Iodine-promoted synthesis of CF 3 -substituted dihydroimidazobenzimidazole and CF 3 -dihydroimidazoindole via C-N bond formation.

The iodine-promoted cyclization of various N -(2-CF 3 -2-NHTs)ethylbenzimidazoles and N -(2-CF 3 -2-NHTs)ethylindoles proceeded smoothly and efficiently under mild basic conditions. This reaction did not require transition metals and afforded the corresponding CF 3 -dihydroimidazobenzimidazoles and CF 3 -dihydroimidazoindoles in 85-93% and 42-82% yields, respectively.