Identify compounds A and E in the following reaction sequence.

Formation of Compound A

Formation of Compound B (Reduction)

• Reagent: $$\text{Sn} / \text{HCl}$$
• Transformation: This is a selective reduction reaction that converts the nitro group ($$-\text{NO}_2$$) into a primary amine group ($$-\text{NH}_2$$).
• Compound B: 3-bromo-4-ethylaniline.

Step 3: Formation of Compound C (Diazotization)

• Reagent: $$\text{NaNO}_2 / \text{HCl}$$ at $$273\text{--}278\text{ K}$$ ($$0\text{--}5^\circ\text{C}$$).
• Transformation: The primary aromatic amine group ($$-\text{NH}_2$$) reacts to form a stable aromatic diazonium salt ($$-\text{N}_2^+\text{Cl}^-$$).
• Compound C: 3-bromo-4-ethylbenzenediazonium chloride.

Formation of Compound D (Deamination)

• Reagent: $$\text{C}_2\text{H}_5\text{OH}$$ (Ethanol) or $$\text{H}_3\text{PO}_2$$.
• Transformation: Ethanol acts as a mild reducing agent that replaces the diazonium group ($$-\text{N}_2^+\text{Cl}^-$$) with a hydrogen atom ($$-\text{H}$$), effectively removing it from the ring.
• Compound D: 1-bromo-2-ethylbenzene (o-bromoethylbenzene).

Formation of Compound E (Side-chain Oxidation)

• Reagent: (i) $$\text{KMnO}_4 / \text{KOH}$$, (ii) $$\text{H}_3\text{O}^+$$
• Transformation: Potassium permanganate under basic heating conditions oxidizes any alkyl side chain containing benzylic hydrogens completely down to a carboxylic acid group ($$-\text{COOH}$$). Acid workup ($$\text{H}_3\text{O}^+$$) protonates the resulting carboxylate salt.
• Compound E: 2-bromobenzoic acid.

Option B