Norbornane as the novel pseudoglycone moiety in nucleosides

Novel nucleoside analogues based on bicyclo[2.2.1]heptene/heptane were prepared by linear synthesis starting from commercially available 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene 1. The crucial step of the synthesis was insertion of the amino group to the position 7 of the substituted bicyclo[2.2.1]heptene with anti-configuration by a Ritter reaction (H₂SO₄, AcOH, CH₃CN). All nucleobases were constructed at this amino function. The prepared family of the target nucleosides was tested for cytostatic and antiviral activity.