New Chiral Nitrones in the Synthesis of Modified Nucleosides

• DOI: 10.1055/s-2002-32579
• Publication Date: 2002-07-28T21:53:25Z
• Authors: Róbert Fischer; Alexandra Drucková; Lubor Fiera; Alfonz Rybár; Christian Hametner; MichaŠ K. Cyrański
• Keywords: Nitrone; Diastereomer; Uracil

New chiral nitrones 7 and 12, easily prepared from d-xylose by multistep synthetic routes, undergo regioselective 1,3-dipolar cycloadditions with N-vinylated bases (uracil, adenine) giving isoxazolidinyl nucleosides in good yields. Attack of the dipolarophile on Z-configuration nitrone through exo endo transition states si face (C-1′/C-3 erythro) affords C-3/C-5 cis (exo) trans (endo) isoxazolidines as two major isomers.