3
DCC-mediated coupling reaction of dioxinone acid 9
meroterpenoids and related medicinal chemistry are ongoing in
our laboratory.
with malonate 10 (R = H) was determined by 1H NMR
spectroscopy with the use of pentachloroethane as
internal standard. It was observed that dioxane-4,6-
dione-keto-dioxinone 11 decomposed slowly to
dioxinone-acyl ketene at 25 oC and reacted with
moisture to form β-keto-dioxinone. Storage of dioxane-
4,6-dione-keto-dioxinone 11 is possible at -20 oC for 24
h.
Acknowledgments
We thank GlaxoSmithKline for the endowment (to A.G.M.B).
Supplementary data
Supplementary data associated with this article can be found,
in the online version, at xxx.
13. a arro rl i , C.; Schlingmann, G.; Barrett, A.
G. M. J. Org. Chem. 2009, 74 (21), 8139–8142.
14. Gassman, P. G.; Schenk, W. N. J. Org. Chem. 1977, 42
(5), 918–920.
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11. Dioxinone β,δ-diketo esters exist as mixtures of keto-
enol tautomers. They have been drawn as the keto-
tautomer throughout the article for simplicity.
12. Dioxane-4,6-dione-keto-dioxinone 11 could not be
purified by column chromatography, the yield of the