Kwang, Seob Lee; Seon, Hee Seo; Yong, Ha Lee; Ha, Dong Kim; Moon, Ho Son; Bong, Young Chung; Jae, Yeol Lee; Jin, Changbae; Yong, Sup Lee Bioorganic and Medicinal Chemistry Letters, 2005, vol. 15, # 11 p. 2857 - 2860 doi: 10.1016/j.bmcl.2005.03.095