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.
Oxazines are heterocyclic compounds containing one oxygen and one nitrogen atom in a diunsaturated six-membered ring. The existence of isomers depends on the relative positions of the heteroatoms and the relative positions of the double bonds.
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