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.
The pyrazolopyrazine ring system is a very interesting class of heterocyclic compounds considered as important scaffolds for many effective bioactive agents with low toxicity, antioxidant, anticonvulsant, antiparasitic, anti-inflammatory, antiviral, antibacterial, anti- Fungal and analgesic activity.