Kouhei Toyooka

Synthesis of the naphthalenecarboxylic acid derivative obtained from neocarzinostatin (NCS): a structure revision

Abstract The structure of the naphthalenecarboxylic acid derivative obtained from neocarzinostatin (NCS) was revised as methyl 2-hydroxy-7-methoxy-5-methyl-1-naphthalenecarboxylate ( 2a ) by its synthesis.

Synthesis of nitrated oligo-N-methylpyrrole carboxamide derivatives and their photochemical DNA cleaving activities

Abstract Synthesis of various nitrated oligo-N-methylpyrrolecarboxamide derivatives and their DNA cleaving activities under UV-A irradiation were described.

Synthesis of novel 1,2,4-triazole-containing oligopeptides

Novel 1,2,4-triazole-containing oligopeptides (12-17) were synthesized from 1-methyl-3-nitro-1,2,4-triazole-5-carboxylic acid (10)

Synthesis of halogenated oligo-N-methylpyrrole-carboxamide derivatives and their photochemical DNA cleaving activities

Synthesis of various halogenated oligo-N-methylpyrrole- carboxamide derivatives and their DNA cleaving activities under UV-A irradiation were described

Synthesis of 5-(substituted phenyl) 4-acetyl-2-methylthio-Δ2-1,3,4-thiadiazolines and their oxidation with potassium permanganate

The reaction of aldehyde methylthio (thiocarbonyl) hydrazones (2) with acetic anhydride or acetyl chloride gave 5-(substituted phenyl) 4-acetyl-2-methylthio-Δ2-1,3,4-thiadiazolines (3). Oxidation of compounds (3) with potassium permanganate in acetic acid furnished 5-aryl-2-methylsulphonyl-1,3,4-thiadiazoles (4), 4-acetyl-5-aryl-2-methylsulphonyl-Δ2-1,3,4-thiadiazolines (5), and 4-acetyl-5-aryl-2-methylsulphonyl-Δ2-1,3,4-thiadiazoline 1,1-dioxides (6).

Synthesis of 2,5-disubstituted 3-(4-chlorobenzoyl)-2,3-dihydro-2-methyl-1,3,4-thiadiazole derivatives

2-Substituted 3-(4-chlorobenzoyl)-2,3-dihydro-5-methylthio-1,3,4-thiadiazoles (3) were used as key intermediates to prepare 2,5-disubstituted 3-(4-chlorobenzoyl)-2,3-dihydro-1,3,4-thiadiazoles (4) and (7)

Stereoselective S-oxidation of 5-substituted 4-acetyl-Δ2-1,3,4-thia-diazolines: X-ray crystal structure of 4-acetyl-2-acetylamino-5-methy-5-phenyl-Δ2-1,3,4-thiadiazoline 1-oxide

N.m.r. spectroscopy and X-ray crystallography show that oxidation of 5-substituted 4-acetyl-2-acetylamino-Δ2-1,3,4-thiadiazolines with m-chloroperbenzoic acid gives the corresponding Δ2-1,3,4-thiadiazoline 1-oxides; the novel reactions of the product (2a) are also described.

A new approach for convenient one-pot synthesis of 5-(1-oxidopyridyl)- and 5-(1-oxidoquinolyl)-2-alkylsulphonyl-1,3,4-thiadiazoles

Acetylation of pyridine-4-carbaldehyde methylthio(thiocarbonyl)hydrazone (1a) with acetic anhydride gave 4-acetyl-2-methylthio-5-(4-pyridyl)-4,5-dihydro-1,3,4-thiadiazole (2). Oxidation of compound (2) with 30% hydrogen peroxide in acetic acid furnished 2-methylsulphonyl-5-(1-oxido-4-pyridyl),-1,3,4-thiadiazole (3a). 2-Alkylsulphonyl-1,3,4-thiadiazoles (3a–h) having 1-oxido-2-pyridyl, 1-oxido-3-3-pyridyl, 1-oxido-4-pyridyl, 1-oxido-2-quinolyl, and 1-oxido-4-quinolyl groups at the 5-position were obtained in good yields from the corresponding pyridine-(1a–f) and quinoline-carbaldehyde (1g) and (1h) alkylthio(thiocarbonyl)hydrazones by a one-pot synthesis. A reaction pathway from compound (2) to compound (3a) is also described.