293751-10-7Relevant articles and documents
IMPROVED SYNTHESIS OF ?2.2.1|BICYCLO NUCLEOSIDES
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Page/Page column 13; 35, (2008/06/13)
A synthesis of [2.2.1]bicyclo nucleosides which is shorter and provides higher overall yields proceeds via the key intermediate of the general formula III, wherein R4 and R5 are, for instance, sulfonates and R7 is, for instance, a halogen or an acetate. F
A simplified and efficient route to 2′-O, 4′-C-methylene-linked bicyclic ribonucleosides (locked nucleic acid)
Koshkin,Fensholdt,Pfundheller,Lomholt
, p. 8504 - 8512 (2007/10/03)
A novel efficient method for the synthesis of locked nucleic acid (LNA) monomers is described. The LNA 5′,3′-diols containing thymine, 4-N-acetyl- and 4-N-benzoylcytosine, 6-N-benzoyladenine, and 2-N-isobutyrylguanine as nucleobases were prepared via convergent syntheses. The method is based on the use of the common sugar intermediate 1,2-di-O-acetyl-3-O-benzyl-4-C-methanesulfonoxymethyl- 5-O-methanesulfonyl-D-erythro-pentofuranose (8) that easily can be prepared from D-glucose in multigram scale. Four different nucleobases were stereoselectively coupled to 8 using a modified Vorbrueggen procedure to give the corresponding 4′-C-branched nucleoside derivatives. Subsequent ring closing furnished the protected LNA nucleosides. The 5′-O-mesyl groups were efficiently displaced by nucleophilic substitution using sodium benzoate. Saponification of the 5′-benzoates followed by catalytic removal of the 3′-O-benzyl groups afforded the free LNA diols. The exocyclic amino groups of adenosine and cytidine were selectively acylated to give 4-N-acetyl- or 4-N-benzoyl-LNA-C and 6-N-benzoyl-LNA-A. The isobutyryl group of guanine was retained during the preparation of 2-N-isobutyryl-LNA-G. The LNA-T diol and base-protected LNA diols can be directly converted into LNA-phosphoramidites for automated chemical synthesis of LNA containing oligonucleotides.