Claisen self-condensation/decarboxylation as the key steps in the synthesis of C2-symmetrical 1,7-dioxaspiro[5.5]undecanes

A convenient method for the synthesis of functionalised 1,7-dioxaspiro[5.5]undecanes using acid-catalysed spiroketalisations of substituted dihydroxyketones is described. The dihydroxyketones were readily prepared from appropriately substituted hydroxy esters via Claisen self-condensation followed by decarboxylation.