Benzofuran is the heterocyclic compound consisting of fused benzene and furan rings. This colourless liquid is a component of coal tar. Benzofuran is the structural nucleus (parent compound) of many related compounds with more complex structures. For example, psoralen is a benzofuran derivative that occurs in several plants.

There are benzofuran based herbicides: ethofumesate and benfuresate. Several psychoactive drugs such as 5-MAPB and 6-APB are also derived from benzofuran.

Production

Benzofuran is extracted from coal tar. It is also obtained by dehydrogenation of 2-ethylphenol.

Laboratory methods

Benzofurans can be prepared by various methods in the laboratory. Notable examples include:

• O-alkylation of salicylaldehyde with chloroacetic acid followed by dehydration (cyclication) of the resulting ether and decarboxylation.

  Perkin rearrangement, where a coumarin is reacted with a hydroxide:

  Diels–Alder reaction of nitro vinyl furans with various dienophiles:

  Cycloisomerization of alkyne ortho-substituted phenols:

Related compounds

• Substituted benzofurans

• Dibenzofuran, an analog with a second fused benzene ring.

• Furan, an analog without the fused benzene ring.

• Indole, an analog with a nitrogen instead of the oxygen atom.

• Benzothiophene, an analog with a sulfur instead of the oxygen atom.

• Isobenzofuran, the isomer with oxygen in the adjacent position.

• Aurone

• Thunberginol F

References