Question

What will be the product(s) of the following intramolecular Clasien condensation ?

• A. I
• B. II
• C. I and II
• D. II and III

Answer 1

The correct option is D II and III

The given reaction is a intramolecular claisen condensation.

Here, the enolate ion formed at alpha carbon of one ester group will attack the electrophilic carbon of other ester group to form stable cyclic product.
Five membered ring are stable than four membered ring.

Lets give a random numbering to the carbon atoms in the molecule for an easier explanation.
Possible 5 membere cyclic products:
1. Enolate ion formed at carbon (2) can attack the electrophilic carbon (8) to form a five member cyclic product.


2. Enolate ion formed at carbon (7) can attack electrophilic carbon (5)

3. Enolate ion formed at carbon (7) can attack the electrophilic carbon (1)

4. Enolate ion formed at carbon (4) can attack the electrophilic carbon (8)

Thus, only (II) and (III) are formed not (I).
Hence, option (d) is correct.