Abstract
Formation and some electrophilic reactions of 2-imino-2H-cycloheptoxazole derivatives were described. Reaction of 2-methoxytropone (I) with O-ethylisourea or cyanamide in the presence of sodium ethoxide gave the sodium salt of 2-cyanaminotropone (III). Neutralization of III resulted in the cyclization to its ring-tautomer, 2-imino-2H-cycloheptoxazole. The sodium salts (VII-XIII) listed in Table I were obtained by the reaction of substituted 2-methoxytropones with sodium salt of cyanamide. 8-Isopropyl-(XIV), 6-chloro-(XV), and 8-chloro-2-imino-2H-cycloheptoxazole (XVI) were prepared by the neutralization of the sodium salts (XIII, VII, and VIII), and their ring-chain tautomerisms were discussed. The reaction of V with benzoyl, p-toluensulfonyl, and tropylium chloride in the presence of triethylamine gave 2-benzoyl-(XXV), 2-(p-toluensulfonyl) imino-(XXVIII), and 2-tropylimino-2H-cycloheptoxazole (XXX), respectively. heptoxazole (XXIX). Heating of XXV in ethanol solution gave N-benzoylcarbamoyl-2-ethoxytroponeimine (XXVII). While the treatment of XXV with anhydrous hydrogen chloride gave its hydrochloride (XXVI), the similar acid treatment of XXX resulted in its decomposition to VI and a tropylium cation.
