Suzuki, Toshio; Sato, Ohki; Hirama, Masahiro; Yamamoto, Yoshinori; Murata, Michio; Yasumoto, Takeshi; Harada, Nobuyuki Tetrahedron Letters, 1991, vol. 32, # 35 p. 4505 - 4508 doi: 10.1016/0040-4039(91)80025-2