Studies on Isoxazoles. XI. Pyrolyses of 4-Isoxazolin-3-thiones

Novel pyrolysis reactions of 4-isoxazolin-3-thiones (X) are described, affording two regioisomeric 1, 4-dithiins (III, IV) and thioacetamides (XI). Among the thioacetamides, N-methylbenzoylthioacetamide (XIe) was identical with an authentic sample prepared by the reduction of 2-methyl-5-phenyl-4-iso...

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Bibliographic Details
Published inChemical & pharmaceutical bulletin Vol. 28; no. 1; pp. 103 - 109
Main Authors SUGAI, SOJI, TOMITA, KAZUO
Format Journal Article
LanguageEnglish
Published Tokyo The Pharmaceutical Society of Japan 1980
Japan Science and Technology Agency
Subjects
sulfur radicals
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Summary:Novel pyrolysis reactions of 4-isoxazolin-3-thiones (X) are described, affording two regioisomeric 1, 4-dithiins (III, IV) and thioacetamides (XI). Among the thioacetamides, N-methylbenzoylthioacetamide (XIe) was identical with an authentic sample prepared by the reduction of 2-methyl-5-phenyl-4-isoxazolin-3-thione (Xe) with thiophenol. The structures of the dithiins were deduced from the physicochemical data, especially the shielding and deshielding effects in the NMR spectra. A mechanism for the reactions is proposed by analogy with the thermal isomerization of 3-isoxazolones into 2-oxazolones. In order to account for the formation of the isomeric dithiins, a thiirene intermediate (II) was assumed to be involved in the reaction pathway.
ISSN:0009-2363
1347-5223
DOI:10.1248/cpb.28.103