Hyuma Masu

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The total syntheses of tetrapeptides tubulysins D (1 b), U (1 c), and V (1 d), which are potent tubulin polymerization inhibitors, are described. The synthesis of Tuv (2), an unusual amino acid constituent of tubulysins, includes an 1,3-dipolar cycloaddition reaction of chiral nitrone D-6 derived from D-gulose with N-acryloyl camphor sultam (-)-9 employing(More)
[reaction: see text]. Cycloaddition of aziridines with isocyanates proceeded smoothly in the presence of a nickel catalyst, and five iminooxazolidine derivatives were isolated in good yields. The best result was obtained when the reaction was carried out in the presence of NiI2, and a longer reaction time allowed the isomerization of the iminooxazolidine to(More)
We constructed a novel molecular conformational alteration system with an N-aryl-N-phenylacetamide structure, in which the N-aryl group consists of a hydroquinone-p-quinone system as a redox-dependent aromatic trigger. The amide conformation depended on the oxidation state of the aryl group, and the two states (compounds 2 and 3) were reversibly converted(More)
The [5 + 2] cycloaddition reaction of 2-vinylaziridines with sulfonyl isocyanates proceeded smoothly under mild conditions, and various cyclic ureas were isolated in high yields. The remarkable solvent effect on the reaction was observed, and the preferential formation of the seven-membered ring occurred when the reaction was carried out in CH(2)Cl(2). The(More)
The crystal structures and dynamic behavior in solution of aromatic amides containing terphenyl groups were revealed by X-ray crystallographic analysis and VT-NMR measurements. Controlling the synthetic yield and molecular shape of the macrocycles with intramolecular aromatic-aromatic interactions was successfully achieved.(More)
Novel optically active axially chiral amino acid and amino alcohols have been synthesized efficiently via lactam ring-opening, with the aid of an optically active alcohol, amidoaza[5]helicene 5, which has been readily prepared by an additive-ligand-free Pd catalyzed domino coupling reaction in a single step. The stereostructures of these chiral molecules(More)
A range of bromothiophenes reacted with lithium boranato(tert-butyl)methylphosphide in the absence of transition-metal catalysts under mild conditions to provide the same 2,5-disubstituted and 2-monosubstituted products regardless of the substitution patterns of the starting bromothiophenes.
The title compound, C17H18N2S2, exhibits a trans-trans-trans-gauche(+) (tttg (+)) conformation with regard to the NH-CH2-CH2-CH2-NH bond sequence. In the crystal, mol-ecules are connected by N-H⋯S=C and C-H⋯S=C hydrogen bonds, forming a herringbone arrangement along the c-axis direction. The two thioamide groups make dihedral angles of 43.0 (2) and 33.1(More)
A triple helicate, having a macrocyclic aromatic amide structure, was synthesized in high yield because of a preorganized component of the tertiary benzenetrianilide moieties in a propeller-like syn conformation at both ends. The helicity was derived from tilted T-shaped aromatic-aromatic (CH-pi) interactions between each of the N-phenyl rings. [structure:(More)