1. A. F. Bochkov, V. I. Betaneli, and N. K. Kochetkov, Izv. Akad. Nauk SSSR, Ser. Khim.,1974, 1379.
2. N. K. Kochetkov and A. F. Bochkov, Recent Developments in the Chemistry of Natural Carbon Compounds, Vol. 4, Akademia Kiado, Budapest (1971), p. 79.
3. V. V. Mezedvitskii, E. P. Olekhnovich, and G. N. Dorofeenko, Usp. Khim.,42, 896 (1973).
4. R. H. DeWolfe, Synthesis,3, 153 (1974).
5. B. Helferich and K. Weis, Chem. Ber.,89, 314 (1956).