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3. J. Wirz,Helv. Chim. Acta.,57, 1283 (1974).
4. J. J. Hurst and G. H. Whitham,J. Chem. Soc., 710 (1963).
5. K. E. Hine and R. F. Childs,J. Am. Chem. Soc.,95, 6116 (1973).