111(P44) guanofosfocinの合成研究-8-(マンノピラノシルオキシ)アデノシン誘導体の合成(ポスター発表の部)

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Two approaches for the synthesis of 8-(glycosyloxy)purine nucleoside, which is found in a recently isolated chitin synthase inhibitor-guanofosfocin, have been examined. One contains substitution reaction of alcohol with purine nucleoside bearing a leaving group at the 8 position. Through a number of model reactions using cyclohexanol as a nucleophile and 8-substituted adenosine derivatives as a substrate, we finally found that N^6-benzoyl-8-bromoadenosine derivative 1j reacted with sodium alkoxides derived from di-O-isopropylidene-α-D-mannoses, 6 and 7, in DMF at room temperature to yield 8-(mannosyloxy)adenosines 10 and 11 in reasonable yields. Another approach involves glycosylation reaction of 8-oxoadenosine derivatives with appropriate mannosyl donors. We found that N^6-trityl-adenosine derivative 13a was a suitable substrate for this reaction. When tetra-O-benzylmannnosyl bromide 16 was allowed to react with 13a in the presence of silver carbonate in toluene at 60℃, 8-(mannosyloxy)adenosine 15a is obtained in 79% yield. The 8-mannosyloxy products were isolated solely as α anomers, assigned by ^1J_<C-H>, value of C-1 in the mannose moiety.
天然有機化合物討論会の論文
1998-08-31