2′‐Hydroxyl‐Protecting Groups that are Either Photochemically Labile or Sensitive to Fluoride Ions

Protected ribonucleotide monomers are more difficult to obtain than their 2′‐deoxy counterparts because of the need to protect the 2′‐hydroxy function. This unit describes the stepwise preparation of suitably 2′‐protected ribonucleosides using two protecting groups: 2‐nitrobenzyloxymethyl (NBOM) and tert‐butyldimethylsilyl (TBDMS). In addition, details are given for protecting the 5′‐hydroxyl and the nucleobase, yielding nucleosides that are easily converted to phosphoramidite or H‐phosphonate derivatives for automated oligoribonucleotide synthesis.