Thiophene-2-carboxaldehyde is an organosulfur compound with the formula C4H3SCHO.

It is a colorless liquid that often appears amber after storage.

It is versatile precursor to many drugs including eprosartan, Azosemide, and Teniposide.

It can be prepared from thiophene by the Vilsmeier reaction.

[1] Alternatively, it is prepared from chloromethylation of thiophene.