S. Takamura et al., Preparation of 2,5-iminoazepines via the imine-ene reaction of 3-allylamino-2-(substituted)acrolein imines, J CHEM R-S, (9), 2000, pp. 426-428
Malonaldehyde derivatives 1 and 2 with an excess of allylamine (3a) in refl
uxing toluene gave 2,5-iminoazepines 6a and 9a in moderate yields via the t
hermal imine-ene reaction of the initially formed vinamidines 5a and 8a.