3-Deaza-2′-deoxyadenosine: Synthesis via 4-(methylthio)-1H-imidazo[4,5-c]pyridine 2′-deoxyribonucleosides and properties of oligonucleotides

The synthesis of 4-(methylthio)-1H-imidazo[4,5-c]pyridine 2′-deoxy-β-D -ribonucleosides 2 and 9 and the conversion of the N¹-isomer 2 into the 2′,3′-didehydro-2′,3′-dideoxyribonucleoside 3a or (via 7 ) 3-deaza-2′-deoxyadenosine ( 1 ) is described. Phosphonate building blocks of 1 were employed in solid-phase synthesis of self-complementary base-modified oligonucleotides. Their properties were studied with regard to duplex stability and hydrolysis by the restriction enzyme Eco RI.