The introduction of the p-nitrophenylethyl- (NPE) and p-nitrophenyleth
oxycarbonyl- (NPEOC) group for amino and hydroxy protection of purine
and pyrimidine arabinofuranosides and their interconversion into the c
orresponding 3'-phosphoramidite building blocks provided very effectiv
e starting materials for solid support oligoarabinonucleotide synthese
s. A structural analogue of the Phage T5 histidine tRNA consisting of
78 nucleotide units has been synthesized in excellent yield and high p
urity.