1997 年 55 巻 8 号 p. 725-733
The thermal reaction of the α, β-unsaturated aldehydes having an 2-alkenylamino moiety at the β-position gave the azepine derivatives in good to excellent yields. When these groups were a part of heterocycles, the azepine derivatives fused by the heterocyclic systems were obtained. The imines of the aldehydes also afforded the azepine derivatives. These azepine-ring formation could be regarded as the intramolecular carbonyl and imine ene reactions classified as a Type III ene reaction. Therein, the reactions proceeded in a highly stereoselective manner. The PM 3 calculations of the model reactions suggest that the azepine-ring formation is constituted of two consecutive orbital-allowed reactions; 1, 6 -hydrogen shift leading to conjugated azomethine ylides and 1, 7-electrocyclization of the azomethine ylides. The scope and limitations of the azepine-ring formation will be discussed.