New Chiral Nitrones in the Synthesis of Modified Nucleosides
作者:Róbert Fischer、Alexandra Drucková、Lubor Fiera、Alfonz Rybár、Christian Hametner、MichaŠ K. Cyrański
DOI:10.1055/s-2002-32579
日期:——
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 the Z-configuration of the nitrone through exo and endo transition states from the si face of nitrone (C-1'/C-3 erythro) affords C-3/C-5 cis