1. N. Rabjohn, in: Organic Reactions, Vol. 24, W. Dauben, ed., Wiley, New York (1976), p. 261.
2. L. J. Altman, L. Ash, and S. Marson, Synthesis, 129 (1974).
3. Y. Masaki, K. Hashimoto, and K. Koji, Tetrahedron Lett., 4539 (1978).
4. K. B. Sharpless, K. M. Gordon, R. F. Lauer, D. W. Patrick, S. P. Singer, and M. W. Young, Chem. Scr.,8A, 9 (1975).
5. Q. N. Porter and J. Baldas, Mass Spectrometery of Heterocyclic Compounds, Wiley-Interscience, New York (1971), p. 225.