Glucose-derived 3 '-(carboxymethyl)-3 '-deoxyribonucleosides and 2 ',3 '-lactones as synthetic precursors for amide-linked oligonucleotide analogues

Treatment of a 1,2-O-isopropylidene-3-ketopentofuranose derivative (obtaine d from D-glucose) with [(ethoxycarbonyl)methylene]triphenylphosphorane and catalytic hydrogenation of the resulting alkene gave stereodefined access t o 3-(carboxymethyl)-3-deoxy-D-ribofuranose derivatives. Esters of 5-O-acety l- or 5-azido-5-deoxy-3-(carboxymethyl)-D-ribofuranose were coupled with nu cleobases to give branched-chain nucleoside derivatives. Ester saponificati on and protecting group manipulation provided 2'-O-(tert-butyldimethylsilyl ) ethers of 5'-azido-5'-deoxy- or 5'-O-(dimethoxytrityl) derivatives of 3'- (carboxymethyl)-3'-deoxyribonucleosides that are effective precursors for s ynthesis of amide-linked oligoribonucleosides.