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.
Triazines are an important class of six-membered aromatic heterocycles with three nitrogen atoms that give rise to three regioisomers: 1,2,4-triazines, 1,2,3-triazines, and 1,3, 5-triazine. 1,2,3-Triazines show remarkable reactivity and have attracted attention for their medicinal value. Triazine compounds fused with other carbon and heterocycles are stable and have a broad spectrum of pharmacological activities.