We report high yield procedures for protection of purine ribonucleosides ba
sed on a reaction which allows concomitant highly regiospecific 2'-silylati
on and 3'-phosphitylation. Subsequent cleavage of the H-phosphonate monoest
er moiety without silyl migration provides intermediates ready for phosphit
ylation by standard methods to give fully protected phosphoramidites. (C) 1
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