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.

中文翻译：

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3-氟噻吩的简便和改进合成

报道了一种新的高效便捷的四步制备 3-氟噻吩路线，总产率为 49%。使用 2-甲氧基羰基噻吩-3-重氮四氟硼酸盐的 Schiemann 反应成功地将氟原子引入噻吩环，产率为 67%。产物3-氟噻吩-2-羧酸甲酯被皂化，3-氟噻吩-2-羧酸脱羧，得到3-氟噻吩，产率为93%。