Pryde, David C.; Middleton, Donald S.; Stephenson, Peter T.; Wainwright, Philip; Maddaford, Adrian; Zhang, Xiurong; Leese, David; Glen, Rebecca; Hart, James; Forrest, Neil; Guyot, Thierry Tetrahedron Letters, 2011, vol. 52, # 48 p. 6415 - 6419 doi: 10.1016/j.tetlet.2011.09.074