1. D. Enders, O. Meyer and G. Raabe,Synthesis, 1992, 1242; D. Enders, O. Meyer, G. Raabe, and J. Runsink,Synthesis, 1994, 66.
2. J. Barluenga, F. Aznar, C. Valdés, and J. A. Martin,Anal. de Quim., 1993,89, 115; J. Barluenga, F. Aznar, C. Valdés, J. A. Martin, S. Garcia-Grandez, and E. Martin,J. Am. Chem. Soc., 1993,115, 4403.
3. A. G. Nigmatov and E. P. Serebryakov,Izv. Akad. Nauk, Ser. Khim., 1993, 233 [Russ. Chem. Bull., 1993,42, 213 (Engl. Transl.)].
4. A. G. Nigmatov, I. N. Kornilova, and E. P. Serebryakov,Izv. Akad. Nauk, Ser. Khim., 1996, 154 [Russ. Chem. Bull., 1996,45, 144 (Engl. Transl.)].
5. A. G. Nigmatov and E. P. Serebryakov,Izv. Akad. Nauk, Ser. Khim., 1996, 663 [Russ. Chem. Bull., 1996,45, 623 (Engl. Transl.)].