SYNTHESIS OF 3-AMINO-2,3,6-TRIDEOXY-D-ribo- AND -L-lyxo-HEXOFURANOSES SUITABLE FOR NUCLEOSIDE SYNTHESIS

Article abstract of DOI:10.1016/S0008-6215(00)81904-7

N-Acetylepidaunosamine (3-acetamido-2,3,6-trideoxy-D-ribo-hexopyranose) was converted into the diethyl dithioacetal and this was cyclized with HgCl2, HgO, and MeOH, to give methyl 3-acetamido-2,3,6-trideoxy-α- and -β-D-ribo-hexofuranoside (4 and 5).These anomers were acetylated or (p-nitrobenzoyl)ated, and the esters were subjected to acetolysis, to afford 3-acetamido-1,5-di-O-acetyl-2,3,6-trideoxy-D-ribo-hexofuranose and 3-acetamido-1-O-acetyl-2,3,6-trideoxy-5-O-(p-nitrobenzoyl)-D-ribo-hexofuranose, respectively.Alternatively, compounds 4 and 5 were hydrolyzed to the free bases with barium hydroxide, and these were converted into the trifluoroacetamido derivatives which, on (p-nitrobenzoyl)ation and acetolysis, afforded 1-O-acetyl-2,3,6-trideoxy-5-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-D-ribo-hexofuranose.To prepare the corresponding daunosamine derivative, 2,3,6-trideoxy-3-(trifluoroacetamido)-L-lyxo-hexopyranose was converted into the diethyl dithioacetal, and this was cyclized in the same way, to afford methyl 2,3,6-trideoxy-3-(trifluoroacetamido)-α- and -β-L-lyxo-hexofuranoside.On (p-nitrobenzoyl)ation and acetolysis, both afforded 1-O-acetyl-2,3,6-trideoxy-5-O-(p-nitrobenzoyl)-3-(trifluoroacetamido)-L-lyxo-hexofuranose.