Malonaldehyde derivatives 1 and 2 with an excess of allylamine (3a) in refluxing toluene gave 2,5-iminoazepines 6a and 9a in moderate yields via the thermal imine–ene reaction of the initially formed vinamidines 5a and 8a.
References
1.
For a review on vinamidines, see: LloydD., McNabH., Angew. Chem. Int. Ed. Engl., 1976, 15, 459.
This compound can be purchased from Ube Industries LTD.
5.
Crystallographic data for the structure of cycloadduct 6a have been deposited with the Cambridge Crystallographic Data Centre no. 146327. 12 Union Road, Cambridge CB2 1EZ, UK.
6.
BüchiG., CarlsonJ. A., PowellJ. E., TietzeL. F., J. Am. Chem Soc., 1973, 95, 540.
7.
NoguchiM., YamadaH., TakamuraS., OkadaK., KakehiA., YamamotoH., Tetrahedron, 2000, 56, 1299; M. Noguchi, H. Yamada, S. Takamura, T. Uchida, M. Hironaka, A. Kakehi, H. Yamamoto, Eur. J. Org. Chem., 2000, 1489. Also, see references cited therein.
8.
Description of usual instruments, general procedures, and chromatographic procedures have been reported.7
