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.