1. For reviews of the Daphniphyllum alkaloids, see: (a) Yamamura, S.; Hirata, Y. In The Alkaloids; Manske, R. H. F., Ed.; Academic Press: New York, 1975; Vol. 15, p 41. (b) Yamamura, S. In The Alkaloids; Brossi, A., Ed.; Academic Press: New York, 1986; Vol. 29, p 265.
2. Morita, H., Yoshida, N., Kobayashi, J. J. Org. Chem. 1999, 64, 7208–7212; Morita, H.; Yoshida, N.; Kobayashi, J. Tetrahedron 1999, 55, 12549–12556.
3. Niwa, H.; Toda, M.; Hirata, Y.; Yamamura, S. Tetrahedron Lett. 1972, 2697–2700; Toda, M.; Niwa, H.; Irikawa, H.; Hirata, Y.; Yamamura, S. Tetrahedron 1974, 30, 2683–2688; Sasaki, K.; Hirata, Y. Tetrahedron Lett. 1972, 1891–1894. 13C NMR assignments of daphnilactone B (5) were carried out on the basis of 2D NMR experiments (see Experimental), since there were no reports on it.
4. Sakurai, H.; Sakabe, N.; Hirata, Y. Tetrahedron Lett. 1966, 6309–6314; Irikawa, H.; Yamamura, S.; Hirata, Y. Tetrahedron 1972, 28, 3727–3738.
5. Kobrich, G. Angew. Chem., Int. Ed. Engl. 1973, 12, 464–473 and references cited therein. Anti-Bredt-rule imine of secodaphniphylline-type skeleton has already been derived from methyl homosecodaphniphyllate, Toda, M.; Hirata, Y.; Yamamura, S. J. Chem. Soc., Chem. Commun. 1970, 1597–1598.