Thiophene is a five-membered heterocyclic compound containing a sulfur heteroatom with the molecular formula C4H4S. Thiophene is aromatic and is very similar to benzene; electrophilic substitution reaction is easier than benzene, and it is mainly substituted at the 2-position. Thiophene ring system has certain stability to oxidant.
Thienopyrimidines are a class of heterocyclic compounds with diverse biological activities depending on their detailed substitution patterns. In addition, many thienopyrimidine derivatives have shown potent activity against cancer cell lines and specific oncogenes.