Fig. 1: Background for reaction development.

a Representative examples of bioactive N-alkylated purine nucleoside analogues and nucleic acids. b Selected examples of N6-alkylation of purine nucleosides. c Selected examples of late-stage N6 functionalization of purine in DNA/RNA. d Our strategy for late-stage functionalization of N6-alkylated nucleosides, nucleotides, and oligonucleotides with respectively unprotected adenosine. Me methyl, Et ethyl, Ac acetyl, dtbby 4,4’-Di-tert-butyl-2,2’-dipyridyl, Phen o-Phenanthroline, BTMG 2-(tert-butyl)−1,1,3,3-tetramethylguanidine, LED light-emitting diode, MES 2-(N-morpholino) ethanesulfonic acid.