First Synthesis of a Natural Neopterin Glycoside: 3'-O-(β-D-Glucopyranosyluronic acid)neopterin

1',2'-Di-O-acetyl-N2-(N,N-dimethylaminomethylene)-3-[2-(4-nitrophenyl)ethyl]neopterin (1) was prepared from neopterin in 5 steps. Glycosylation of 1 with methyl 2,3,4-tri-O-benzoyl-α-D-glucopyranosyluronate bromide in the presence of silver triflate and tetramethylurea afforded the corresponding 3'-O-(methyl β-D-glucopyranosyluronate) neopterin derivative (2) in 64% yield. The first synthesis of 3'-O-(β-D-glucopyranosyluronic acid)neopterin was achieved by successive removal (4 steps) of the protecting groups of 2.