Acid and base catalyzed intramolecular cyclizations of N-benzoylthiocarbamoyl-acetals.
Acid and base catalyzed intramolecular cyclizations of N-benzoylthioureidoacetal, containing four functional groups adjacent to thiourea such as benzocarbamoyl, acetal, thioure and amide, were investigated. The condensation reaction of N-benzoyl thiocarbamoylglycine amide in the presence of 10% aqueous NaOH provided 1-(2,2-dimethoxy)ethyl-imidazolidine-2-thione exclusively. In the presence of pyridine, it was transformed to 2-thiohydantoin. N-Benzoyl thiocarbamoyl glycine amide was completely transformed to an iminothiazolidine exclusively in the presence of Lewis acid such as borontrifluoride etherate or trimethylsilyl iodide. 1-(2,2-Dimethoxy)ethyl-imidazolidine-2-thione was transformed to imidazole[2,1-b]thiazole and pyrazino[5,1-a]imidazole in the presence of BF3.Et2O and formic acid, respectively.
Lee
B
B
Yuhan Research Center, Kunpo, Kyonggi-Do, Korea. yrcbyl@yuhan.co.kr
Kim
C
C
Lee
J W
JW
D000143:Acids; D000468:Alkalies; D002384:Catalysis; D003500:Cyclization; D007202:Indicators and Reagents; D013859:Thiocarbamates / Q000138:chemical synthesis* / Q000737:chemistry
D000143:Acids; D000468:Alkalies; D007202:Indicators and Reagents; D013859:Thiocarbamates