A carbonyl compound P, which gives positive iodoform test, undergoes reaction with MeMgBr followed by dehydration to give an olefin Q. Ozonolysis of Q leads to a dicarbonyl compound R, which undergoes intramolecular aldol reaction to give predominantly S.
The structure of the product S is
(A)(see structure)
(B)(see structure)✓ Correct
(C)(see structure)
(D)(see structure)
Answer: (B)
Solution
The dicarbonyl compound R undergoes intramolecular aldol condensation. In this reaction:
The enolate of one carbonyl attacks the other carbonyl
This forms a cyclic β-hydroxy ketone
Dehydration gives the α,β-unsaturated ketone S
Based on the structure of R and the aldol mechanism, the predominant product S is shown in option (B), which is a bicyclic α,β-unsaturated ketone.
JEE Advanced · 2009 · 12 Apr 2009 · Paper 1 · Single correct option
