Tetraethylene Glycol-Derived Spacer for Oligonucleotide Synthesis   3,6,9-Trioxaundecane-1,11-diisocyanate was synthesised from tetraethylene glycol in 5 steps and 48 % overall yield. The spacer was monofunctionalised with a fully protected adenosyl-3'-O-succinate derivative and linked to aminomethyl polystyrene (50 % crosslinked with divinylbenzene) affording a solid support suitable for oligoribonucleotide synthesis (loading: ~20 µmol/g). The HPLC analysis of a crude oligoribonucleotide synthesis and the isolated yield of purified oligomer show that this spacer compares well to the commercially used hexamethylene diamine.