Access to 1'-Amino Carbocyclic Phosphoramidite to Enable Postsynthetic Functionalization of Oligonucleotides.

We report a synthesis of a carbocyclic, abasic RNA phosphoramidite decorated with an amino functionality. The building block was efficiently incorporated into an RNA oligonucleotide in a site-specific manner, followed by deprotection to a free amino group. The amino moiety could be further derivatized as exemplified with fluorescein N-hydroxysuccinimide ester. Hence, this convertible building block may provide access to a variety of RNA oligonucleotides via postsynthetic amino group functionalization. In particular, providing a vector toward nucleobase replacements.