The synthesis of the SoA linker phosphoramidite 1f is shown in Scheme 4. The SoB derivative 15 was easily prepared from compound 13. Reaction of 15 with 16 using DIC as the activator gave 17. The benzyl group was then removed under catalytic hydrogenation conditions using ammonium formate as the hydrogen source and palladium on carbon as the catalyst. The DMTr protection was found stable under the conditions. Phosphitylation of 18 under standard conditions gave the target SoA linker phosphoramidite 1f in acceptable yield.