A Pauson-Khand approach to the synthesis of ingenol.
[reaction: see text] Pauson-Khand cyclization of dioxanone photoadduct 21 leads to the formation of a single product in good yield. However, retro-aldol fragmentation of the pentacyclic cyclopentenone 22 leads to the formation of 23, with cis C-8/C-10 intrabridgehead stereochemistry, unlike the target compound ingenol 1, which possesses C-8/C-10 trans intrabridgehead stereochemistry.
Winkler
Jeffrey D
JD
Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA. winkler@sas.upenn.edu
Lee
Esther C Y
EC
Nevels
LaToya I
LI
D003500:Cyclization; D004224:Diterpenes / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism
D004224:Diterpenes; C008125:ingenol