Which of the following statement is not correct regarding five membered heterocyclic compounds?
1
Furan is least aromatic in nature among furan, thiophene and pyrrole.
2
Thiophene can have more number of canonical structures using 3d-orbitals.
3
Pyrrole has maximum double bond character among furan, thiophene and pyrrole.
4
Furan, thiophene and pyrrole can be synthesized using Paal-Knorr synthesis.