Cunningham CW, Hom K, Acharya C, Wilks A, MacKerell AD, Coop A. Synthesis and Characterization of a Novel Diels - Alder Adduct of Codeine.
Helv Chim Acta 2010;
93:220-226. [PMID:
23378668 PMCID:
PMC3562130 DOI:
10.1002/hlca.200900234]
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Abstract
The Diels - Alder reaction was applied to 4,5-epoxymorphinan opioids to generate a novel aromatic cycloadduct at C(7) - C(8): Thermolytic cleavage of sultine 8 produced the reactive diene o-quinodimethane 7 which condensed favorably with codeine (11), but not with codeinone (9) or 14- hydroxycodeinone (10), producing the desired tetrahydronaphtho adduct 12 with (7R,8R) geometry (Scheme). The configuration of the cycloadduct was determined by 1D- and 2D-NMR experiments. The unanticipated reactivity of these codeine derivatives was investigated by quantum-mechanical calculations, and it was determined that steric effects of the 6-keto and 14-hydroxy group likely precluded condensation by raising the molecular energy of their respective transition states.
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