Cyano Sugars: Synthesis by Opening of an Epoxide Ring in Pentofuranosides with Diethylaluminum Cyanide

Abstract

Abstract Reaction of diethylaluminum cyanide (DEAC) with methyl 2,3-anhydroribo-furanosides was examined as a potentially useful method for the introduction of the cyano group at C-2 and C-3 of furanosyl sugars. Thus, treatment of methyl 2,3-anhydro-5-O-benzyl-β-D-ribofuranoside with DEAC provided methyl 5-O-benzyl-3-cyano-3-deoxy-β-D-xylyofuranoside (2), while similar treatment of methyl 2,3-anhydro-5-O-benzyl-α-D-ribofuranoside gave a mixture of methyl 5-O-benzyl-3-cyano-3-deoxy-α-D-xylofuranoside (5) and methyl 5-O-benzyl-2-cyano-2-deoxy-α-D-arabinofuranoside (6). Epimerization of 2 at C-3 was readily effected in the presence of base to give methyl 5-O-benzyl-3-cyano-3-deoxy-β-D-ribofuranoside (9). In contrast, 5 and 6 were resistant to base-promoted epimerization. Sequential acetylation and acetolysis converted the cyano sugars 2 and 9 into the corresponding tri-O-acetyl derivatives 13, 14 and 15.