Postsynthetic On-Column 2′ Functionalization of RNA by Convenient Versatile Method

Abstract

We report a universal straightforward strategy for the chemical synthesis of modified oligoribonucleotides containing functional groups of different structures at the 2’ position of ribose. The on-column synthetic concept is based on the incorporation of two types of commercial nucleotide phosphoramidites containing orthogonal 2’-O-protecting groups, namely 2’-O-thiomorpholine-carbothioate (TC, as “permanent”) and 2’-O-tert-butyl(dimethyl)silyl (tBDMS, as “temporary”), to RNA during solid-phase synthesis. Subsequently, the support-bound RNA undergoes selective deprotection and follows postsynthetic 2’ functionalization of the naked hydroxyl group. This convenient method to tailor RNA, utilizing the advantages of solid phase approaches, gives an opportunity to introduce site-specifically a wide range of linkers and functional groups. By this strategy, a series of RNAs containing diverse 2’ functionalities were synthesized and studied with respect to their physicochemical properties.

Amine‐to‐Azide Conversion on Native RNA via Metal‐Free Diazotransfer Opens New Avenues for RNA Manipulations

“…RNA containing such modifications is endowed with functional groups that are distinct from the repetitive nucleotide pattern of RNA, and therefore, they can serve as handle for specific and selective transformations. Reactive handles can also be generated through metabolic labeling of RNA [14–21] or by RNA solid‐phase synthesis [22–30] …”

“…Reactive handles can also be generated through metabolic labeling of RNA [14][15][16][17][18][19][20][21] or by RNA solidphase synthesis. [22][23][24][25][26][27][28][29][30] In the present work, we have searched for a solution to convert an RNA containing a primary amino group into the corresponding azide-modified RNA, leaving the nucleobase amines unaffected (Figure 1). Finding such a conversion reaction would open new avenues for RNA labeling, for the preparation of RNA-peptide conjugates, and for the selective isolation and identification of cellular RNAs with nucleotide modifications, such as 3-(3-amino-3-carboxypropyl)uridine (acp 3 U), [31] lysidine (k 2 C), [32] 5-aminomethyl-2-thiouridine (mn 5 s 2 U), [9] and many others (Supporting Figure S1).…”

“…Reactive handles can also be generated through metabolic labeling of RNA[ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 ] or by RNA solid‐phase synthesis. [ 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 ]…”