Kaulen, Johannes; Schaefer, Hans-J.
Tetrahedron, 1982 , vol. 38, # 22 p. 3299 - 3308

Harayama, Takashi; Shinkai, Yutaka; Hashimoto, Yukiya; Fukushi, Hideto; Inubushi, Yasuo
Tetrahedron Letters, 1983 , vol. 24, # 47 p. 5241 - 5244