Hydroxyl-Functionalized DNA: An Efficient Orthogonal Protecting Strategy and Duplex Stability

Tert-butyldiphenylsilyl (TBDPS) was found to be an effective orthogonal protecting strategy for the 5-substituted hydroxyl groups of de novo synthesized deoxyuridine analogues 1-3 and 7-(3-hydroxypropynyl)- of 8-aza-7-deazadeoxyadenosine 4 for their incorporation into oligodeoxynucleotides by phosphoramidite chemistry. It could be completely cleaved under normal and ultra-mild deprotection conditions applied to DNA synthesis, without extra cleaving operation. The new phosphoramidites were coupled as usual with high yields. The new modified oligodeoxynucleotides were characterized by MALDI-TOF and enzymatic cleavage analysis. The thermal stability and conformation of these hydroxyl-functionalized DNA duplexes were evaluated.