Mutou, Tsuyoshi; Kondo, Takashi; Shibata, Takunobu; Ojika, Makoto; Kigoshi, Hideo; Yamada, Kiyoyuki Tetrahedron Letters, 1996, vol. 37, # 40 p. 7299 - 7302 doi: 10.1016/0040-4039(96)01653-X