A complete procedure for the chemical synthesis of oligoribonucleotides

The synthesis of a set of protected ribonucleosides bearing a 5'-monomethoxytrityl group and a 2'-t-butyldimethylsilyl group (series 1, MMTNSiOH) and another set having a 2'-t-butyldimethylsilyl and a 3'-levulinyl group (series 3, HONSiLV) is described. These two sets of derivatives along with the dichlorophosphite condensation procedure lead to a rapid and versatile synthetic procedure for the preparation of oligoribonucleotides. Nucleotide chains possessing a methoxytrityl group at the 5'-end and a levulynyl group at the 3'-end possess an easily detected PMR label at each end (a distinct methyl singlet). The synthetic method is illustrated by the synthesis of a hexadecauridylic acid by a block condensation procedure.