A Facile and Improved Synthesis of 3-Fluorothiophene

A new efficient and convenient route to 3-fluoro­thiophene in four steps and 49% overall yield is reported. The fluorine atom was successfully introduced into the thiophene ring in 67% yield using the Schiemann reaction on 2-methoxycarbonyl­thiophene-3-diazonium tetrafluoroborate. The product, methyl 3-fluorothiophene-2-carboxylate was saponified and the 3-fluorothiophene-2-carboxylic acid was decarboxylated to afford 3-fluorothiophene in 93% yield.