Question

Draw a stepwise mechanism for each reaction.

Short answer

a

b

Step-by-step solution

Pyrrolidine

Pyrrolidine is a cyclic saturated N-containing organic compound that is classified as a secondary amine.

The given pyrrolidines can be synthesized by the given mechanism.

Mechanism

a.The lone pair of electrons would attack the electrophilic carbon as the bromide ion leaves the molecule.

Deprotonation of the molecule occurs in the presence of the strong base sodium hydroxide.

The lone pair of electrons would attack the carbon for ring closure, followed by deprotonation to form the required pyrrolidine.

Formation of pyrrolidine

b

The lone pair of electrons on the nitrogen atom would attack the carbonyl carbon to form the cyclic ion.

The abstraction of a proton follows the intramolecular proton transfer by the oxygen atom.

Dehydration followed by a shift of electrons would give the required pyrrolidine.

Formation of cyclic amine