Intramolecular heterocyclization of o-(1-cycloalkenyl)anilines 2*. Synthesis of new 4Н-3,1-benzoxazine and 4Н-3,1-benzothiazine 2-amino derivatives

A new method was developed to synthesize 2-amino derivatives of 3,1-benzoxazines and 3,1-benzothiazines on the basis of о-(cyclopent-1-en-1-yl)aniline by heterocyclization of phenyl- and allylurea and thiourea derivatives in the presence of CF3CO2H, H2O2, or Br2.