The Diels-Alder reaction of maldoxin with an isopropenylallene at 60-75 °C afforded an adduct closely related to chloropestolide A (24%) and a second adduct (0-11%) that underwent an ene reaction to generate the chloropupukeanolide D (11-22%) skeleton. The Diels-Alder reaction occurred with good selectively (>5:1) from a single face of maldoxin under much milder conditions than previously reported for the analogous dimethoxycyclohexadienone. Furthermore, the ene reaction took place under mild conditions whereas the analogous Diels-Alder adduct from the dimethoxycyclohexadienone did not undergo an ene reaction.
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| http://dx.doi.org/10.1016/j.tet.2011.09.117 | DOI Listing |
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