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.
Thiadiazoles are a subfamily of azoles. Structurally, they are five-membered heterocyclic compounds containing two nitrogen atoms and one sulfur atom, and two double bonds, forming an aromatic ring. Depending on the relative positions of the heteroatoms, there are four possible structures; these forms do not interconvert and are therefore structural isomers rather than tautomers. These compounds themselves are rarely synthesized and have no particular utility, however, compounds that use them as structural motifs are fairly common in pharmacology.