Question

The correct sequence of reactions for the synthesis of the following molecule is(are) 

• A. (i) 4-Iodophenol, Mg, ether
  (ii) Cyclopropane carboxaldehyde, THF
  (iii) CsCO₃, MeI, THF
• B. (i) Cyclopropyl bromide, Mg, ether
  (ii) 4-Hydroxybenzaldehyde, THF
  (iii) CsCO₃, MeI, THF
• C. (i) 4-Iodophenol, CsCO₃, MeI, THF
  (ii) Mg, ether
  (iii) Cyclopropane carboxaldehyde, THF
• D. (i) Cyclopropyl bromide, Mg, ether
  (ii) Methyl 4-methoxybenzoate, THF

Hint:

In synthesis, carefully follow the reagent order and conditions to ensure proper functional group transformations.

Answer 1

The Correct Option is C

To synthesize the given molecule, we need to consider the steps in a strategic sequence, ensuring each chemical reaction aligns with desired transformations in the target compound.

The correct sequence of reactions is as follows:

1. Step 1: Methylation of 4-Iodophenol 
   Starting with 4-Iodophenol, we use cesium carbonate (CsCO₃) and methyl iodide (MeI) in tetrahydrofuran (THF) to introduce a methoxy group at the para position. This produces 4-Methoxy-phenol. 
   \(\text{4-Iodophenol} \xrightarrow{\text{CsCO}_3/\text{MeI}} \text{4-Methoxyphenol}\)
2. Step 2: Formation of Grignard Reagent 
   Next, we convert 4-Methoxyphenol into a Grignard reagent using magnesium (Mg) in ether. This step prepares the molecule to react with an aldehyde. 
   \(\text{4-Methoxyphenol} \xrightarrow{\text{Mg/ether}} \text{Grignard Reagent}\)
3. Step 3: Addition to Cyclopropane Carboxaldehyde 
   The Grignard reagent then reacts with cyclopropane carboxaldehyde in THF. The addition of the Grignard reagent to the aldehyde forms a secondary alcohol, specifically attaching the cyclopropane ring to the aromatic structure. 
   \(\text{Grignard Reagent} + \text{Cyclopropane Carboxaldehyde} \rightarrow \text{Target Molecule}\)

The sequence in the correct option ensures all functional groups are introduced and manipulated in a logical manner that aligns with standard organic synthesis techniques.

Correct Answer: Option 3

(i) 4-Iodophenol, CsCO₃, MeI, THF 
(ii) Mg, ether 
(iii) Cyclopropane carboxaldehyde, THF

By following these steps, we efficiently synthesize the target molecule with the desired arrangement of functional groups.