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 .

1 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).