1. M. Ohashi, J. A. Joule, B. Gilbert, andC. Djerassi, Exper.20, 263 (1964).
2. J. Schmutz, F. Hunziker, andR. Hirt, Helv. chim. Acta40, 1189 (1957).
3. G. Büchi andE. W. Warnhoff, J. Am. chem. Soc.81, 4433 (1959).
4. H. Budzikiewicz, C. Djerassi, andD. H. Williams,Structure Elucidation of Natural Products by Mass Spectrometry, vol. I,Alkaloids (Holden-Day, Inc., San Francisco 1964).
5. B. Gilbert, L. D. Antonaccio, A. A. P. G. Archer, andC. Djerassi, Exper.16, 61 (1960).