Question

The intermediate shown here is formed during the hydroxide-ion-promoted hydrolysis of ester group. Propose a mechanism for the reaction.

Short answer

When hydroxide ion attacks the N-H bond, electron delocalization occurs and water molecule is removed. Cyclisation also occurs.

Attack of hydroxide ion

Step-by-step solution

Step-by-Step SolutionStep1 : Attack of hydroxide ion 

When hydroxide ion attacks the N-H bond, electron delocalization occurs and water molecule is removed. Cyclisation also occurs.

Attack of hydroxide ion

Step 2: Attack of hydroxyl ion at carbonyl carbon

Hydroxyl ion is attacked at the carbonyl carbon, which release ${\mathrm{CF}}_3{\mathrm{CH}}_2{\mathrm{O}}^{-}$.

Attack of hydroxyl ion at carbonyl carbon

Attack of proton at N - C bond

Proton is attacked at the bond and electron delocalization occurs and the ring is opened.

Attack of proton at bond

Chirality of 3-methylpentan- 2,3- diol

Lastly, the water molecules are released by forming—a carboxylate anion.

Chirality of 3-methylpentan- 2,3- diol