text: The first total synthesis of carpanone was the biomimetic approach published by Chapman et al. in 1971. The required desmethylcarpacin (2-allylsesamol), shown below as the starting molecule in the scheme, is acquired in two high-yield steps involving three transformations: 
  * allylation of the phenolic anion generated after treatment of sesamol with potassium carbonate and allyl bromide,
  * followed by a thermal Claisen rearrangement to move the O-allyl group onto the adjacent site on the aromatic ring, and then 
  * thermal isomerization of the Claisen product, to move the terminal olefin (alkene) into conjugation with the ring (with e.g., potassium tert-butoxide as base).
  This procedure is one of several that gives the required desmethylcarpacin (carpacin with the methyl of its methoxy group removed). Though oxidative dimerizations of phenols normally used a 1-electron oxidant, Chapman then followed a precedent involving a 2-electron oxidant and treated desmethylcarpacin with PdCl in the presence of sodium acetate (e.g., dissolved in a mixture of methanol and water); the reaction was perceived to proceed via a complexation of a pair of carpacins to the Pd(II) metal via their phenolic anions (as shown in scheme, below right), followed by a classic 8-8 (β-β) oxidative phenolic coupling of the two olefin tails—shown crossing in the image—to give a dimeric trans-ortho-quinone methide-type of lignan intermediate. A particular conformation of this dimer then places a 4-electron enone of one ring over the 2-electron enol of the other (shown adjacent in image for clarity), setting the state for a variant of the Diels-Alder reaction termed an inverse demand Diels-Alder reaction (see curved arrows in image), which closes the 2 new rings and generates the 5 contiguous stereocenters. The carpanone is produced in yields of ≈50% by the original method, and in yields >90% in modern variants (see below). The synthesis of a single diastereomer was confirmed in the original Chapman work, using X-ray crystallography.
  For the elegance of its "one-pot construction of a tetracyclic scaffold with complete stereocontrol of five contiguous stereo centers", the original Chapman design and synthesis is "[n]ow considered a classic in total synthesis" that "highlights the power of biomimetic synthesis".