1. Giannis, A.; Kolter, T. Angew. Chem. Int. Ed. Engl. 1993, 32, 1244; Kahn, M. Synlett 1993, 821.
2. For reviews see Alami, A.; Calmes, M.; Daunis, J.; Jacquier, R. Bull. Soc. Chim. Fr. 1993, 130, 5; Burgess, K.; Ho, K. K.; Moye-Sherman, D. Synlett 1994, 575.
3. Stammer, C. H. Tetrahedron 1990, 46, 2231.
4. Fowden, L.; Smith, A.; Millington, D. S.; Sheppard, R. C. Phytochemistry 1969, 8, 437.
5. Kurokawa, N.; Ohfune, Y. Tetrahedron Lett. 1985, 26, 83; Yamanoi, K.; Ohfune, Y. Tetrahedron Lett. 1988, 29, 1181.