Sadorn, Karoon; Sinananwanich, Warapon; Areephong, Jetsuda; Nerungsi, Chakkrapan; Wongma, Chalayut; Pakawatchai, Chaveng; Thongpanchang, Tienthong Tetrahedron Letters, 2008 , vol. 49, # 29-30 p. 4519 - 4521