The phenolic methyl ethers of flavan-3-ols, 4/gb-arylflavan-3-ols, and (-)-fisetinidol-(4β,8)-(+)-catechin biflavanoids are susceptible to regio- and stereoselective methoxylation at C-4 in moderate yields with DDQ in CHCl3-MeOH solution. The observed asymmetric induction with exclusive formation of 2,4-trans products is compatible with the intermediacy of a diastereogenic donor-acceptor interaction, DDQ acting as the acceptor and oxidant. The 4-funtionalized analogues are of both synthetic and degradative significance in condensed tannin chemistry. © 1991.
Steenkamp, J. A., Mouton, C. H. L., & Ferreira, D. (1991). Regio- and stereoselective oxidation of flavan-3-ol- 4-arylflavan-3-ol- and biflavanoid derivatives with 2,3-dichloro-56-dicyano-1,4-benzoquinone (DDQ). Tetrahedron, 47(33), 6705–6716. https://doi.org/10.1016/S0040-4020(01)82322-X