Studies on the synthesis of oligonucleotides containing photoreactive nucleosides: 2-azido-2'-deoxyinosine and 8-azido-2'-deoxyadenosine.

Oligonucleotides containing the photoreactive nucleosides 2-azido-2'-deoxyinosine and 8-azido-2'-deoxyadenosine have been prepared using protected 2-fluoro-2'-deoxyinosine and 8-bromo-2'-deoxyadenosine phosphoramidites. After the assembly of the oligonucleotides, the nucleoside derivatives are converted to the corresponding azido derivatives by treatment with lithium azide in dry DMF. Deprotection of oligonucleotides carrying these azidonucleosides is performed with concentrated ammonia at room temperature.