Xu, Tinghua; Lu, Ran; Jin, Ming; Qiu, Xianping; Xue, Pengchong; Bao, Chunyan; Zhao, Yingying Tetrahedron Letters, 2005, vol. 46, # 40 p. 6883 - 6886 doi: 10.1016/j.tetlet.2005.08.012