Synthesis of 3-phenyl- and 3-phenyl-1-methylimidazo [5, 1-b] benzoxazoles

Reduction of 2-benzoylbenzoxazole oxime gives 2-(-aminobenzyl) benzoxazole, converted to the formyl or acetyl derivative by treatment with, respectively, ethyl formate or acetic anhydride. Thiourea derivatives are obtained by treating 2-(-aminobenzyl) benzoxazole with arylisothiocyanates. Heating the above formyl or acetyl derivative with phosphorus oxychloride converts them to 3-phenyl- and 3-phenyl-1-methylimidazo [5, 1-b]-benzoxazole, which are representative members of a new tricyclic system. It did not prove possible to cyclize 1-[-(benzoxazolyl-2) benzyl]-3-phenylthiourea.