Usuki, Yoshinosuke; Matsumoto, Keiji; Inoue, Takatsugu; Yoshioka, Koichi; Iio, Hideo; Tanaka, Toshio Bioorganic and Medicinal Chemistry Letters, 2006, vol. 16, # 6 p. 1553 - 1556 doi: 10.1016/j.bmcl.2005.12.024