Routes for the preparation of 2'-silyl protected phosphoramidites of t
he modified nucleosides O-2-methyluridine and O-4-methyluridine are de
scribed. Methodology for the site-specific incorporation of these phos
phoramidites into a 25 nucleotide long oligoribonucleotide sequence by
solid-phase synthesis is reported. (C) 1998 Elsevier Science Ltd. All
rights reserved.