1999 nucleic acids

nucleic acidsU 0700

06 - 203Synthesis of Novel Bicyclo[2.2.1] Ribonucleosides: 2’-Amino- and2’-Thio-LNA Monomeric Nucleosides. — The formation of benzylatednucleosides (X) and (XII) is readily achieved by treatment of tosylates (III)with either benzylamine or potassium thioacetate.The thymidine derivative (X)is successfully debenzylated to afford the desired deprotected nucleoside (XI),whereas the direct debenzylation of the uridine derivative (XII) fails, probablydue to catalyst poisoning. The deprotection of the tricyclic intermediate (VII),derived from nucleoside (IIIa), is thus the route of choice to obtain derivative(VIII). — (SINGH, S. K.; KUMAR, R.; WENGEL, J.; J. Org. Chem. 63(1998) 18, 6078-6079; Dep. Chem., H. C. Oersted Inst., Univ. Copenhagen,DK-2100 Copenhagen, Den.; EN)

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