A facile synthesis of aryl spirodioxines based on a 3H,3′H-2,2′-Spiro-bi(benzo[b][1,4]dioxine) skeleton

The synthesis of a series of 6,6-bisbenzannulated spiroketals containing a 3H,3'H-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.