The synthesis of a series of 6,6-bisbenzannulated spiroketals containing a 3H,3′Η-2,2′-spirobi(benzo[b][1,4]dioxine) ring system is reported. The key step involves addition of a monobenzyl-protected catechol to the epoxide unit of a glycidol bearing a benzyl-protected catechol. The resultant alcohol adduct is oxidized to a ketone that then undergoes hydrogenation and acid-catalyzed cyclization to produce the desired spirodioxines.
