Synthesis of novel 3-oxa-chromanol type antioxidants

Condensation of trimethylhydroquinone with aldehydes provides 2,4-disubstituted 5,7,8-trimethyl-4H-benzo[1,3]dioxin-6-ols in a straightforward one-pot reaction. These compounds are 3-oxa-derivatives of α-tocopherol (vitamin E) and represent an interesting novel class of phenolic antioxidants. The formation reaction proceeds according to a two-step mechanism consisting of electrophilic substitution and acetalization, and provides the product as a cis/trans-mixture of diastereomers.