1. For earlier syntheses see;Gates;Am Chem Soc,1952
2. Unpublished Observations ITSUU Lab;Barton;Pharm Soc Japan,1961
3. seealso in press;Battersby;Proc Chem Soc Chem Soc,1963
4. Unpublished observations;Robinson;Chem Soc Naturwiss Ann Chem Soc Tetrahedron Letters,1931
5. See;Corrodi;Helv Chim Acta,1956