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.
Thiazolines are a group of isomeric five-membered heterocyclic compounds containing both sulfur and nitrogen. Thiazoline exists in three isomeric forms namely 2-thiazoline, 3-thiazoline and 4-thiazoline. Oxazolines, oxazoles, thiazolines, and thiazoles form the characteristic heterocyclic building blocks of lissoclinum peptide alkaloids.