Synthesis of aminoacylated N(6),N(6)-dimethyladenosine solid support for efficient access to hydrolysis-resistant 3'-charged tRNA mimics

RNA-amino acid and RNA-peptide conjugates that mimic charged tRNA 3'-ends are valuable substrates for structural and functional investigations of ribosomal complexes. To obtain such conjugates, most synthetic approaches that are found in the literature make use of puromycin. This well available aminonucleoside antibiotic contains a dimethylamino group at the nucleobase and a methylated tyrosine that is connected via an amide linkage to the ribose moiety. To increase structural diversity, we present the synthesis of a N(6),N(6)-dimethylated 3'-azido-3'-deoxyadenosine precursor that can be coupled to any amino acid. Further derivatization results in the solid support that is eligible for the preparation of stable 3'-aminoacyl- or 3'-peptidyl-tRNA termini with an amide instead of the natural ester linkage. The present work expands our previously established route that delivered a broad range of peptidyl-tRNA mimics to the corresponding counterparts with N(6),N(6)-dimethylation pattern of the terminal adenosine (A76). This aspect is of significance to modulate the binding preferences of the mimics for ribosomal A- versus P-site.