Synthesis of 6‑Alkyluridines from 6‑Cyanouridine via Zinc(II) Chloride-Catalyzed Nucleophilic Substitution with Alkyl Grignard Reagents

6-Cyanouracil
derivatives underwent a direct nucleophilic substitution
reaction with alkyl Grignard reagents in the presence of zinc­(II)
chloride as a catalyst to form the corresponding 6-alkyluracils. This
methodology is applicable to sugar-protected 6-cyanouridine and 6-cyano-2′-deoxyuridine
without the protection at the N3-imide
and provides a facile and general access to versatile 6-alkyluracil
and 6-alkyluridine derivatives.