1. F. Bigi, Tetrahedron Lett. 42 (2001) 5203.
2. A. Handan, A. Oznur, K. Ayse, B. Seher, O. Gulten, Indian. J. Chem. 44B (2005) 585.
3. A.K. Raviraj, V.K. Manohar, Indian. J. Chem. 44B (2005) 591.
4. L. Xie, Y. Tukeuchi, L.M. Consetino, K. Lee, J. Med. Chem. 42 (1999) 2662.
5. K.K. Srinivas, E. Hager, C. Pehit, N.E. Davidson, S.R. Khan, J. Med. Chem. 46 (2003) 2813.