Showing papers by "Hirosuke Yoshioka published in 1977"

Studies on the nitration of m-cresol. A new selective method for the preparation of 3-methyl-6-nitrophenol.

Abstract: A new selective method for the nitration of m-cresol has been established. 3-Methyl-6-nitrophenol was most efficiently prepared by nitration of 3-methyl-4-sulfophenyl carbonate or phosphate and subsequent hydrolysis and desulfonation. Steric effects on the attacks of sulfonium or nitronium ion to the phosphate are discussed.

Structure Modifications of S-n-Butyl S'-p-tert-Butylbenzyl N-3-Pyridyldithiocarbonimidate (S-1358, Denmert®) and Fungicidal Activities

Abstract: Since S-n-butyl S′-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate, a potent fungicide to powdery mildew, is known to inhibit ergosterol biosynthesis in Monilinia fructigena, the activities were assessed on 24 compounds having other substituents than the 3-pyridyl and on 24 compounds having a variety of different structures connecting the 3-pyridyl and the p-tert-butylphenyl group from that of the dithiocarbonimidate.In the former group the 3-pyridyl group was essential for the activities and the substitution at the 2- or 6-position resulted, on available data, in inactive compounds. Several other β-N-heterocyclic analogs were also active. In the latter group, a number of modified compounds from the dithiocarbonimidate structure were shown to be active.

Structure-activity study of S-1358 and its derivatives. II. Structure modifications of S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate (S-1358, Denmert) and fungicidal activities.

Abstract: Since S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate, a potent fungicide to powdery mildew, is known to inhibit ergosterol biosynthesis in Monilinia fructigena, the activities were assessed on 24 compounds having other substituents than the 3-pyridyl and on 24 compounds having a variety of different structures connecting the 3-pyridyl and the p-tert-butylphenyl group from that of the dithiocarbonimidate. In the former group the 3-pyridyl group was essential for the activities and the substitution at the 2- or 6-position resulted, on available data, in inactive compounds. Several other β-N-heterocyclic analogs were also active. In the latter group, a number of modified compounds from the dithiocarbonimidate structure were shown to be active.

Fungicidal Constituents in “Kuntan” (Calcined Rice Chaff) Smoke

Abstract: Fungicidal constituents against Rhizoctonia solani and Alternalia mali were isolated from Kuntan (calcined rice chaff) smoke. The fungicidal constituents were phenolics (o, m and p-cresol, 4-ethylphenol, 2, 3, 6-trimethylphenol, 4-n-propylphenol, 4-ethyl-2-methoxyphenol, 4-n-propyl-2-methoxyphenol and 4-allyl-2-methoxyphenol) and α, β-unsaturated-γ-butyro-lactones (2-methyl-4-hydroxy-2-hexenoic acid lactone and 2-ethyl-4-hydroxy-2-pentenoic acid lactone). The anti-pathogenic nature of Kuntan may be due in part to the fungicidal constituents isolated from Kuntan smoke.

Structure-activity study of S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate (S-1358, denmert) and its derivatives.

Abstract: Fungicidal activities of S-alkyl S′-p-substituted benzyl N-3-pyridyldithiocarbonimidates toward Coniothyrium diplodiella, Scleotinia sclerotiorum (on agar medium) and Sphaerotheca fuliginea (on pot test) were shown. The activities varied with the change of the S-alkyl group and were maximized at certain numbers of carbon atoms. A different pattern was observed in the activity toward S. fuliginea when the carbon number was 8 or more. Bulkiness of the S-alkyl group also appeared to influence the activities. The steric factor of the p-alkyl substituents mainly influenced the activity toward S. fuliginea up to the tert-butyl analog. The activities toward C. diplodiella and S. sclerotiorum increased with the increase in the bulkiness and the hydrophylicity of the p-substituent. Rm values were determined on reversed phase TLC and the structure-activity correlations were analyzed against hydrophobic (Rm), electronic (σ) and steric (Es) factors on 34 compounds.

Studies on the nitration of m-cresol. a new selective method for the preparation of 3-methyl-6-nitrophenol

Abstract: A new selective method for the nitration of m-cresol has been established. 3-Methyl-6-nitrophenol was most efficiently prepared by nitration of 3-methyl-4-sulfophenyl carbonate or phosphate and subsequent hydrolysis and desulfonation. Steric effects on the attacks of sulfonium or nitronium ion to the phosphate are discussed.