfonamide, C₁₂H₁₃FN₂O₃S, (II), there are two crystallographically independent molecules (Z...

article

A new NF-κB inhibitor based on the amino-epoxyquinol core of DHMEQ

Tsuyoshi Saitoh, Chika Shimada, Masatoshi Takeiri, Mitsuhiro Shiino, more

Bioorganic & Medicinal Chemistry Letters > 2010 > 20 > 19 > 5638-5642

The amino-epoxyquinols 6a and 6b were synthesized as soluble derivatives of an NF-κB inhibitor DHMEQ (1). In spite of the opposite configuration from 1, 6b rather than 6a affected the deactivation of NF-κB, based on NO secretion and MALDI-TOF MS analysis. It was indicated that 6b inhibited the activation by different manner from that of 1.

article

Highly Diastereoselective 1,4-Addition of an Organocuprate to Methyl α- d -Gluco-, α- d -Manno-, or α- d -Galactopyranosides Tethering an α,β-Unsaturated Ester. Novel Asymmetric Access to β-C-Substituted Butanoic Acids

Kiichiro Totani, Takayuki Nagatsuka, Shuhei Yamaguchi, Ken-ichi Takao, more

The Journal of Organic Chemistry > 2001 > 66 > 18 > 5965 - 5975

article

In Situ X-ray Observation of Pedal-like Conformational Change and Dimerization of trans -Cinnamamide in Cocrystals with Phthalic Acid

Shigeru Ohba, Hiroyuki Hosomi, Yoshikatsu Ito

Journal of the American Chemical Society > 2001 > 123 > 26 > 6349 - 6352

article

First isolation of tautomeric isomers of 4-isopropyltropolone as inclusion complex crystals

Koichi Tanaka, Ryoji Nagahiro, Shigeru Ohba, Makoto Eishima

Tetrahedron Letters > 2001 > 42 > 5 > 925 - 929

Tautomeric isomers of 4-isopropyltropolone have been isolated as inclusion complex crystals and their crystal structures have been elucidated by X-ray analyses.

article

Solid-State and Solution Photolyses of Tetracyanobenzene with Benzyl Cyanides or Benzyl Alcohols

Yoshikatsu Ito, Hironari Nakabayashi, Shigeru Ohba, Hiroyuki Hosomi

Tetrahedron > 2000 > 56 > 37 > 7139-7152

Intermolecular photoreactions of tetracyanobenzene (TCNB) with benzyl cyanide (BzCN), benzyl alcohol (BzOH) and various others were investigated in the solid state (cocrystal) and in solution. The new solid-state photocoupling reaction found for the cocrystal TCNB.BzCN, giving a stilbene derivative followed by the solution isomerization into an isoindole derivative, is a very limited reaction. On...

article

Compelled Orientational Control of the Solid-State Photodimerization of trans-Cinnamamides: Dicarboxylic Acid as a Non-covalent Linker

Yoshikatsu Ito, Hiroyuki Hosomi, Shigeru Ohba

Tetrahedron > 2000 > 56 > 36 > 6833-6844

The 2:1 hydrogen-bonded cocrystals 1a·ox, 1a·su, 1a·pht, 1a·fu, 1b·ox, 1c·ox, 1d·ox between trans-cinnamamides (1a–1d) and dicarboxylic acids (ox, su, gl, fu, pht) were prepared and characterized by IR and powder X-ray techniques. The crystal structures of 1a·pht, 1a·ox and 1a·fu were solved by single crystal X-ray diffraction. Phthalic acid (pht) caused β-type photodimerization of trans-cinnamamide...

article

Mechanochemical Reaction of Polymeric Oxovanadium(IV) Complexes with Schiff Base Ligands Derived from 5-Nitrosalicylaldehyde and Diamines

Masanobu Tsuchimoto, Gakuse Hoshina, Naoki Yoshioka, Hidenari Inoue, more

Journal of Solid State Chemistry > 2000 > 153 > 1 > 9-15

Light brown [VO(5-NO ₂ salen)]·2H ₂ O (1; H ₂ (5-NO ₂ salen)=N,N′-di-5-nitrosalicylidene-1,2-ethanediamine) and orange [VO(5-NO ₂ sal-meso-stien)]·0.5H ₂ O (2; H ₂ (5-NO ₂ sal-meso-stien)=N,N′-di-5-nitrosalicylidene-(R,S)(S,R)-1,2-diphenyl-1,2-ethanediamine) which have linear chain structures in the solid state turn dark brown and yellow-brown,...

article

Cleavage of the C-N bond of a peptide group by a copper(II)-peroxide adduct with an η ¹ -coordination mode

Satoshi Nishino, Mami Kunita, Yoshiyuki Kani, Shigeru Ohba, more

Inorganic Chemistry Communications > 2000 > 3 > 3 > 145-148

We have obtained clear evidence that a copper(II)-peroxide adduct with an η ¹ -coordination mode can cleave the C-N bond of a peptide group and hydroxylate the alkyl group nearby; this may provide helpful information for elucidation of the reaction mechanism of PAM, peptidylglycine α-amidating monooxygenase.

article

Monomeric and polymeric structures of oxovanadium(IV) complexes with Schiff base ligands derived from (R,R)-2,4-pentanediamine - Synthesis and crystal structure

Masanobu Tsuchimoto, Ryuichi Kasahara, Kiyohiko Nakajima, Masaaki Kojima, more

Polyhedron > 1999 > 18 > 23 > 3035-3039

New tetradentate Schiff base-oxovanadium(IV) complexes which have electron donating or withdrawing groups at the 5-position of the salicylaldehyde moieties, [VO{Xsal-(R,R)-2,4-ptn}] (H ₂ {Xsal-(R,R)-2,4-ptn}: N,N'-di-Xsalicylidene-(R,R)-2,4-pentanediamine; X=5-MeO (methoxy), 5-Br, and 5-NO ₂ ) were prepared. The structures and redox potentials for the V(V)/V(IV) couple of the complexes...

article

Interaction between the peroxide ion and acetato moiety of the ligand system in a cobalt complex with a binucleating ligand

Yumiko Sasaki, Teruyuki Kobayashi, Hideki Masuda, Hisahiko Einaga, more

Inorganic Chemistry Communications > 1999 > 2 > 6 > 244-246

Reaction between Na ₃ H ₂ (HXTA) and Na ₃ CO(CO ₃ ) ₃ in an aqueous solution gave a binuclear cobalt(III) complex, Na ₂ Co ₂ (HXTRA), where in the (HXTRA) ⁴ ^- ligand one of the four acetate arms of the (HXTA) ⁵ ^- ligand is lost; H ₅ (HXTA) denotes N,N'-(2-hydroxy-5-methyl-1,3-xylylene)bis(N-carboxymethylglycine)...

article

Interaction between peroxide ion and phenol group which are coordinated to the same iron(III) ion

Sayo Ito, Yoshihiro Ishikawa, Satoshi Nishino, Teruyuki Kobayashi, more

Polyhedron > 1998 > 17 > 25-26 > 4379-4391

We have prepared several new iron(III) complexes with ligands which contain a phenol group; these are tetradentate [(X-phpy)H, X and H(phpy) represent the substituents on the phenol ring and N,N-bis(2-pyridylmethyl)-N-(2-hydroxybenzyl)amine, respectively] and pentadentate ligands [(R-enph-X)H; R=ethyl(Et) or methyl(Me) derivative and H(Me-enph) denotes N,N-bis(2-pyridylmethyl)-N _- methyl-N...

article

Synthesis of the C ₁ ₇ -C ₂ ₇ Fragment of Bryostatin 3

Tetsuo Obitsu, Ken Ohmori, Yasuyuki Ogawa, Hiroyuki Hosomi, more

Tetrahedron Letters > 1998 > 39 > 40 > 7349-7352

The key synthetic intermediate corresponding to the C17 - C27 positions of bryostatin 3, has successfully been synthesized. The newly constructed stereogenic centers were unambiguously confirmed by X-ray crystallographic analysis.

article

Stereoselective chlorination of steroidal 5,6-Olefin by an electrochemical method; A convenient synthesis of blattelastanoside B

Shojiro Maki, Katsuhiro Konno, Shigeru Ohba, Hiroaki Takayama

Tetrahedron Letters > 1998 > 39 > 21 > 3541-3542

Stereoselective chlorination of cholesterol (1) was achieved by an electrochemical method to give a dichloride 2 and a cholohydrin 3. Using this procedure, blattelastanoside B (6), an aggregation pheromone of the German cockroach, was synthesized from β-sitosterol (5) in short steps.

article

DNA degradation by the copper(II) complex with tripodal-ligands containing peptide group

Teruyuki Kobayashi, Takashi Okuno, Toshio Suzuki, Mami Kunita, more

Polyhedron > 1998 > 17 > 9 > 1553-1559

Copper-based transition metal complexes which perform single-strand scission of DNA in a site-specific manner have been designed. The complexes Cu(dpg) ⁺ and Cu(dpgt)Cl ⁺ (H(dpg) and (dpgt) represent bis(2-pyridylmethyl) derivatives of glycylglycine and glycylglycylglycine, respectively), were prepared in this study and its crystal structures were determined. We have found that Cu(dpgt)Cl...

article

Synthetic Studies on Manzamine A: Construction of the Tetracyclic ABCE Ring Substructure I

Shouming Li, Shosuke Yamamura, Hiroki Hosomi, Shigeru Ohba

Tetrahedron Letters > 1998 > 39 > 17 > 2601-2604

The synthesis of the tetracyclic ABCE ring, which bears the crucial 13-membered azacycle, of manzamine A is described.

article

Polyoxypeptin Isolated from Streptomyces: A Bioactive Cyclic Depsipeptide Containing the Novel Amino Acid 3-Hydroxy-3-methylproline

Kazuo Umezawa, Kumi Nakazawa, Toshio Uemura, Yoko Ikeda, more

Tetrahedron Letters > 1998 > 39 > 11 > 1389-1392

Polyoxypeptin, a potent inducer of apoptosis in human pancreatic carcinoma cells, was isolated from an ethyl acetate extract of a Streptomyces culture broth. Structural determination by 2D-NMR and X-ray crystallographic analysis revealed that it is a novel cyclic hexadepsipeptide containing five hydroxylated amino acids. The unusual and hitherto unreported amino acid 3-hydroxy-3-methylproline was...

article

Copper(II) compound with long Cu(II)-phenolic oxygen atom bonding as galactose oxidase model

Sayo Ito, Satoshi Nishino, Hiroki Itoh, Shigeru Ohba, more

Polyhedron > 1998 > 17 > 10 > 1637-1642

A crystal structure determination of Cu(phpyH)ClClO ₄ CH ₃ OH revealed that the protonated phenolic oxygen atom lies at the apex of a square pyramidal CuN ₄ O arrangement with Cu(II)--O(phenolic) distances of 2.46 and 2.57 9; this is a novel copper(II) model compound for galactose oxidase where the Cu(II)-phenolic oxygen (Tyrosine-495) distance is rather long, 2.69 9, and...

article

Solvent and structural effects on catalase-like function of binuclear manganese(II) compounds with μ-phenoxide bridge

Yumiko Sasaki, Tetsuya Akamatsu, Kazuyoshi Tsuchiya, Shigeru Ohba, more

Polyhedron > 1998 > 17 > 2-3 > 235-242

The structures and ESR spectral properties of binuclear manganese(II) compounds which functionally mimic the bacterial dimanganese catalase enzyme have been developed. These compounds are formulated as [(L ¹ )Mn ₂ X ₂ ]Y(X Cl, Br, CH ₃ COO, C ₆ H ₅ COO, (C ₆ H ₅ ) ₂ HCCOO; Y ClO ₄ , PF ₆ ), [(L ² )Mn...

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Keywords

Η 1 -COORDINATION MODE (1)
4-ISOPROPYLTROPOLONE (1)
ACTIVATION OF DIOXYGEN (1)
ACTIVATION OF PEROXIDE (1)
BINUCLEAR MN(II) COMPLEX (1)
BIOLOGICALLY ACTIVE COMPOUNDS (1)
CATALASE-LIKE-FUNCTION (1)
CINNAMAMIDES (1)
CIS-DECALIN (1)
CLEAVAGE OF PROTEIN (1)
COBALT COMPLEXES (1)
COBALTACYCLOPENTADIENE COMPLEXES (1)
COCRYSTALS (1)
COPPER(II) AND HYDROGEN PEROXIDE (1)
COPPER(II)-PEROXIDE ADDUCT (1)
CRYSTAL STRUCTURE (1)
CRYSTALLINE COMPLEXES (1)
CYANO COMPOUNDS (1)
CYCLIC VOLTAMMETRY (1)
CYCLOBUTADIENE COMPLEXES (1)
DEGRADATION OF ALBUMIN (1)
DEGRADATION OF NUCLEOSIDE (1)
DHMEQ (1)
DICARBOXYLIC ACIDS (1)
DIMETHYLFORMAMIDE (1)
DIOXYGEN AND ALDEHYDE (1)
DNA CLEAVAGE (1)
DOMINO REACTION (1)
DYNAMIC DISORDER (1)
ELECTRON TRANSFER (1)
ELECTRONIC INFLUENCE OF SUBSTITUENTS (1)
EPOXYQUINOL DERIVATIVES (1)
GALACTOSE OXIDASE MODEL (1)
HYDROGEN BOND (1)
HYDROGEN PEROXIDE (1)
INCLUSION CRYSTALS (1)
INTERACTION OF PEROXIDE ION AND PHENOL GROUP (1)
IRON(III)-PEROXIDE ADDUCT (1)
LONG CU(II)-PHENOL BOND (1)
MACROLIDES (1)
MARINE METABOLITES (1)
MECHANOCHEMICAL REACTION (1)
METALLACYCLE COMPLEXES (1)
MN(III) AND FE(III) COMPOUNDS (1)
MN(III) SCHIFF BASE COMPOUNDS (1)
MODEL REACTION FOR PAM ENZYME (1)
MONOMERIC COPPER(II) COMPLEX (1)
MONOMERIC STRUCTURES (1)
NF-ΚB INHIBITOR (1)
ORGANOMETALLIC POLYMER COMPLEXES (1)
OXIDATION OF LIGAND SYSTEM (1)
OXOVANADIUM(IV) COMPLEX. (1)
OXOVANADIUM(IV) COMPLEXES (1)
OXYGENATION BY COPPER(II) COMPLEX (1)
OXYGENATION OF CYCLOHEXANE (1)
PEROXIDE ADDUCT (1)
PHOTOCHEMISTRY (1)
POLYKETIDES (1)
POLYMERIC COMPLEX (1)
POLYMERIC STRUCTURES (1)
RADICAL CYCLIZATION (1)
SOLID-STATE PHOTODIMERIZATION (1)
SOLVENT EFFECT (1)
STEREOSELECTIVE SYNTHESIS (1)
STERIOD (1)
SUPERCOILED DNA (1)
TAUTOMERIC ISOMERS (1)
TRIPODAL-LIGANDS (1)
TRIPODAL-LIGANDS CONTAINING PEPTIDE GROUP (1)
TYROSINE RESIDUE (1)
X-RAY STRUCTURES (1)
Μ-PHENOXIDE BRIDGE (1)
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Data set

Elsevier (23)
ACS (2)
Wiley (1)

Journal

Tetrahedron Letters (8)
Polyhedron (7)
Tetrahedron (3)
Inorganic Chemistry Communications (2)
Acta Crystallographica Section C (1)
Bioorganic & Medicinal Chemistry Letters (1)
Inorganica Chimica Acta (1)
Journal of Solid State Chemistry (1)
Journal of the American Chemical Society (1)
The Journal of Organic Chemistry (1)
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INFONA - science communication portal

Search results for: Shigeru Ohba

Stereoselective construction of cis-decalin framework via radical domino cyclization

Three derivatives of 4‐fluoro‐5‐sulfonylisoquinoline

A new NF-κB inhibitor based on the amino-epoxyquinol core of DHMEQ

Highly Diastereoselective 1,4-Addition of an Organocuprate to Methyl α- d -Gluco-, α- d -Manno-, or α- d -Galactopyranosides Tethering an α,β-Unsaturated Ester. Novel Asymmetric Access to β-C-Substituted Butanoic Acids

In Situ X-ray Observation of Pedal-like Conformational Change and Dimerization of trans -Cinnamamide in Cocrystals with Phthalic Acid

First isolation of tautomeric isomers of 4-isopropyltropolone as inclusion complex crystals

Solid-State and Solution Photolyses of Tetracyanobenzene with Benzyl Cyanides or Benzyl Alcohols

Compelled Orientational Control of the Solid-State Photodimerization of trans-Cinnamamides: Dicarboxylic Acid as a Non-covalent Linker

Mechanochemical Reaction of Polymeric Oxovanadium(IV) Complexes with Schiff Base Ligands Derived from 5-Nitrosalicylaldehyde and Diamines

Cleavage of the C-N bond of a peptide group by a copper(II)-peroxide adduct with an η ¹ -coordination mode

Monomeric and polymeric structures of oxovanadium(IV) complexes with Schiff base ligands derived from (R,R)-2,4-pentanediamine - Synthesis and crystal structure

Interaction between the peroxide ion and acetato moiety of the ligand system in a cobalt complex with a binucleating ligand

Interaction between peroxide ion and phenol group which are coordinated to the same iron(III) ion

Synthesis of the C ₁ ₇ -C ₂ ₇ Fragment of Bryostatin 3

Stereoselective chlorination of steroidal 5,6-Olefin by an electrochemical method; A convenient synthesis of blattelastanoside B

DNA degradation by the copper(II) complex with tripodal-ligands containing peptide group

Synthetic Studies on Manzamine A: Construction of the Tetracyclic ABCE Ring Substructure I

Polyoxypeptin Isolated from Streptomyces: A Bioactive Cyclic Depsipeptide Containing the Novel Amino Acid 3-Hydroxy-3-methylproline

Copper(II) compound with long Cu(II)-phenolic oxygen atom bonding as galactose oxidase model

Solvent and structural effects on catalase-like function of binuclear manganese(II) compounds with μ-phenoxide bridge

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