Synthesis of methyl 2-O-allyl-(and 3-O-allyl-) 5-O-benzyl-β-d-ribofuranoside

Abstract d -Ribose was converted into methyl 5-O- benzyl -β- d -ribofuranoside and this, on tin-mediated allylation, gave a mixture of the 2- O -allyl and 3- O -allyl derivatives which were separated by chromatography. The more polar isomer was characterised as the 3- O -allyl derivative after conversion via 3-O- allyl -5-O- benzyl -1,2-O- isopropylidene -α- d -ribofuranose (which was also synthesised from 3-O- allyl -1,2:5,6- di -O- isopropylidene -α- d -allofuranose ) into the known 5-O- benzyl -1,2-O- isopropylidene-α- d -ribofuranose . Methyl 3-O- allyl -5-O- benzyl-β- d -ribofuranoside was converted into methyl 2-O- allyl -5-O- benzyl-β- d -ribofuranoside via methyl 2-O- allyl -5-O- benzyl -3-O- (prop-1-enyl)-β- d -ribofuranoside .