Synthesis and conformation of 1‐(3′‐<i>C</i>‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)uracil and 9‐(3′‐<i>C</i>‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)adenine; two novel sugar‐methylated nucleoside analogues

Abstract

Abstract The preparation and high‐resolution 1 H NMR conformational analysis of the two novel nucleoside analogues, 1‐(3′‐ C ‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)uracil (compound 1 ) and 9‐(3′‐ C ‐methyl‐2′‐deoxy‐β‐D‐xylofuranosyl)adenine (compound 2 ), are described. Compounds 1 and 2 show a pronounced preference for the north conformation of the sugar ring. The north conformation corresponds with a sterically favoured equatorial location of the methyl group. The C4′ ‐ C5′ conformation in 1 and 2 is predominantly γ t ( trans orientation of O5′ and C3′). The configuration at C3′ in 1 and 2 was corroborated via a one‐dimensional NOE experiment. The structure of compound 1 (originally assigned as having the C3′‐methyl group on the β‐face of the furanosyl moiety) is revised on the basis of these data.