Regioselective Synthesis of 5-Substituted 3-(β-d-Glycopyranosyl)isoxazoles and -isoxazolines by 1,3-Dipolar Cycloaddition as Potential Anticancer Agents and Glycogen Phosphorylase Inhibitors

Anhydro-aldose oximes were employed to generate in situ nitrile oxides via a halogenation/base-induced elimination sequence in the presence of NCS and Et(3)N, which were then used in 1,3-dipolar cycloadditions with alkenes and alkynes to afford 5-substituted 3-(β-d-glycopyranosyl)isoxazole and -isoxazoline derivatives exclusively. These newly synthesized glycomimetics were evaluated for their potential to act as antagonists of A2780 ovarian cancer cells and as inhibitors of glycogen phosphorylase; however, they exhibited no significant activity.