1. V. I. Minkin and R. M. Minyaev, Zh. Org. Khim.,13, 1129 (1977).
2. R. M. Minyaev, V. I. Minkin, and M. E. Kletskii, Zh. Org. Khim.,14, 449 (1978).
3. I. Ugi and F. Ramirez, Chem. Brit.,8, 100 (1972).
4. R. Hoffmann, J. M. Howell, and E. L. Muetterties, J. Am. Chem. Soc.,94, 3047 (1972).
5. V. I. Minkin and R. M. Minyaev, Zh. Org. Khim.,11, 1993 (1975).