Herein we report the synthesis, conformational analysis and the evaluation of the antiviral activity of six-membered nucleoside analogues having a piperidine ring as the preorganized (deoxy)ribose bioisostere. Mutagenic nucleobase-containing nucleosides 1 and 2 were obtained by appropriate manipulation of the well-known glycomimetic agent deoxynojirimycin as easily accessible starting material. In vitro assays revealed activity of 5-iododeoxyuridine analogue 1 against all DNA viruses tested. As suggested by DFT analysis and pH-dependent NMR experiments, antiviral activity was correlated to the biomimetic character of the piperidine ring, as it is able to resemble the deoxyribose conformations adopted by natural nucleosides when interacting with viral enzymes.