1. V. P. Borovik, V. F. Sedova, and O. P. Shkurko, Khim. Geterotsikl. Soedin., No. 11, 1534 (1993).
2. A. R. Katritzky and C. W. Rees (eds.), Comprehensive Heterocyclic Chemistry, Vol. 6, Pergamon, Oxford (1994), p. 120.
3. R. K. Smalley, Adv. Heterocycl. Chem.,29, 43 (1981).
4. K. Ataka and M. Watanabe, Jpn. Kokai Tokkyo Kohu 85.252.472; Chem. Abstr.,104, 207253 (1986).
5. K. A. Kim, S. Y. Park, N. Kim, S. H. Hong, and H. Sasabe, J. Appl. Polym. Sci.,46, 1 (1992); Chem. Abstr.,117, 172204 (1992).