Thienoanellierte 6a?4-Thia-1,6-diazapentalene durch baseninduzierte Dimerisierung von 5-Methyl-isothiazoliumsalzen

Abstract

Thienoanneleted 6aλ4‐Thia‐1,6‐diazapentalenes by Baseinduced Dimerisation of 5‐Methyl‐isothiazolium Salts Isothiazolium salts 2 and 3 are easily available by reaction of (Z/E)‐β‐thiocyanatovinyl aldehydes with primary aliphatic and aromatic amines in acetic acid or with aromatic amine hydrochlorides, respectively. Preparative advantages of this reaction are demonstrated and discussed. Reaction of 3 with secondary amines results in an unexpected formation of 6aλ4‐thia‐1,6‐diazapentalenes 5, a new typ of thiadiazapentalenes anellated with a heterocyclic ring system. The structure of 5 was evidenced by IR, UV, 1H‐, 13C‐n.m.r. spectral data and supported by elemental analysis. By means of 15N‐ and 13C‐n.m.r. spectroscopy the synthesized thiadiazapentalenes were found to be stable towards protonation.

Isothiazoles (1,2-thiazoles): synthesis, properties and applications

“…R 5 224 The reaction between the salts 230 and 235 catalysed by dicyclohexylamine in methanol or DMSO yields `mixed' thiadiazapentalenes 236 upon oxidative cyclisation and salts 237 upon elimination of aniline. 156,157 Photochemical reactions of several isothiazoles have been studied. Irradiation of 4-phenylisothiazole in benzene yielded small amounts of 4-phenylthiazole (238).…”

Synthesis of N,N’-Linked Isothiazolium Salts via Intramolecular Cyclocondensation of Hydrazonium Salts

“…For instance, they are used for transformation of N-nucleophiles (e. g. ammonia) into isothiazoles [1] and of substituted anilines into isothiazolium salts [2].…”