Question

The major products P and Q of the following reactions are 

Hint:

The reaction sequence involves the formation of an enolate using a strong base (LDA) followed by nucleophilic substitution with an alkyl halide (phenyl bromide).

Answer 1

Step 1: Understanding the reaction conditions.
The first reaction involves lithium diisopropylamide (LDA) at a low temperature (\( -78^\circ C \)), which is a strong base used for deprotonation. It will deprotonate the alpha-carbon (next to the carbonyl) to form an enolate ion, which is a good nucleophile. This is a typical reaction in the aldol or related enolate chemistry.
Step 2: Analyzing the products.
The second reaction involves sodium hydride (NaH), a strong base, and phenyl bromide. The enolate formed in the first step will attack the phenyl group via an SN2 mechanism, resulting in a substitution product, which is Q.
Step 3: Conclusion.
The correct products P and Q are shown in option (D), where P is the enolate intermediate formed and Q is the final product after the nucleophilic substitution with phenyl bromide.
Final Answer: \[ \boxed{\text{P and Q are as shown in Option (D).}} \]