Synthesis of 2-deoxy-3,5-di-O-benzoyl-2,2-difluoro-D-ribose from D-glucose and D-mannose. A formal synthesis of gemcitabine

Article abstract of DOI:10.1016/S0040-4020(98)00086-6

The title compound 2-Deoxy-3,5-di-O-benzoyl-2,2-difluoro-D-ribose (17), was synthesised from D-glucose and from D-mannose. The key steps of the synthesis from D-glucose are obtaining the 3,3-difluoropyranose 9 by reacting the ulose 7 with DAST, and their conversion into the difluorofuranoside 17 by a degradative reaction of diol 16. Starting from D-mannose the synthesis obtains the 3,3-difluoroglycal 22 by reaction of the ulose 18 with DAST and oxidation-elimination of selenoglycoside 21. Ozonolysis of 22 gives the difluorofuranose 17.