Ishii, Hideki; Koyama, Hiroko; Hagiwara, Kyoji; Miura, Tomoyuki; Xue, Guangai; Hashimoto, Yoshie; Kitahara, Genta; Aida, Yoko; Suzuki, Masaaki Bioorganic and Medicinal Chemistry Letters, 2012, vol. 22, # 3 p. 1469 - 1474 doi: 10.1016/j.bmcl.2011.06.066