The Reaction of 2-Methylthio-4, 6-diphenyl-1, 3-thiazin-l-ium Perchlorate with Nucleophiles

Abstract

Several 2-substituted 4, 6-diphenyl-1, 3-thiazin-l-ium salts were accessible conveniently by the reaction of benzoylphenylacetylene with thioamides in the presence of a strong acid. The reactivity of 2-methylthio-4, 6-diphenyl-1, 3-thiazin-l-ium perchlorate (1a) toward nucleophiles, such as active methylenes and various amino compounds, was investigated. Active methylenes and monofunctional primary amines attacked the 2-position of the thiazinium ring to afford 2-(disubstituted methylene)- and 2-(substituted imino)-4, 6-diphenyl-2 H-1, 3thiazines, respectively.
On the o ther hand, bifunctional nucleophiles, such as hydrazine and hydroxylamine, reacted at the 4-and 6-positions of (1a) to give 3, 5-diphenylpyrazole and isoxazole, respectively.