Etude dans la série des radicaux hétérocycliques. Partie XV. Décomposition aprotique de l'amino-6-éthyl-2-benzothiazole dans des substrats aromatiques et hétéroaromatiques: préparation des mésityl-6- et furyl-6-éthyl-2-benzothiazoles, des sels quaternaires et des spiropyrannes correspondants

✍ Scribed by Gaston Vernin; Jacky Kister; Jacques Metzger

• Publisher: John Wiley and Sons
• Year: 1979
• Tongue: German
• Weight: 610 KB
• Volume: 62
• Category: Article
• ISSN: 0018-019X
• DOI: 10.1002/hlca.19790620104

✦ Synopsis

Abstract

Study of heteroaromatic radicals. Part XV. Partie XIV: cf. [1].

Aprotic decomposition of 6‐amino‐2‐ethylbenzothiazole in aromatic and heteroaromatic substrates: preparation of 6‐mesityl‐ and 6‐furyl‐2‐ethylbenzothiazoles and of the corresponding quaternary salts and spyropyrans

In the presence of excess isopentyl nitrite in aprotic solvent, the 6‐amino‐2‐ethyl‐benzothiazole leads to 6‐aryl‐ and 6‐heteroaryl‐2‐ethylbenzothiazoles 1 to 14 in ca. 20–50% yield (Scheme 1, Table 1). The 2‐ethyl‐6‐benzothiazolyl radicals generated during these reactions exhibit a weak electrophilic character (Table 2).

Preparatively this method has been applied to the synthesis of 6‐mesityl‐ and 6‐furyl‐2‐ethylbenzothiazoles 6 and 7, which were used to prepare the corresponding quaternary salts 15, 16 and the spiropyrans 19, 20 (Scheme 4).