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[摘要]：The copper-catalyzed azide alkyne cycloaddition (CuAAC) is a highly effective method for the selective incorporation of deuterium atom into the C-5 position of the 1,2,3-triazole structure. Reactions of alkynes and azides can be conveniently carried out in a biphasic medium of CH2Cl2/D2O, using the CuSO4/Na ascorbate system. The mildness of the method renders it applicable to substrates of relatively high complexity, such as nucleosides. Good yields and high levels of deuterium incorporation were observed. A reaction conducted in equimolar H2O and D2O showed 2.7 times greater incorporation of hydrogen atom as compared to deuterium. This is consistent with the H+ and D+ ion concentrations in H2O and D2O, respectively. With appropriately deuterated precursors, partially to fully deuterated triazoles were assembled where the final deuterium atom was incorporated in the triazole-forming step. |
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