74697-90-8Relevant articles and documents
Studies on Isoxazoles. XI. Pyrolyses of 4-Isoxazolin-3-thiones
Sugai, Soji,Tomita, Kauzo
, p. 103 - 109 (2007/10/02)
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.Keywords- pyrolysis of 4-isoxazolin-3-thiones; thermal ring transformations; 1,4-dithiins; thioacetamides; thiirene intermediates; shielding and deshielding effects; sulfur radicals