Q51E - Organic Chemistry (Mcmurry)

Question

Primary amines react with esters to yield amides: RCO₂R^' + R^"NH₂ $\to$RCONHR^" + R^'OH  . Propose a mechanism for the following reaction of an a b-unsaturated ester.

Step-by-Step Solution

Answer

Step 1: Reaction of primary amine and ester to give amide

When ester reacts with primary amine or ammonia in an acidic medium then they give amide as a product.

In this reaction, the first step includes a nucleophilic attack of nitrogen on the carbonyl center followed by proton transfer and the alcohol portion of ester is lost.

Step 2: Mechanism of the given reaction

In the given reaction first, the lone pair of nitrogen attack the double-bonded carbon and further rearrangements take place as shown below;

In the next step, intramolecular rearrangements take place. Lone pair of nitrogen attacks the carbonyl carbon and we get the desired product.