Synthesis of 2,2-functionalized benzo[1,3]dioxoles

Highly functionalized catechol ketals exhibiting either a tert-butyl moiety or a spiro center in position 2 are synthesized by ketalization and functionalized in a sequence of subsequent transformations. By a specific ketalization protocol catechol ketals of enolizable beta-keto esters can be prepared. With the succeeding steps these compounds incorporate moieties, which are not compatible and accessible by direct ketalization of catechol. (C) 2009 Elsevier Ltd. All rights reserved.