1. O'Brien, P.; Poumellec, P. Tetrahedron Lett. 1996, 37, 8057–8058; O'Brien, P.; Poumellec, P. J. Chem. Soc., Perkin Trans. 1 1998, 2435–2441.
2. Bhuniya, D.; DattaGupta, A.; Singh, V. K. J. Org. Chem. 1996, 61, 6108–6113.
3. For reviews, see: O'Brien, P. J. Chem. Soc., Perkin Trans. 1 1998, 1439–1457; Hodgson, D. M.; Gibbs, A. R.; Lee, G. P. Tetrahedron 1996, 52, 14361–14384.
4. For recent examples, see: Asami, M.; Ogawa, M.; Inoue, S. Tetrahedron Lett. 1999, 40, 1563–1564; Södergen, M. J.; Andersson, P. G. J. Am. Chem. Soc. 1998, 120, 10760–10761.
5. For a preliminary communication of some of this work, see: de Sousa, S. E.; O'Brien, P.; Steffens, H. C. Tetrahedron Lett. 1999, 40, in press.