Stereoselective synthesis of 2-deoxy-2-fluoroarabinofuranosyl-alpha-1-phosphate and its application to the synthesis of 2'-deoxy-2'-fluoroarabinofuranosyl purine nucleosides by a chemo-enzymatic method.

Stereoselective introduction of a phosphate moiety into 2-deoxy-2-fluoroarabinofuranose derivatives at the anomeric position was investigated by two methods. One involved a stereoselective hydrolysis of 1-bromo-derivative, and the consecutive phosphorylation of 2-deoxy-2-fluoro-alpha-D-arabinofuranose via a phosphoramidite derivative. The other method involved stereoselective alpha-phosphorylation of the 1-bromo-derivative at the 1-position. The resulting alpha-1-phosphate was utilized to prepare 2'-deoxy-2'-fluoroarabinofuranosyl purine nucleosides by an enzymatic glycosylation reaction. This chemo-enzymatic method will be applicable to the synthesis of some 2'F-araNs, and three important 2'F-araNs were actually obtained in 30-40% yields from 1,3,5-tri-O-benzoyl-2-deoxy-2-fluoro-alpha-D-arabinose with high purity.