Pawhuskin A is a prenylated stilbene that functions as an antagonist of the kappa opioid receptor. Analogues of this natural product bearing different placements of the prenyl group in the A-ring have shown selectivity for either the kappa or the delta receptors subtypes. This differential activity has drawn attention to regiospecific preparation of the C-2, C-5, and C-6 prenylated A-ring regioisomers. Through halogen metal exchange, advanced intermediates representing each of these regioisomers have been prepared, and the new C-6 intermediate has been converted to a new analogue of the natural stilbene.

The structure of a trinuclear zinc complex, hexakis(μ2-2-anilinobenzoato)diaquatrizinc(II), [Zn2(C13H10NO2)6(H2O)2] or (NPA)6Zn3(H2O)2 (NPA is 2-anilinobenzoate or N-phenylanthranilate), is reported. The complex crystallizes in the triclinic space group P\overline{1} and the central ZnII atom is located on an inversion center. The NPA ligand is found to coordinate via the carboxylate O atoms with unique C—O bond lengths that support an unequal distribution of resonance over the carboxylate fragment. The axial H2O ligands form hydrogen bonds with neighboring molecules that stabilize the supramolecular system in rigid straight chains, with an angle of 180° along the c axis. π stacking is the primary stabilization along the a and b axes, resulting in a highly ordered supramolecular structure. Docking studies show that this unique supramolecular structure of a trinuclear zinc complex has potential for binding to the main protease (Mpro) in SARS-CoV-2 in a different location from Remdesivir, but with a similar binding strength.

To gain access to prenylated hexahydroxanthenes, tandem cascade cyclization-electrophilic aromatic substitution reactions have been studied on substrates bearing allylic and propargylic substituents. Both BF3·OEt2 and TMSOTf can be used to initiate this reaction sequence, resulting in different ratios of the C-2 and C-6 substitution products. Even though allylic transposition is observed in some cases, the results of a crossover experiment are consistent with an intramolecular reaction sequence. Taken together, these studies now allow preparation of either the C-2 or C-6 prenylated hexahydroxanthene products.