8-aza-7-deazaadenine and 7-deazaguanine: Synthesis and properties of nucleosides and oligonucleotides with nucleobases linked at position-8

Abstract

The 8-aza-7-deazaadenine (pyrazolo[3,4-d]pyrimidin-4-amine) N-8-(2'-deoxyribonucleoside) (2) and the 7-deazaguanine (pyrrolo[3,4-d]pyrimidine-2-amin-(3H)-4-one) C-8-(2'-deoxyribonucleoside) (4) were synthesized and incorporated in oligonucleotides employing phosphoramidite chemistry. Oligonucleotides carrying compound 2 are able to form base pairs with the four canonical DNA constituents without significant structural discrimination. The nucleoside 4 was obtained from the corresponding ribonucleoside by deoxygenation. Oligonucleotides containing compound 4 showed similar base pairing properties as those with 2'-deoxyisoguanosine.