Synthesis of dl-hedycaryol

Abstract

The synthesis of (M-hedyoaryol (5) according to Scheme I is described. Dimethyl 4-hydroxyisophthalate (1) was hydrogenated over ruthenium dioxide and the resulting dimethyl hydroxycyclohexanedicar boxy late mixture 11 was acetylated. The acetate 12 was pyrolyzed at 260°in the presence of potassium acetate and the major

Relative and Absolute Configuration of Allohedycaryol. Enantiospecific Total Synthesis of Its Enantiomer

“…Because of our interest in biogeneticlike cyclization reactions of germacranes, and because the relative and absolute stereochemistry of allohedycaryol was unsettled, we decided to investigate its enantiospecific synthesis following the strategy outlined in Scheme . The key step in this approach is the conversion of mesylate 4 into allohedycaryol by means of a Marshall fragmentation reaction in which both double bonds are regio- and stereospecifically formed . The synthesis of 4 in turn was planned starting from (+)-α-cyperone ( 5 ) via a number of conversions with the introduction of an equatorial hydroxyl group at C(1) as the most challenging step.…”

The first preparation of enantiopure 1‐methyl‐7‐oxabicyclo[2.2.1]heptan‐2‐one, a versatile chiral building block for terpenoids

“…EXPERIMENTAL 1 H and 13 C NMR spectra were recorded in CDCl 3 containing 0.03% Me 4 Si as internal standard on a Bruker AM400 spectrometer at 400 and 100 MHz, respectively. When necessary, assignments were aided by DEPT-135, 1 H-1 H COSY, and 13 C-1 H COSY experiments.…”

“…1,3 Presently, we have also accomplished an efficient synthesis using (F)-1 of octalone (unpublished results), an important synthetic intermediate for many sesquiterpenoids. 4 Additionally, 1-methyl-7-oxabicyclo[2.2.1]heptan-2-one could be applied to the syntheses of many other bioactive eudesmanes, agarofurans, and monocyclic sesquiterpenes, e.g., norcarotenoids.…”

Hedycaryol – Central Intermediates in Sesquiterpene Biosynthesis, Part II

“…Hedycaryol ( 1 ) is also a proposed intermediate in the biosynthesis of eudesmane‐2α,11‐diol ( 13 ), the product of the sesquiterpene synthase ZmEDS from Zea mays [71] . Herein, the downstream enzymatic cyclisations of 1 are initiated by reprotonation, however, care has to be taken to distinguish enzymatic from non‐enzymatic transformations, as it is well known that 1 can also undergo an efficient non‐enzymatic acid catalysed transannular reaction to yield a mixture mainly composed of α‐, β‐ and γ‐eudesmol ( 14 ‐ 16 , Scheme 4B) [23,72,73] …”

“…[71] Herein, the downstream enzymatic cyclisations of 1 are initiated by reprotonation, however, care has to be taken to distinguish enzymatic from non-enzymatic transformations, as it is well known that 1 can also undergo an efficient non-enzymatic acid catalysed transannular reaction to yield a mixture mainly composed of α-, βand γ-eudesmol (14 -16, Scheme 4B). [23,72,73] Terpene synthases can further convert 1 into eudesmols or guaiols through the protonation induced reactions shown in Scheme 5. Reprotonation of 1 at C1 can lead to I, the precursor to eudesmols, while the alternative reprotonation at C4 results in the secondary cation J that is disfavoured.…”