1. FURAN The least aromatic 5-membered ring Reaction with electrophiles - Protonation Conc. H 2 SO 4 Lewis acids (i.e. AlCl 3 ) Decomp.

2. Reaction with electrophiles - Nitration Cannot use conc. HNO 3 / H 2 SO 4 Halogenation

3. Reaction with electrophiles - Acylation Alkylation Generally not practical (polyalkylation, polymerisation) Condensation with Aldehydes and Ketones C.f.

4. Reaction with electrophiles - Condensation with imines / iminium ions Reaction with oxidating agents Reaction with nucleophiles Some ex. on furans activated with -NO 2 group

5. Metallation and further react.

6. Pd-cat couplings c.f. Heteroaryl-Heck

7. Cycloadditions Furanes as diene - one of the first DA examples Furan reacts with many dienophiles (alkenes, alkynes, allenes) exo isolated (termodyn favoured) endo (kinetic prod.) With 1 O 2 Furan as dienophile (only intramolec. ex) Photochemical cycloaddition

8. Furyl-CH 2 -X Oxyfurans Isol. marine sponges cytotoxic Aminofurans -Aminoform -Unstable

9. Synthesis of Furans Strategy a 1 Paal Knorr (1,4-dikacarbonyl) Strategy a - pyrroles Paal Knorr Carbonyl condensations

10. Strategy b

11. Pd-cat. Cyclisations etc.

12. Cycloadditions