The synthesis of oligodeoxynucleotides is marred by several problems that contribute to the formation of defective molecules. This in turn seriously limits the usefulness of such reagents in DNA diagnostics, molecular cloning, DNA structural analysis and in antisense therapy. In particular, depurination reactions during the cyclical steps of synthesis lead to strand scission during cleavage of the completed molecules from the support. Here we present a remedy to this problem: a novel disiloxyl linkage that connects oligonucleotides to the support withstands reaction conditions that allow the removal of the 5' parts of any depurinated molecules. This ensures that all molecules that preserve the 5' protecting group when cleaved from the support will have both correct 3'- and 5'-ends. We demonstrate the application of the support for synthesis of padlock probe molecules.