1. Heterocyclic Rings Thiophene

2. Importance
Pyrantal 49, is a broad spectrum anthelmintic agent (طارد للديدان المعوية) effective against pinworm and hookworm
Bioten50 (Vitamin H),, occurs in yeast and egg
Thiophene also occurs in organic conducting polymers

3. Ring Synthesis The Pall Synthesis
Lawesson's reagent can be used also in this synthesis.

4. Applications of Lawesson’s reagent

5. The Hinzberg Synthesis

6. The Gewald Synthesis

7. Reactions of Thiophene
Electrophilic Substitution Substitution takes place at the 2- position 
Reactivity pyrrole >> furan > thiophene > benzene
Thiophene tends to undergo substitution rather than addition reactions and it is not so readily cleaved by acids as is furan.

8. Substitution of 2-substituted thiophene

10. Nucleophilic Substitution

11. Cycloaddition Reaction Thiophene is a poor diene

12. Diels-Alder Cycloaddition

13. Cycloadditions of thiophene