Biomimetic synthesis of grandione from demethylsalvicanol via hetero-Diels–Alder type dimerization and structure revision of grandione

Sequential Reactions Initiated by Oxidative Dearomatization. Biomimicry or Artifact?

“…Scheme 20.5 Pettus' oxidative dearomatization and dimerization of 2,6-xylenol with IBX.Although it remains debatable as to whether products of oxidative dimerization actually constitute legitimate natural products or are themselves merely artifacts of isolation, many examples exist in the literature. For instance, Takeya has shown that the o-quinone 22 generated from oxidation of demethylsalvicanol (21) affords grandione(23) when heated in the solid state, through a [4+2] cycloaddition pathway (Scheme 20.6)[13].…”

Semisynthesis of Isetexane Diterpenoid Analogues and Their Cytotoxic Activity

“…4) We confirmed the absolute configuration of 1 to be as reported, by converting 1 to its bis(p-bromobenzoate) (2) and subjecting 2 to X-ray crystallographic analysis, which proved that the absolute configuration of 2 was 5S and 10S (Chart 1). 5,6) Thus, the absolute configuration of 1 was established as 5S and 10S.…”

Recent advances of Diels–Alderases involved in natural product biosynthesis

“…These include intermolecular adducts (plagiospirolide A, obtunone and guaiane sesquiterpene dimer), 7-9 intramolecular adducts (ircinianin, chaetoglobosin A) 10,11 and a hetero-Diels-Alder adducts (grandione). 12 During late 1990s to early 2000s, three DAases, solanapyrone (1) synthase (Sol5: oxidase), 13 lovastatin (2) nonaketide synthase (LovB: polyketide synthase (PKS)) 14 and macrophomate (3) synthase (MPS) 15,16 were reported. The former two enzymes catalyzed intramolecular reactions yielding decalin scaffolds while the latter DAase catalyzed intermolecular reaction.…”