Novel Parallel Reaction between a [1,5] Sigmatropic Alkylthio Shift and a [1,5] Sigmatropic Hydrogen Shift Observed in a 2<i>H</i>-Azepine Ring

Although heating 2-methoxy-2<i>H</i>-azepine results in a [1,5] sigmatropic hydrogen shift, heating 2-propylthio-2<i>H</i>-azepine results in not only a [1,5] sigmatropic hydrogen shift but also a [1,5] sigmatropic propylthio shift. Kinetic measurements reveal that migratory aptitudes increase in the order of MeO < H, PrS. These [1,5] sigmatropic shifts are discussed on the basis of ab initio DFT calculations.