Studies on synthesis and structure of O-beta-D-ribofuranosyl(1"-->2')ribonucleosides and oligonucleotides.

Minor nucleosides found in several eukaryotic initiator tRNASiMet, O-beta-D-ribofuranosyl(1"-->2')adenosine and -guanosine (Ar and Gr), as well as their pyrimidine analogues, were obtained from N-protected 3',5'-O-(1,1,3,3-tetraisopropyldisiloxane-1,3-diyl)ribonucle osides and 1-O-acetyl-2,3,5-tri-O-benzoyl-beta-D-ribofuranose in the presence of tin tetrachloride in 1,2-dichloroethane. A crystal structure has been solved for 2'-O-ribosyluridine. The 3'-phosphoramidites of protected 2'-O-ribosylribonucleosides were prepared as the reagents for 2'-O-ribofuranosyloligonucleotides synthesis. O-beta-D-Ribofuranosyl(1"-->2')adenylyl(3'-->5')guanosine (ArpG) was obtained and its structure was analysed by NMR spectroscopy.