Efficient and Improved Solution-Phase Synthesis of Modified RNA Dinucleotides: Versatile Synthons in Cap 1 mRNA Therapeutics

Efficient chemical synthesis of N2-modified guanosine derivatives: a versatile probes for mRNA labeling

An efficient method for the synthesis of N2-modified guanosine nucleotides such as N2-[benzyl-N-(propyl)carbamate]-guanosine-5'-O-monophosphate, N2-[benzyl-N-(propyl)carbamate]-guanosine-5'-O-diphosphate, N2-[benzyl-N-(propyl)carbamate]-guanosine-5'-O-triphosphate, and N2-[benzyl-N-(propyl)carbamate]-N7-methyl-guanosine-5'-O-diphosphate, starting from the corresponding nucleotide is described. The overall reaction involves the condensation between the exocyclic amine of guanosine nucleotide with 3-[(benzyloxycarbonyl)amino]propionaldehyde in aqueous methanol, followed by reduction using sodium cyanoborohydride to furnish the corresponding N2-modified guanosine nucleotide in moderate yield with high purity (>99.5%).

Click-iT trinucleotide cap analog: Synthesis, mRNA translation, and detection

The first example of the synthesis of a new trinucleotide cap analog containing propargyl group such as m^{7,3'-O-propargyl}G(5')PPP(5')A_mpG is reported. The effect of the propargyl group in trinucleotide analog with a standard trinucleotide cap analog (GAG), m⁷G(5')ppp(5')A_mpG was evaluated with respect to their capping efficiency, in vitro T7 RNA polymerase transcription efficiency, and translation activity using cultured A549 lung carcinoma epithelial cells. The new propargyl cap analog is a substrate for T7 RNA polymerase. Notably, the mRNA capped with the propargyl cap is translated ∼ 1.3 times more efficiently than the mRNA capped with the GAG cap. The most characteristic feature of the new propargyl cap analog is that the presence of the propargyl group allows further modification of the mRNA by chemical ligation of an azide-containing fluorescent-labeled substrate to the mRNA via click chemistry.

Solution‐Phase Chemical Synthesis of Modified RNA Dinucleotides

This article describes a simple, reliable, efficient, and improved solution-phase method for the gram-scale chemical synthesis of RNA dinucleotides such as pA_m pA, pA_m pG, and pA_m pU that utilizes phosphoramidite chemistry. The overall synthetic strategy involves three steps. The first step involves the coupling reaction between 5'-O-MMT protected nucleoside-3'-O-phosphoramidite and a protected nucleoside containing a free 5'-OH group in the presence of tetrazole, followed by the oxidation of phosphite triester using tert-butyl hydroperoxide to give the corresponding protected N_m pN. Next, the 5'-O-MMT is cleaved under 3% trichloroacetic acid in dichloromethane conditions. Finally, the 5'-hydroxyl group is phosphorylated by the use of an activated bis(2-cyanoethyl)-N,N-diisopropyl phosphoramidite using tetrazole, followed by the oxidation of trivalent to pentavalent phosphorus using tert-butyl hydroperoxide and subsequent deprotection using ammonium hydroxide to afford the corresponding RNA dinucleotide, pN_m pN, in good yields with high purity (>99.5%). © 2022 Wiley Periodicals LLC.