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

Abstract

Abstract. The preparation and high-resolution 'H NMR conformational analysis of the two novel nucleoside analogues, 1-(3'-C-methyl-2'-deoxy-~-~-xylofuranosyl)urac~l (compound 1) and 9-(3'-C--methyl-2'-deoxy-f3-~-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 y' (trans orientation of 0 5 ' 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 P-face of the furanosyl moiety) is revised on the basis of these data.