Titanium tetrachloride-mediated synthesis of N-aryl-substituted azacycles from cyclic ethers

Titanium tetrachloride-mediated transformation of five- and six-membered cyclic ethers to the corresponding N-aryl-substituted azacycles is conducted in moderate to good yields under mild reaction conditions. Computational studies suggested a mechanism involving a Lewis acid-assisted ring-opening, a seven-membered metallacycle intermediate and a ring-closing process facilitated by direct participation of the metal center.