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

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) .