Pyrimidine, also known as 1,3-diazobenzene, is a heterocyclic compound with the chemical formula C4H4N2. Pyrimidine is formed by substituting 2 nitrogen atoms for 2 carbons in the meta-position of benzene. It is a diazine and retains its aromaticity. Derivatives of pyrimidine widely exist in organic macromolecular nucleic acids, and many drugs also contain pyrimidine rings. In nucleic acids, three nucleobases are pyrimidine derivatives: cytosine, thymine and uracil. There are a variety of pyrimidine-containing drugs on the market, most of which are kinase inhibitors.
Tetrahydrothiophene is a sulfur-containing saturated heterocyclic compound obtained by catalytic hydrogenation of thiophene. After thiophene is reduced to tetrahydrothiophene, it no longer has a conjugated system and aromaticity. Therefore, tetrahydrothiophene shows the properties of general thioethers. Easily oxidized to sulfoxides and sulfones. Tetrahydrothiophene can be used as a raw material for the production of pharmaceuticals, pesticides and photochemicals.