[3, 3]-Sigmatropic rearrangement of N-trifluoroacetyl enehydrazines provides a novel method for the construction of indoles. N-Trifluoroacetyl enehydrazine having a cyclopentene ring smoothly underwent [3, 3]-sigmatropic rearrangement followed by cyclization to give indolines in excellent yield. On the other hand, both cyclohexenyl N- trifluoroacetyl enehydrazine and acyclic N-trifluoroacetyl enehydrazine gave indoles in ...