Oxidative dimerization of methyl (E)-sinapate

Abstract

Oxidation of methyl (E)-sinapate (1c) with 1 equiv. of ferric chloride in aqueous acetone gave the tetralols (2a) and (2b), the dihydronaphthol(3a), and the lactone (4), all of which result from C-C coupling, and an unidentified oil. The configurations of tetralols (2a) and (2b) were ascertained by their conversion into (±)-lyoniresinol dimethyl ether (5c) of known stereochemistry, and by p.m.r, spectroscopy. The dimethyl ether (3b) of compound (3a) was identified as thomasidioic acid dimethyl ether dimethyl ester. Reaction of phenol (1c) with other one-electron oxidants is briefly discussed.