A convenient oxidative cyclodesulfurization method toward the synthesis of benzofused nitrogen heterocycles using inexpensive and readily available potassium periodate as an oxidant was developed. Upon treating isothiocyanates with ortho-substituted anilines bearing N,N-, N,O-, and N,S-bis-nucleophiles, followed by an intramolecular cyclization of the in situ generated monothioureas, substituted 2-aminobenzazole
Benzimidazo[2,1-b]quinazolin-12(6H)ones, immunosuppressives and agents for treatment of auto-immune diseases, are prepared via (1) reacting a 2-chlorobenzimidazole with an anthranilic acid or ester; (2) reacting a 2-aminobenzimidazole with an anthranilic acid or ester in the presence of trifluoroacetic acid or (3) reacting a 2-methylmercaptobenzimidazole with an anthraniloyl halide hydrohalide.