Mechanistic Observations on the Unusual Reactivity of Dioxenone Photosubstrates­ in the Synthesis of Ingenol

Abstract

The irradiation of allylically substituted dioxenone photosubstrates 6 and 21 lead to unexpected products, the formation of which can be explained by a series of transannular hydrogen atom abstractions.

Key Words

photochemistry - natural products - rearrangements - radicals - cycloadditions

References

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• 4 Winkler J. Henegar K. Williard P. J. Am. Chem. Soc.  1987,  109:  2850 
• 5 Winkler J. Shao B. Tetrahedron Lett.  1993,  34:  3355 
• 6 Tan EW. Chan B. Blackman A. J. Am. Chem. Soc.  2002,  124:  2078 

1

Current address: Millennium Pharmaceuticals, Cambridge, MA, USA.

2

Current address: Department of Chemistry, University of Edinburgh, UK.