Synthesis of ‘Iso or Reversed’ C-nucleosides Analogues using Push-pull Activated Monosaccharide Derivatives as Precursors Starting from D-furanose

Iso or Reversed-C-nucleosides constitute a class of nucleoside analogues in which the nucleobase is linked by a carbon-carbon bond to a ribose carbon other than C-1. It is anticipated that iso-C-nucleosides may have increased chemical and enzymatic stability under physiological conditions. In this paper we describe the synthesis of  ethyl 6- (R,S)-7- (E,Z)-3-O-Benzyl-6,8- dicyano-6-deoxy-1,2-O-isopropylidene-7-methylsulfanyl-a-D-xylo-non-7-en-5-ulofuranuronate (11) as sodium salt and 3-O-Benzyl-1,2-O-isopropylidene-5-methylsulfanyl-a-D-xylo-pentofuran- os-5-ulose (15) from 3-O-Benzyl-6-deoxy-1,2-O-isopropylidene-a-D-xylo-hept-5-ulofuranurononitrile (6) synthesis of 6-Aminomethylene-3-O-Benzyl-6-deoxy-1,2-O-isopropylidene-a-D-xylo-hept-5-ulofu-ranurononitrile (21) and 7-Amino-ethyl-6- (3-desoxy-1,2-O-isopropylidene-a-D-glycero-pent-3-eno-furan- uronoyl)-2-methylsulfanyl-pyrazolo[1,5-a]pyrimidine-3-carboxylate (23) from (E)-3-O-Benzyl-6-deoxy-6-dimethylaminomethylene-1,2-O-isopropylidene-a-D-xylo-hept-5-ulofuranurono-nitrile (7) and synthesis of  3-Amino-4- (3-O-Benzyl-1,2-O-isopropylidene-a-D-xylopentofura-nuronoyl)-5-methylsulfanyl-1-H-pyrazole-1-carbamidine (22) from 3-O-Benzyl-6-deoxy-1,2-O-isopropylidene-6-[bis- (methylthio) ethylene]-a-D-xylo-hept-5-ulofuranonitrile (9).

FIRDOUS IMRAN ALI ,IMRAN ALI HASHMI ,HOLGER FIEST ,MANFERED MICHALIK ,KLAUS PESEKE ,