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2,3,4-Tri-O-benzyl-6-O-trimethylsilyl-α-D-glucopyranosyl bromide reacted with RSHcompounds(R=Et,t-Bu,PhCH_2,p-PhBu~t,Ph,2-benzoxazole,2-benzothiazole),with diisopropyl-ethylamine as base,to give S-D-glucosides.The α-and β-anomeric ratio was dependent on thepKa value of the thiol compound.If pKa value was less than o equal to 7,β-anomer was obtained.If pKa value was equal to or more than 11,α-anomer was obtained.If pKa value was between 9and 10.6,a mixture of α-and β-anomer was obtained.The probable mechanism was discussed.The chemical shifts of proton and carbon in these S-D-glucosides were measured and verified by2D NMR(cosy and hetcor).
2,3,4-Tri-O-benzyl-6-O-trimethylsilyl-α-D-glucopyranosyl bromide reacted with RSHcompounds (R = Et, t- Bu, PhCH 2, p- PhBu ~ t, Ph, 2-benzothiazole) with diisopropyl-ethylamine as base, to give SD-glucosides. Α-and β-anomeric ratio was dependent on the pKa value of the thiol compound. If pKa value was less than o equal to 7, β-anomer was obtained. The pka value was equal to or more than 11, the alpha-anomer was obtained. The pka value was between 9 and 10.6, a mixture of α-and β-anomer was obtained. The probable mechanism was discussed. Chemical shifts of proton and carbon in these SD-glucosides were measured and verified by 2D NMR (cosy and hetcor).