Solid-phase synthesis of oligodeoxynucleotides containing 3 '-S-phosphorothiolate linkages

For the first time a fully automated procedure has been developed for the i ncorporation of a 3'-S-phosphorothiolate linkage into DNA, using phosphorot hioamidite monomers. Coupling yields with either of the activators 5-ethylt hiotetrazole or 4,5-dicyanoimidazole were in the range of 80-90%. Coupling yields were equally good when performed on either a 0.2 or 1 mu mole reacti on column, thus facilitating large scale synthesis.