Okamura, Hiroaki; Kuroda, Satoru; Tomita, Kenji; Ikegami, Satoru; Sugimoto, Yu-ichi; et al. Tetrahedron Letters, 1991, vol. 32, # 38 p. 5137 - 5140 doi: 10.1016/S0040-4039(00)93448-8