LNA 5′-phosphoramidites for 5′→3′-oligonucleotide synthesis

Abstract

Hereby we report an efficient synthesis of LNA thymine and LNA 5-methylcytosine 5′-phosphoramidites, allowing incorporation of LNA thymine and LNA 5-methylcytosine into oligonucleotides synthesized in the 5′→3′ direction. Key steps include regioselective enzymatic benzoylation of the 5′-hydroxy group of unprotected LNA thymine, and subsequent 4,4′-dimethoxytritylation of the 3′-hydroxy group of the O5′-benzoylated LNA thymine nucleoside.