Stereoselective Chemoenzymatic Synthesis of UDP-1,2-cis-furanoses from α,β-Furanosyl 1-Phosphates

The biosynthesis of furanosyl-containing glycoconjugates is poorly described, mainly due to the lack of UDP-furanoses. Here we present our effort to synthesize rare nucleoticle-sugars with the aid of a multiple-enzyme system, notably including galactose-1-phosphate uridylyltransferase. Firstly, STD-NMR techniques were used to probe the broad substrate specificity of this particular enzyme. The chemical synthesis of the needed furanosyl 1-phosphate starting materials was then performed with unprotected thioimidoyl donors. This led to the first stereoselective chemoenzymatic syntheses of UDP-beta-L-arabinofuranose, UDP-alpha-D-fucofuranose and UDP-alpha-D-6F-galactofuranose from starting mixtures of sugar-phosphates. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)