A Diels-Alder Approach to Benzannulated [5,6]-Spiroketals

Significance

Reported is the synthesis of arylsubstituted benzannulated [5,6]-spiroketals from the thermal reaction of 2-hydroxybenzylacetates with γ-methylene-γ-butyrolactone. The reaction proceeds via an ortho-quinone methide which then undergoes Diels-Alder cycloaddition to give the spiroketal products. The starting acetates were synthesized in high yield through selective acetylation of the requisite 2-hydroxybenzyl alcohols.