An improved synthesis of 5-fluoro-2′-deoxyuridine incorporating isotopic labels

The title compound has been synthesized by a new route that requires less steps and gives higher overall yields than existing procedures. The synthesis makes use of low molecular weight starting materials that are commercially available in isotopically enriched forms and thereby enables the specific labelling of carbons in the pyrimidine ring. An improved synthesis of the versatile reagent methyl propiolate is also included.